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12<div class="ARTICLE">
13<div class="TITLEPAGE">
14<h1 class="TITLE"><a name="AEN2" id="AEN2">NCURSES Programming
15HOWTO</a></h1>
16<h3 class="AUTHOR"><a name="AEN4" id="AEN4">Pradeep Padala</a></h3>
17<div class="AFFILIATION">
18<div class="ADDRESS">
19<p class="ADDRESS"><code class="EMAIL">&lt;<a href=
20"mailto:ppadala@gmail.com">ppadala@gmail.com</a>&gt;</code></p>
21</div>
22</div>
23<p class="PUBDATE">v1.9, 2005-06-20<br></p>
24<div class="REVHISTORY">
25<table width="100%" border="0">
26<tr>
27<th align="left" valign="top" colspan="3"><b>Revision
28History</b></th>
29</tr>
30<tr>
31<td align="left">Revision 1.9</td>
32<td align="left">2005-06-20</td>
33<td align="left">Revised by: ppadala</td>
34</tr>
35<tr>
36<td align="left" colspan="3">The license has been changed to the
37MIT-style license used by NCURSES. Note that the programs are also
38re-licensed under this.</td>
39</tr>
40<tr>
41<td align="left">Revision 1.8</td>
42<td align="left">2005-06-17</td>
43<td align="left">Revised by: ppadala</td>
44</tr>
45<tr>
46<td align="left" colspan="3">Lots of updates. Added references and
47perl examples. Changes to examples. Many grammatical and stylistic
48changes to the content. Changes to NCURSES history.</td>
49</tr>
50<tr>
51<td align="left">Revision 1.7.1</td>
52<td align="left">2002-06-25</td>
53<td align="left">Revised by: ppadala</td>
54</tr>
55<tr>
56<td align="left" colspan="3">Added a README file for building and
57instructions for building from source.</td>
58</tr>
59<tr>
60<td align="left">Revision 1.7</td>
61<td align="left">2002-06-25</td>
62<td align="left">Revised by: ppadala</td>
63</tr>
64<tr>
65<td align="left" colspan="3">Added "Other formats" section and made
66a lot of fancy changes to the programs. Inlining of programs is
67gone.</td>
68</tr>
69<tr>
70<td align="left">Revision 1.6.1</td>
71<td align="left">2002-02-24</td>
72<td align="left">Revised by: ppadala</td>
73</tr>
74<tr>
75<td align="left" colspan="3">Removed the old Changelog section,
76cleaned the makefiles</td>
77</tr>
78<tr>
79<td align="left">Revision 1.6</td>
80<td align="left">2002-02-16</td>
81<td align="left">Revised by: ppadala</td>
82</tr>
83<tr>
84<td align="left" colspan="3">Corrected a lot of spelling mistakes,
85added ACS variables section</td>
86</tr>
87<tr>
88<td align="left">Revision 1.5</td>
89<td align="left">2002-01-05</td>
90<td align="left">Revised by: ppadala</td>
91</tr>
92<tr>
93<td align="left" colspan="3">Changed structure to present proper
94TOC</td>
95</tr>
96<tr>
97<td align="left">Revision 1.3.1</td>
98<td align="left">2001-07-26</td>
99<td align="left">Revised by: ppadala</td>
100</tr>
101<tr>
102<td align="left" colspan="3">Corrected maintainers paragraph,
103Corrected stable release number</td>
104</tr>
105<tr>
106<td align="left">Revision 1.3</td>
107<td align="left">2001-07-24</td>
108<td align="left">Revised by: ppadala</td>
109</tr>
110<tr>
111<td align="left" colspan="3">Added copyright notices to main
112document (LDP license) and programs (GPL), Corrected
113printw_example.</td>
114</tr>
115<tr>
116<td align="left">Revision 1.2</td>
117<td align="left">2001-06-05</td>
118<td align="left">Revised by: ppadala</td>
119</tr>
120<tr>
121<td align="left" colspan="3">Incorporated ravi's changes. Mainly to
122introduction, menu, form, justforfun sections</td>
123</tr>
124<tr>
125<td align="left">Revision 1.1</td>
126<td align="left">2001-05-22</td>
127<td align="left">Revised by: ppadala</td>
128</tr>
129<tr>
130<td align="left" colspan="3">Added "a word about window" section,
131Added scanw_example.</td>
132</tr>
133</table>
134</div>
135<div>
136<div class="ABSTRACT"><a name="AEN67" id="AEN67"></a>
137<p><em>This document is intended to be an "All in One" guide for
138programming with ncurses and its sister libraries. We graduate from
139a simple "Hello World" program to more complex form manipulation.
140No prior experience in ncurses is assumed. Send comments to
141<a href="mailto:ppadala@gmail.com" target="_top">this
142address</a></em></p>
143</div>
144</div>
145<hr></div>
146<div class="TOC">
147<dl>
148<dt><b>Table of Contents</b></dt>
149<dt>1. <a href="#INTRO">Introduction</a></dt>
150<dd>
151<dl>
152<dt>1.1. <a href="#WHATIS">What is NCURSES?</a></dt>
153<dt>1.2. <a href="#WHATCANWEDO">What we can do with
154NCURSES</a></dt>
155<dt>1.3. <a href="#WHERETOGETIT">Where to get it</a></dt>
156<dt>1.4. <a href="#PURPOSE">Purpose/Scope of the document</a></dt>
157<dt>1.5. <a href="#ABOUTPROGRAMS">About the Programs</a></dt>
158<dt>1.6. <a href="#OTHERFORMATS">Other Formats of the
159document</a></dt>
160<dt>1.7. <a href="#CREDITS">Credits</a></dt>
161<dt>1.8. <a href="#WISHLIST">Wish List</a></dt>
162<dt>1.9. <a href="#COPYRIGHT">Copyright</a></dt>
163</dl>
164</dd>
165<dt>2. <a href="#HELLOWORLD">Hello World !!!</a></dt>
166<dd>
167<dl>
168<dt>2.1. <a href="#COMPILECURSES">Compiling With the NCURSES
169Library</a></dt>
170<dt>2.2. <a href="#DISSECTION">Dissection</a></dt>
171</dl>
172</dd>
173<dt>3. <a href="#GORY">The Gory Details</a></dt>
174<dt>4. <a href="#INIT">Initialization</a></dt>
175<dd>
176<dl>
177<dt>4.1. <a href="#ABOUTINIT">Initialization functions</a></dt>
178<dt>4.2. <a href="#RAWCBREAK">raw() and cbreak()</a></dt>
179<dt>4.3. <a href="#ECHONOECHO">echo() and noecho()</a></dt>
180<dt>4.4. <a href="#KEYPAD">keypad()</a></dt>
181<dt>4.5. <a href="#HALFDELAY">halfdelay()</a></dt>
182<dt>4.6. <a href="#MISCINIT">Miscellaneous Initialization
183functions</a></dt>
184<dt>4.7. <a href="#INITEX">An Example</a></dt>
185</dl>
186</dd>
187<dt>5. <a href="#AWORDWINDOWS">A Word about Windows</a></dt>
188<dt>6. <a href="#PRINTW">Output functions</a></dt>
189<dd>
190<dl>
191<dt>6.1. <a href="#ADDCHCLASS">addch() class of functions</a></dt>
192<dt>6.2. <a href="#AEN298">mvaddch(), waddch() and
193mvwaddch()</a></dt>
194<dt>6.3. <a href="#PRINTWCLASS">printw() class of
195functions</a></dt>
196<dt>6.4. <a href="#ADDSTRCLASS">addstr() class of
197functions</a></dt>
198<dt>6.5. <a href="#ACAUTION">A word of caution</a></dt>
199</dl>
200</dd>
201<dt>7. <a href="#SCANW">Input functions</a></dt>
202<dd>
203<dl>
204<dt>7.1. <a href="#GETCHCLASS">getch() class of functions</a></dt>
205<dt>7.2. <a href="#SCANWCLASS">scanw() class of functions</a></dt>
206<dt>7.3. <a href="#GETSTRCLASS">getstr() class of
207functions</a></dt>
208<dt>7.4. <a href="#GETSTREX">Some examples</a></dt>
209</dl>
210</dd>
211<dt>8. <a href="#ATTRIB">Attributes</a></dt>
212<dd>
213<dl>
214<dt>8.1. <a href="#ATTRIBDETAILS">The details</a></dt>
215<dt>8.2. <a href="#ATTRONVSATTRSET">attron() vs attrset()</a></dt>
216<dt>8.3. <a href="#ATTR_GET">attr_get()</a></dt>
217<dt>8.4. <a href="#ATTR_FUNCS">attr_ functions</a></dt>
218<dt>8.5. <a href="#WATTRFUNCS">wattr functions</a></dt>
219<dt>8.6. <a href="#CHGAT">chgat() functions</a></dt>
220</dl>
221</dd>
222<dt>9. <a href="#WINDOWS">Windows</a></dt>
223<dd>
224<dl>
225<dt>9.1. <a href="#WINDOWBASICS">The basics</a></dt>
226<dt>9.2. <a href="#LETBEWINDOW">Let there be a Window !!!</a></dt>
227<dt>9.3. <a href="#BORDEREXEXPL">Explanation</a></dt>
228<dt>9.4. <a href="#OTHERSTUFF">The other stuff in the
229example</a></dt>
230<dt>9.5. <a href="#OTHERBORDERFUNCS">Other Border
231functions</a></dt>
232</dl>
233</dd>
234<dt>10. <a href="#COLOR">Colors</a></dt>
235<dd>
236<dl>
237<dt>10.1. <a href="#COLORBASICS">The basics</a></dt>
238<dt>10.2. <a href="#CHANGECOLORDEFS">Changing Color
239Definitions</a></dt>
240<dt>10.3. <a href="#COLORCONTENT">Color Content</a></dt>
241</dl>
242</dd>
243<dt>11. <a href="#KEYS">Interfacing with the key board</a></dt>
244<dd>
245<dl>
246<dt>11.1. <a href="#KEYSBASICS">The Basics</a></dt>
247<dt>11.2. <a href="#SIMPLEKEYEX">A Simple Key Usage
248example</a></dt>
249</dl>
250</dd>
251<dt>12. <a href="#MOUSE">Interfacing with the mouse</a></dt>
252<dd>
253<dl>
254<dt>12.1. <a href="#MOUSEBASICS">The Basics</a></dt>
255<dt>12.2. <a href="#GETTINGEVENTS">Getting the events</a></dt>
256<dt>12.3. <a href="#MOUSETOGETHER">Putting it all Together</a></dt>
257<dt>12.4. <a href="#MISCMOUSEFUNCS">Miscellaneous
258Functions</a></dt>
259</dl>
260</dd>
261<dt>13. <a href="#SCREEN">Screen Manipulation</a></dt>
262<dd>
263<dl>
264<dt>13.1. <a href="#GETYX">getyx() functions</a></dt>
265<dt>13.2. <a href="#SCREENDUMP">Screen Dumping</a></dt>
266<dt>13.3. <a href="#WINDOWDUMP">Window Dumping</a></dt>
267</dl>
268</dd>
269<dt>14. <a href="#MISC">Miscellaneous features</a></dt>
270<dd>
271<dl>
272<dt>14.1. <a href="#CURSSET">curs_set()</a></dt>
273<dt>14.2. <a href="#TEMPLEAVE">Temporarily Leaving Curses
274mode</a></dt>
275<dt>14.3. <a href="#ACSVARS">ACS_ variables</a></dt>
276</dl>
277</dd>
278<dt>15. <a href="#OTHERLIB">Other libraries</a></dt>
279<dt>16. <a href="#PANELS">Panel Library</a></dt>
280<dd>
281<dl>
282<dt>16.1. <a href="#PANELBASICS">The Basics</a></dt>
283<dt>16.2. <a href="#COMPILEPANELS">Compiling With the Panels
284Library</a></dt>
285<dt>16.3. <a href="#PANELBROWSING">Panel Window Browsing</a></dt>
286<dt>16.4. <a href="#USERPTRUSING">Using User Pointers</a></dt>
287<dt>16.5. <a href="#PANELMOVERESIZE">Moving and Resizing
288Panels</a></dt>
289<dt>16.6. <a href="#PANELSHOWHIDE">Hiding and Showing
290Panels</a></dt>
291<dt>16.7. <a href="#PANELABOVE">panel_above() and panel_below()
292Functions</a></dt>
293</dl>
294</dd>
295<dt>17. <a href="#MENUS">Menus Library</a></dt>
296<dd>
297<dl>
298<dt>17.1. <a href="#MENUBASICS">The Basics</a></dt>
299<dt>17.2. <a href="#COMPILEMENUS">Compiling With the Menu
300Library</a></dt>
301<dt>17.3. <a href="#MENUDRIVER">Menu Driver: The work horse of the
302menu system</a></dt>
303<dt>17.4. <a href="#MENUWINDOWS">Menu Windows</a></dt>
304<dt>17.5. <a href="#SCROLLMENUS">Scrolling Menus</a></dt>
305<dt>17.6. <a href="#MULTICOLUMN">Multi Columnar Menus</a></dt>
306<dt>17.7. <a href="#MULTIVALUEMENUS">Multi Valued Menus</a></dt>
307<dt>17.8. <a href="#MENUOPT">Menu Options</a></dt>
308<dt>17.9. <a href="#MENUUSERPTR">The useful User Pointer</a></dt>
309</dl>
310</dd>
311<dt>18. <a href="#FORMS">Forms Library</a></dt>
312<dd>
313<dl>
314<dt>18.1. <a href="#FORMBASICS">The Basics</a></dt>
315<dt>18.2. <a href="#COMPILEFORMS">Compiling With the Forms
316Library</a></dt>
317<dt>18.3. <a href="#PLAYFIELDS">Playing with Fields</a></dt>
318<dt>18.4. <a href="#FORMWINDOWS">Form Windows</a></dt>
319<dt>18.5. <a href="#FILEDVALIDATE">Field Validation</a></dt>
320<dt>18.6. <a href="#FORMDRIVER">Form Driver: The work horse of the
321forms system</a></dt>
322</dl>
323</dd>
324<dt>19. <a href="#TOOLS">Tools and Widget Libraries</a></dt>
325<dd>
326<dl>
327<dt>19.1. <a href="#CDK">CDK (Curses Development Kit)</a></dt>
328<dt>19.2. <a href="#DIALOG">The dialog</a></dt>
329<dt>19.3. <a href="#PERLCURSES">Perl Curses Modules CURSES::FORM
330and CURSES::WIDGETS</a></dt>
331</dl>
332</dd>
333<dt>20. <a href="#JUSTFORFUN">Just For Fun !!!</a></dt>
334<dd>
335<dl>
336<dt>20.1. <a href="#GAMEOFLIFE">The Game of Life</a></dt>
337<dt>20.2. <a href="#MAGIC">Magic Square</a></dt>
338<dt>20.3. <a href="#HANOI">Towers of Hanoi</a></dt>
339<dt>20.4. <a href="#QUEENS">Queens Puzzle</a></dt>
340<dt>20.5. <a href="#SHUFFLE">Shuffle</a></dt>
341<dt>20.6. <a href="#TT">Typing Tutor</a></dt>
342</dl>
343</dd>
344<dt>21. <a href="#REF">References</a></dt>
345</dl>
346</div>
347<div class="SECT1">
348<h2 class="SECT1"><a name="INTRO" id="INTRO">1.
349Introduction</a></h2>
350<p>In the olden days of teletype terminals, terminals were away
351from computers and were connected to them through serial cables.
352The terminals could be configured by sending a series of bytes. All
353the capabilities (such as moving the cursor to a new location,
354erasing part of the screen, scrolling the screen, changing modes
355etc.) of terminals could be accessed through these series of bytes.
356These control seeuqnces are usually called escape sequences,
357because they start with an escape(0x1B) character. Even today, with
358proper emulation, we can send escape sequences to the emulator and
359achieve the same effect on a terminal window.</p>
360<p>Suppose you wanted to print a line in color. Try typing this on
361your console.</p>
362<table border="0" bgcolor="#E0E0E0" width="100%">
363<tr>
364<td>
365<pre class="PROGRAMLISTING">
366<font color="#000000">echo "^[[0;31;40mIn Color"</font>
367</pre></td>
368</tr>
369</table>
370<p>The first character is an escape character, which looks like two
371characters ^ and [. To be able to print it, you have to press
372CTRL+V and then the ESC key. All the others are normal printable
373characters. You should be able to see the string "In Color" in red.
374It stays that way and to revert back to the original mode type
375this.</p>
376<table border="0" bgcolor="#E0E0E0" width="100%">
377<tr>
378<td>
379<pre class="PROGRAMLISTING">
380<font color="#000000">echo "^[[0;37;40m"</font>
381</pre></td>
382</tr>
383</table>
384<p>Now, what do these magic characters mean? Difficult to
385comprehend? They might even be different for different terminals.
386So the designers of UNIX invented a mechanism named <var class=
387"LITERAL">termcap</var>. It is a file that lists all the
388capabilities of a particular terminal, along with the escape
389sequences needed to achieve a particular effect. In the later
390years, this was replaced by <var class="LITERAL">terminfo</var>.
391Without delving too much into details, this mechanism allows
392application programs to query the terminfo database and obtain the
393control characters to be sent to a terminal or terminal
394emulator.</p>
395<div class="SECT2">
396<hr>
397<h3 class="SECT2"><a name="WHATIS" id="WHATIS">1.1. What is
398NCURSES?</a></h3>
399<p>You might be wondering, what the import of all this technical
400gibberish is. In the above scenario, every application program is
401supposed to query the terminfo and perform the necessary stuff
402(sending control characters etc.). It soon became difficult to
403manage this complexity and this gave birth to 'CURSES'. Curses is a
404pun on the name "cursor optimization". The Curses library forms a
405wrapper over working with raw terminal codes, and provides highly
406flexible and efficient API (Application Programming Interface). It
407provides functions to move the cursor, create windows, produce
408colors, play with mouse etc. The application programs need not
409worry about the underlying terminal capabilities.</p>
410<p>So what is NCURSES? NCURSES is a clone of the original System V
411Release 4.0 (SVr4) curses. It is a freely distributable library,
412fully compatible with older version of curses. In short, it is a
413library of functions that manages an application's display on
414character-cell terminals. In the remainder of the document, the
415terms curses and ncurses are used interchangeably.</p>
416<p>A detailed history of NCURSES can be found in the NEWS file from
417the source distribution. The current package is maintained by
418<a href="mailto:dickey@his.com" target="_top">Thomas Dickey</a>.
419You can contact the maintainers at <a href=
420"mailto:bug-ncurses@gnu.org" target=
421"_top">bug-ncurses@gnu.org</a>.</p>
422</div>
423<div class="SECT2">
424<hr>
425<h3 class="SECT2"><a name="WHATCANWEDO" id="WHATCANWEDO">1.2. What
426we can do with NCURSES</a></h3>
427<p>NCURSES not only creates a wrapper over terminal capabilities,
428but also gives a robust framework to create nice looking UI (User
429Interface)s in text mode. It provides functions to create windows
430etc. Its sister libraries panel, menu and form provide an extension
431to the basic curses library. These libraries usually come along
432with curses. One can create applications that contain multiple
433windows, menus, panels and forms. Windows can be managed
434independently, can provide 'scrollability' and even can be
435hidden.</p>
436<p>Menus provide the user with an easy command selection option.
437Forms allow the creation of easy-to-use data entry and display
438windows. Panels extend the capabilities of ncurses to deal with
439overlapping and stacked windows.</p>
440<p>These are just some of the basic things we can do with ncurses.
441As we move along, We will see all the capabilities of these
442libraries.</p>
443</div>
444<div class="SECT2">
445<hr>
446<h3 class="SECT2"><a name="WHERETOGETIT" id="WHERETOGETIT">1.3.
447Where to get it</a></h3>
448<p>All right, now that you know what you can do with ncurses, you
449must be rearing to get started. NCURSES is usually shipped with
450your installation. In case you don't have the library or want to
451compile it on your own, read on.</p>
452<p><em>Compiling the package</em></p>
453<p>NCURSES can be obtained from <a href=
454"ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz" target=
455"_top">ftp://ftp.gnu.org/pub/gnu/ncurses/ncurses.tar.gz</a> or any
456of the ftp sites mentioned in <a href=
457"http://www.gnu.org/order/ftp.html" target=
458"_top">http://www.gnu.org/order/ftp.html</a>.</p>
459<p>Read the README and INSTALL files for details on to how to
460install it. It usually involves the following operations.</p>
461<table border="0" bgcolor="#E0E0E0" width="100%">
462<tr>
463<td>
464<pre class="PROGRAMLISTING">
465<font color=
466"#000000"> tar zxvf ncurses&lt;version&gt;.tar.gz # unzip and untar the archive
467 cd ncurses&lt;version&gt; # cd to the directory
468 ./configure # configure the build according to your
469 # environment
470 make # make it
471 su root # become root
472 make install # install it</font>
473</pre></td>
474</tr>
475</table>
476<p><em>Using the RPM</em></p>
477<p>NCURSES RPM can be found and downloaded from <a href=
478"http://rpmfind.net" target="_top">http://rpmfind.net</a> . The RPM
479can be installed with the following command after becoming
480root.</p>
481<table border="0" bgcolor="#E0E0E0" width="100%">
482<tr>
483<td>
484<pre class="PROGRAMLISTING">
485<font color="#000000"> rpm -i &lt;downloaded rpm&gt;</font>
486</pre></td>
487</tr>
488</table>
489</div>
490<div class="SECT2">
491<hr>
492<h3 class="SECT2"><a name="PURPOSE" id="PURPOSE">1.4. Purpose/Scope
493of the document</a></h3>
494<p>This document is intended to be a "All in One" guide for
495programming with ncurses and its sister libraries. We graduate from
496a simple "Hello World" program to more complex form manipulation.
497No prior experience in ncurses is assumed. The writing is informal,
498but a lot of detail is provided for each of the examples.</p>
499</div>
500<div class="SECT2">
501<hr>
502<h3 class="SECT2"><a name="ABOUTPROGRAMS" id="ABOUTPROGRAMS">1.5.
503About the Programs</a></h3>
504<p>All the programs in the document are available in zipped form
505<a href=
506"http://www.tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs.tar.gz"
507target="_top">here</a>. Unzip and untar it. The directory structure
508looks like this.</p>
509<table border="0" bgcolor="#E0E0E0" width="100%">
510<tr>
511<td>
512<pre class="PROGRAMLISTING">
513<font color="#000000">ncurses
514 |
515 |----&gt; JustForFun -- just for fun programs
516 |----&gt; basics -- basic programs
517 |----&gt; demo -- output files go into this directory after make
518 | |
519 | |----&gt; exe -- exe files of all example programs
520 |----&gt; forms -- programs related to form library
521 |----&gt; menus -- programs related to menus library
522 |----&gt; panels -- programs related to panels library
523 |----&gt; perl -- perl equivalents of the examples (contributed
524 | by Anuradha Ratnaweera)
525 |----&gt; Makefile -- the top level Makefile
526 |----&gt; README -- the top level README file. contains instructions
527 |----&gt; COPYING -- copyright notice</font>
528</pre></td>
529</tr>
530</table>
531<p>The individual directories contain the following files.</p>
532<table border="0" bgcolor="#E0E0E0" width="100%">
533<tr>
534<td>
535<pre class="PROGRAMLISTING">
536<font color="#000000">Description of files in each directory
537--------------------------------------
538JustForFun
539 |
540 |----&gt; hanoi.c -- The Towers of Hanoi Solver
541 |----&gt; life.c -- The Game of Life demo
542 |----&gt; magic.c -- An Odd Order Magic Square builder
543 |----&gt; queens.c -- The famous N-Queens Solver
544 |----&gt; shuffle.c -- A fun game, if you have time to kill
545 |----&gt; tt.c -- A very trivial typing tutor
546
547 basics
548 |
549 |----&gt; acs_vars.c -- ACS_ variables example
550 |----&gt; hello_world.c -- Simple "Hello World" Program
551 |----&gt; init_func_example.c -- Initialization functions example
552 |----&gt; key_code.c -- Shows the scan code of the key pressed
553 |----&gt; mouse_menu.c -- A menu accessible by mouse
554 |----&gt; other_border.c -- Shows usage of other border functions apa
555 | -- rt from box()
556 |----&gt; printw_example.c -- A very simple printw() example
557 |----&gt; scanw_example.c -- A very simple getstr() example
558 |----&gt; simple_attr.c -- A program that can print a c file with
559 | -- comments in attribute
560 |----&gt; simple_color.c -- A simple example demonstrating colors
561 |----&gt; simple_key.c -- A menu accessible with keyboard UP, DOWN
562 | -- arrows
563 |----&gt; temp_leave.c -- Demonstrates temporarily leaving curses mode
564 |----&gt; win_border.c -- Shows Creation of windows and borders
565 |----&gt; with_chgat.c -- chgat() usage example
566
567 forms
568 |
569 |----&gt; form_attrib.c -- Usage of field attributes
570 |----&gt; form_options.c -- Usage of field options
571 |----&gt; form_simple.c -- A simple form example
572 |----&gt; form_win.c -- Demo of windows associated with forms
573
574 menus
575 |
576 |----&gt; menu_attrib.c -- Usage of menu attributes
577 |----&gt; menu_item_data.c -- Usage of item_name() etc.. functions
578 |----&gt; menu_multi_column.c -- Creates multi columnar menus
579 |----&gt; menu_scroll.c -- Demonstrates scrolling capability of menus
580 |----&gt; menu_simple.c -- A simple menu accessed by arrow keys
581 |----&gt; menu_toggle.c -- Creates multi valued menus and explains
582 | -- REQ_TOGGLE_ITEM
583 |----&gt; menu_userptr.c -- Usage of user pointer
584 |----&gt; menu_win.c -- Demo of windows associated with menus
585
586 panels
587 |
588 |----&gt; panel_browse.c -- Panel browsing through tab. Usage of user
589 | -- pointer
590 |----&gt; panel_hide.c -- Hiding and Un hiding of panels
591 |----&gt; panel_resize.c -- Moving and resizing of panels
592 |----&gt; panel_simple.c -- A simple panel example
593
594 perl
595 |----&gt; 01-10.pl -- Perl equivalents of first ten example programs</font>
596</pre></td>
597</tr>
598</table>
599<p>There is a top level Makefile included in the main directory. It
600builds all the files and puts the ready-to-use exes in demo/exe
601directory. You can also do selective make by going into the
602corresponding directory. Each directory contains a README file
603explaining the purpose of each c file in the directory.</p>
604<p>For every example, I have included path name for the file
605relative to the examples directory.</p>
606<p>If you prefer browsing individual programs, point your browser
607to <a href=
608"http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/"
609target=
610"_top">http://tldp.org/HOWTO/NCURSES-Programming-HOWTO/ncurses_programs/</a></p>
611<p>All the programs are released under the same license that is
612used by ncurses (MIT-style). This gives you the ability to do
613pretty much anything other than claiming them as yours. Feel free
614to use them in your programs as appropriate.</p>
615</div>
616<div class="SECT2">
617<hr>
618<h3 class="SECT2"><a name="OTHERFORMATS" id="OTHERFORMATS">1.6.
619Other Formats of the document</a></h3>
620<p>This howto is also availabe in various other formats on the
621tldp.org site. Here are the links to other formats of this
622document.</p>
623<div class="SECT3">
624<hr>
625<h4 class="SECT3"><a name="LISTFORMATS" id="LISTFORMATS">1.6.1.
626Readily available formats from tldp.org</a></h4>
627<ul>
628<li>
629<p><a href=
630"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/pdf/NCURSES-Programming-HOWTO.pdf"
631target="_top">Acrobat PDF Format</a></p>
632</li>
633<li>
634<p><a href=
635"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/ps/NCURSES-Programming-HOWTO.ps.gz"
636target="_top">PostScript Format</a></p>
637</li>
638<li>
639<p><a href=
640"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html/NCURSES-Programming-HOWTO-html.tar.gz"
641target="_top">In Multiple HTML pages</a></p>
642</li>
643<li>
644<p><a href=
645"http://www.ibiblio.org/pub/Linux/docs/HOWTO/other-formats/html_single/NCURSES-Programming-HOWTO.html"
646target="_top">In One big HTML format</a></p>
647</li>
648</ul>
649</div>
650<div class="SECT3">
651<hr>
652<h4 class="SECT3"><a name="BUILDSOURCE" id="BUILDSOURCE">1.6.2.
653Building from source</a></h4>
654<p>If above links are broken or if you want to experiment with sgml
655read on.</p>
656<table border="0" bgcolor="#E0E0E0" width="100%">
657<tr>
658<td>
659<pre class="PROGRAMLISTING">
660<font color=
661"#000000">&#13; Get both the source and the tar,gzipped programs, available at
662 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
663 NCURSES-HOWTO/NCURSES-Programming-HOWTO.sgml
664 http://cvsview.tldp.org/index.cgi/LDP/howto/docbook/
665 NCURSES-HOWTO/ncurses_programs.tar.gz
666
667 Unzip ncurses_programs.tar.gz with
668 tar zxvf ncurses_programs.tar.gz
669
670 Use jade to create various formats. For example if you just want to create
671 the multiple html files, you would use
672 jade -t sgml -i html -d &lt;path to docbook html stylesheet&gt;
673 NCURSES-Programming-HOWTO.sgml
674 to get pdf, first create a single html file of the HOWTO with
675 jade -t sgml -i html -d &lt;path to docbook html stylesheet&gt; -V nochunks
676 NCURSES-Programming-HOWTO.sgml &gt; NCURSES-ONE-BIG-FILE.html
677 then use htmldoc to get pdf file with
678 htmldoc --size universal -t pdf --firstpage p1 -f &lt;output file name.pdf&gt;
679 NCURSES-ONE-BIG-FILE.html
680 for ps, you would use
681 htmldoc --size universal -t ps --firstpage p1 -f &lt;output file name.ps&gt;
682 NCURSES-ONE-BIG-FILE.html</font>
683</pre></td>
684</tr>
685</table>
686<p>See <a href="http://www.tldp.org/LDP/LDP-Author-Guide/" target=
687"_top">LDP Author guide</a> for more details. If all else failes,
688mail me at <a href="ppadala@gmail.com" target=
689"_top">ppadala@gmail.com</a></p>
690</div>
691</div>
692<div class="SECT2">
693<hr>
694<h3 class="SECT2"><a name="CREDITS" id="CREDITS">1.7.
695Credits</a></h3>
696<p>I thank <a href="mailto:sharath_1@usa.net" target=
697"_top">Sharath</a> and Emre Akbas for helping me with few sections.
698The introduction was initially written by sharath. I rewrote it
699with few excerpts taken from his initial work. Emre helped in
700writing printw and scanw sections.</p>
701<p>Perl equivalents of the example programs are contributed by
702<a href="mailto:Aratnaweera@virtusa.com" target="_top">Anuradha
703Ratnaweera</a>.</p>
704<p>Then comes <a href="mailto:parimi@ece.arizona.edu" target=
705"_top">Ravi Parimi</a>, my dearest friend, who has been on this
706project before even one line was written. He constantly bombarded
707me with suggestions and patiently reviewed the whole text. He also
708checked each program on Linux and Solaris.</p>
709</div>
710<div class="SECT2">
711<hr>
712<h3 class="SECT2"><a name="WISHLIST" id="WISHLIST">1.8. Wish
713List</a></h3>
714<p>This is the wish list, in the order of priority. If you have a
715wish or you want to work on completing the wish, mail <a href=
716"mailto:ppadala@gmail.com" target="_top">me</a>.</p>
717<ul>
718<li>
719<p>Add examples to last parts of forms section.</p>
720</li>
721<li>
722<p>Prepare a Demo showing all the programs and allow the user to
723browse through description of each program. Let the user compile
724and see the program in action. A dialog based interface is
725preferred.</p>
726</li>
727<li>
728<p>Add debug info. _tracef, _tracemouse stuff.</p>
729</li>
730<li>
731<p>Accessing termcap, terminfo using functions provided by ncurses
732package.</p>
733</li>
734<li>
735<p>Working on two terminals simultaneously.</p>
736</li>
737<li>
738<p>Add more stuff to miscellaneous section.</p>
739</li>
740</ul>
741</div>
742<div class="SECT2">
743<hr>
744<h3 class="SECT2"><a name="COPYRIGHT" id="COPYRIGHT">1.9.
745Copyright</a></h3>
746<p>Copyright &copy; 2001 by Pradeep Padala.</p>
747<p>Permission is hereby granted, free of charge, to any person
748obtaining a copy of this software and associated documentation
749files (the "Software"), to deal in the Software without
750restriction, including without limitation the rights to use, copy,
751modify, merge, publish, distribute, distribute with modifications,
752sublicense, and/or sell copies of the Software, and to permit
753persons to whom the Software is furnished to do so, subject to the
754following conditions:</p>
755<p>The above copyright notice and this permission notice shall be
756included in all copies or substantial portions of the Software.</p>
757<p>THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
758EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
759MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
760NONINFRINGEMENT. IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE
761LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
762ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
763CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
764SOFTWARE.</p>
765<p>Except as contained in this notice, the name(s) of the above
766copyright holders shall not be used in advertising or otherwise to
767promote the sale, use or other dealings in this Software without
768prior written authorization.</p>
769</div>
770</div>
771<div class="SECT1">
772<hr>
773<h2 class="SECT1"><a name="HELLOWORLD" id="HELLOWORLD">2. Hello
774World !!!</a></h2>
775<p>Welcome to the world of curses. Before we plunge into the
776library and look into its various features, let's write a simple
777program and say hello to the world.</p>
778<div class="SECT2">
779<hr>
780<h3 class="SECT2"><a name="COMPILECURSES" id="COMPILECURSES">2.1.
781Compiling With the NCURSES Library</a></h3>
782<p>To use ncurses library functions, you have to include ncurses.h
783in your programs. To link the program with ncurses the flag
784-lncurses should be added.</p>
785<table border="0" bgcolor="#E0E0E0" width="100%">
786<tr>
787<td>
788<pre class="PROGRAMLISTING">
789<font color="#000000"> #include &lt;ncurses.h&gt;
790 .
791 .
792 .
793
794 compile and link: gcc &lt;program file&gt; -lncurses</font>
795</pre></td>
796</tr>
797</table>
798<div class="EXAMPLE"><a name="BHW" id="BHW"></a>
799<p><b>Example 1. The Hello World !!! Program</b></p>
800<table border="0" bgcolor="#E0E0E0" width="100%">
801<tr>
802<td>
803<pre class="PROGRAMLISTING">
804<font color="#000000"><span class=
805"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
806
807int main()
808{
809 initscr(); /* Start curses mode */
810 printw("Hello World !!!"); /* Print Hello World */
811 refresh(); /* Print it on to the real screen */
812 getch(); /* Wait for user input */
813 endwin(); /* End curses mode */
814
815 return 0;
816}</span></font>
817</pre></td>
818</tr>
819</table>
820</div>
821</div>
822<div class="SECT2">
823<hr>
824<h3 class="SECT2"><a name="DISSECTION" id="DISSECTION">2.2.
825Dissection</a></h3>
826<p>The above program prints "Hello World !!!" to the screen and
827exits. This program shows how to initialize curses and do screen
828manipulation and end curses mode. Let's dissect it line by
829line.</p>
830<div class="SECT3">
831<hr>
832<h4 class="SECT3"><a name="ABOUT-INITSCR" id="ABOUT-INITSCR">2.2.1.
833About initscr()</a></h4>
834<p>The function initscr() initializes the terminal in curses mode.
835In some implementations, it clears the screen and presents a blank
836screen. To do any screen manipulation using curses package this has
837to be called first. This function initializes the curses system and
838allocates memory for our present window (called <var class=
839"LITERAL">stdscr</var>) and some other data-structures. Under
840extreme cases this function might fail due to insufficient memory
841to allocate memory for curses library's data structures.</p>
842<p>After this is done, we can do a variety of initializations to
843customize our curses settings. These details will be explained
844<a href="#INIT">later</a> .</p>
845</div>
846<div class="SECT3">
847<hr>
848<h4 class="SECT3"><a name="MYST-REFRESH" id="MYST-REFRESH">2.2.2.
849The mysterious refresh()</a></h4>
850<p>The next line printw prints the string "Hello World !!!" on to
851the screen. This function is analogous to normal printf in all
852respects except that it prints the data on a window called stdscr
853at the current (y,x) co-ordinates. Since our present co-ordinates
854are at 0,0 the string is printed at the left hand corner of the
855window.</p>
856<p>This brings us to that mysterious refresh(). Well, when we
857called printw the data is actually written to an imaginary window,
858which is not updated on the screen yet. The job of printw is to
859update a few flags and data structures and write the data to a
860buffer corresponding to stdscr. In order to show it on the screen,
861we need to call refresh() and tell the curses system to dump the
862contents on the screen.</p>
863<p>The philosophy behind all this is to allow the programmer to do
864multiple updates on the imaginary screen or windows and do a
865refresh once all his screen update is done. refresh() checks the
866window and updates only the portion which has been changed. This
867improves performance and offers greater flexibility too. But, it is
868sometimes frustrating to beginners. A common mistake committed by
869beginners is to forget to call refresh() after they did some update
870through printw() class of functions. I still forget to add it
871sometimes :-)</p>
872</div>
873<div class="SECT3">
874<hr>
875<h4 class="SECT3"><a name="ABOUT-ENDWIN" id="ABOUT-ENDWIN">2.2.3.
876About endwin()</a></h4>
877<p>And finally don't forget to end the curses mode. Otherwise your
878terminal might behave strangely after the program quits. endwin()
879frees the memory taken by curses sub-system and its data structures
880and puts the terminal in normal mode. This function must be called
881after you are done with the curses mode.</p>
882</div>
883</div>
884</div>
885<div class="SECT1">
886<hr>
887<h2 class="SECT1"><a name="GORY" id="GORY">3. The Gory
888Details</a></h2>
889<p>Now that we have seen how to write a simple curses program let's
890get into the details. There are many functions that help customize
891what you see on screen and many features which can be put to full
892use.</p>
893<p>Here we go...</p>
894</div>
895<div class="SECT1">
896<hr>
897<h2 class="SECT1"><a name="INIT" id="INIT">4.
898Initialization</a></h2>
899<p>We now know that to initialize curses system the function
900initscr() has to be called. There are functions which can be called
901after this initialization to customize our curses session. We may
902ask the curses system to set the terminal in raw mode or initialize
903color or initialize the mouse etc.. Let's discuss some of the
904functions that are normally called immediately after initscr();</p>
905<div class="SECT2">
906<hr>
907<h3 class="SECT2"><a name="ABOUTINIT" id="ABOUTINIT">4.1.
908Initialization functions</a></h3>
909</div>
910<div class="SECT2">
911<hr>
912<h3 class="SECT2"><a name="RAWCBREAK" id="RAWCBREAK">4.2. raw() and
913cbreak()</a></h3>
914<p>Normally the terminal driver buffers the characters a user types
915until a new line or carriage return is encountered. But most
916programs require that the characters be available as soon as the
917user types them. The above two functions are used to disable line
918buffering. The difference between these two functions is in the way
919control characters like suspend (CTRL-Z), interrupt and quit
920(CTRL-C) are passed to the program. In the raw() mode these
921characters are directly passed to the program without generating a
922signal. In the <var class="LITERAL">cbreak()</var> mode these
923control characters are interpreted as any other character by the
924terminal driver. I personally prefer to use raw() as I can exercise
925greater control over what the user does.</p>
926</div>
927<div class="SECT2">
928<hr>
929<h3 class="SECT2"><a name="ECHONOECHO" id="ECHONOECHO">4.3. echo()
930and noecho()</a></h3>
931<p>These functions control the echoing of characters typed by the
932user to the terminal. <var class="LITERAL">noecho()</var> switches
933off echoing. The reason you might want to do this is to gain more
934control over echoing or to suppress unnecessary echoing while
935taking input from the user through the getch() etc. functions. Most
936of the interactive programs call <var class=
937"LITERAL">noecho()</var> at initialization and do the echoing of
938characters in a controlled manner. It gives the programmer the
939flexibility of echoing characters at any place in the window
940without updating current (y,x) co-ordinates.</p>
941</div>
942<div class="SECT2">
943<hr>
944<h3 class="SECT2"><a name="KEYPAD" id="KEYPAD">4.4.
945keypad()</a></h3>
946<p>This is my favorite initialization function. It enables the
947reading of function keys like F1, F2, arrow keys etc. Almost every
948interactive program enables this, as arrow keys are a major part of
949any User Interface. Do <var class="LITERAL">keypad(stdscr,
950TRUE)</var> to enable this feature for the regular screen (stdscr).
951You will learn more about key management in later sections of this
952document.</p>
953</div>
954<div class="SECT2">
955<hr>
956<h3 class="SECT2"><a name="HALFDELAY" id="HALFDELAY">4.5.
957halfdelay()</a></h3>
958<p>This function, though not used very often, is a useful one at
959times. halfdelay()is called to enable the half-delay mode, which is
960similar to the cbreak() mode in that characters typed are
961immediately available to program. However, it waits for 'X' tenths
962of a second for input and then returns ERR, if no input is
963available. 'X' is the timeout value passed to the function
964halfdelay(). This function is useful when you want to ask the user
965for input, and if he doesn't respond with in certain time, we can
966do some thing else. One possible example is a timeout at the
967password prompt.</p>
968</div>
969<div class="SECT2">
970<hr>
971<h3 class="SECT2"><a name="MISCINIT" id="MISCINIT">4.6.
972Miscellaneous Initialization functions</a></h3>
973<p>There are few more functions which are called at initialization
974to customize curses behavior. They are not used as extensively as
975those mentioned above. Some of them are explained where
976appropriate.</p>
977</div>
978<div class="SECT2">
979<hr>
980<h3 class="SECT2"><a name="INITEX" id="INITEX">4.7. An
981Example</a></h3>
982<p>Let's write a program which will clarify the usage of these
983functions.</p>
984<div class="EXAMPLE"><a name="BINFU" id="BINFU"></a>
985<p><b>Example 2. Initialization Function Usage example</b></p>
986<table border="0" bgcolor="#E0E0E0" width="100%">
987<tr>
988<td>
989<pre class="PROGRAMLISTING">
990<font color="#000000"><span class=
991"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
992
993int main()
994{ int ch;
995
996 initscr(); /* Start curses mode */
997 raw(); /* Line buffering disabled */
998 keypad(stdscr, TRUE); /* We get F1, F2 etc.. */
999 noecho(); /* Don't echo() while we do getch */
1000
1001 printw("Type any character to see it in bold\n");
1002 ch = getch(); /* If raw() hadn't been called
1003 * we have to press enter before it
1004 * gets to the program */
1005 if(ch == KEY_F(1)) /* Without keypad enabled this will */
1006 printw("F1 Key pressed");/* not get to us either */
1007 /* Without noecho() some ugly escape
1008 * charachters might have been printed
1009 * on screen */
1010 else
1011 { printw("The pressed key is ");
1012 attron(A_BOLD);
1013 printw("%c", ch);
1014 attroff(A_BOLD);
1015 }
1016 refresh(); /* Print it on to the real screen */
1017 getch(); /* Wait for user input */
1018 endwin(); /* End curses mode */
1019
1020 return 0;
1021}</span></font>
1022</pre></td>
1023</tr>
1024</table>
1025</div>
1026<p>This program is self-explanatory. But I used functions which
1027aren't explained yet. The function <var class=
1028"LITERAL">getch()</var> is used to get a character from user. It is
1029equivalent to normal <var class="LITERAL">getchar()</var> except
1030that we can disable the line buffering to avoid &lt;enter&gt; after
1031input. Look for more about <var class="LITERAL">getch()</var>and
1032reading keys in the <a href="#KEYS">key management section</a> .
1033The functions attron and attroff are used to switch some attributes
1034on and off respectively. In the example I used them to print the
1035character in bold. These functions are explained in detail
1036later.</p>
1037</div>
1038</div>
1039<div class="SECT1">
1040<hr>
1041<h2 class="SECT1"><a name="AWORDWINDOWS" id="AWORDWINDOWS">5. A
1042Word about Windows</a></h2>
1043<p>Before we plunge into the myriad ncurses functions, let me clear
1044few things about windows. Windows are explained in detail in
1045following <a href="#WINDOWS">sections</a></p>
1046<p>A Window is an imaginary screen defined by curses system. A
1047window does not mean a bordered window which you usually see on
1048Win9X platforms. When curses is initialized, it creates a default
1049window named <var class="LITERAL">stdscr</var> which represents
1050your 80x25 (or the size of window in which you are running) screen.
1051If you are doing simple tasks like printing few strings, reading
1052input etc., you can safely use this single window for all of your
1053purposes. You can also create windows and call functions which
1054explicitly work on the specified window.</p>
1055<p>For example, if you call</p>
1056<table border="0" bgcolor="#E0E0E0" width="100%">
1057<tr>
1058<td>
1059<pre class="PROGRAMLISTING">
1060<font color="#000000"> printw("Hi There !!!");
1061 refresh();</font>
1062</pre></td>
1063</tr>
1064</table>
1065<p>It prints the string on stdscr at the present cursor position.
1066Similarly the call to refresh(), works on stdscr only.</p>
1067<p>Say you have created <a href="#WINDOWS">windows</a> then you
1068have to call a function with a 'w' added to the usual function.</p>
1069<table border="0" bgcolor="#E0E0E0" width="100%">
1070<tr>
1071<td>
1072<pre class="PROGRAMLISTING">
1073<font color="#000000"> wprintw(win, "Hi There !!!");
1074 wrefresh(win);</font>
1075</pre></td>
1076</tr>
1077</table>
1078<p>As you will see in the rest of the document, naming of functions
1079follow the same convention. For each function there usually are
1080three more functions.</p>
1081<table border="0" bgcolor="#E0E0E0" width="100%">
1082<tr>
1083<td>
1084<pre class="PROGRAMLISTING">
1085<font color=
1086"#000000"> printw(string); /* Print on stdscr at present cursor position */
1087 mvprintw(y, x, string);/* Move to (y, x) then print string */
1088 wprintw(win, string); /* Print on window win at present cursor position */
1089 /* in the window */
1090 mvwprintw(win, y, x, string); /* Move to (y, x) relative to window */
1091 /* co-ordinates and then print */</font>
1092</pre></td>
1093</tr>
1094</table>
1095<p>Usually the w-less functions are macros which expand to
1096corresponding w-function with stdscr as the window parameter.</p>
1097</div>
1098<div class="SECT1">
1099<hr>
1100<h2 class="SECT1"><a name="PRINTW" id="PRINTW">6. Output
1101functions</a></h2>
1102<p>I guess you can't wait any more to see some action. Back to our
1103odyssey of curses functions. Now that curses is initialized, let's
1104interact with world.</p>
1105<p>There are three classes of functions which you can use to do
1106output on screen.</p>
1107<ol type="1">
1108<li>
1109<p>addch() class: Print single character with attributes</p>
1110</li>
1111<li>
1112<p>printw() class: Print formatted output similar to printf()</p>
1113</li>
1114<li>
1115<p>addstr() class: Print strings</p>
1116</li>
1117</ol>
1118<p>These functions can be used interchangeably and it's a matter of
1119style as to which class is used. Let's see each one in detail.</p>
1120<div class="SECT2">
1121<hr>
1122<h3 class="SECT2"><a name="ADDCHCLASS" id="ADDCHCLASS">6.1. addch()
1123class of functions</a></h3>
1124<p>These functions put a single character into the current cursor
1125location and advance the position of the cursor. You can give the
1126character to be printed but they usually are used to print a
1127character with some attributes. Attributes are explained in detail
1128in later <a href="#ATTRIB">sections</a> of the document. If a
1129character is associated with an attribute(bold, reverse video
1130etc.), when curses prints the character, it is printed in that
1131attribute.</p>
1132<p>In order to combine a character with some attributes, you have
1133two options:</p>
1134<ul>
1135<li>
1136<p>By OR'ing a single character with the desired attribute macros.
1137These attribute macros could be found in the header file
1138<var class="LITERAL">ncurses.h</var>. For example, you want to
1139print a character ch(of type char) bold and underlined, you would
1140call addch() as below.</p>
1141<table border="0" bgcolor="#E0E0E0" width="90%">
1142<tr>
1143<td>
1144<pre class="PROGRAMLISTING">
1145<font color="#000000"> addch(ch | A_BOLD | A_UNDERLINE);</font>
1146</pre></td>
1147</tr>
1148</table>
1149</li>
1150<li>
1151<p>By using functions like <var class=
1152"LITERAL">attrset(),attron(),attroff()</var>. These functions are
1153explained in the <a href="#ATTRIB">Attributes</a> section. Briefly,
1154they manipulate the current attributes of the given window. Once
1155set, the character printed in the window are associated with the
1156attributes until it is turned off.</p>
1157</li>
1158</ul>
1159<p>Additionally, <var class="LITERAL">curses</var> provides some
1160special characters for character-based graphics. You can draw
1161tables, horizontal or vertical lines, etc. You can find all
1162avaliable characters in the header file <var class=
1163"LITERAL">ncurses.h</var>. Try looking for macros beginning with
1164<var class="LITERAL">ACS_</var> in this file.</p>
1165</div>
1166<div class="SECT2">
1167<hr>
1168<h3 class="SECT2"><a name="AEN298" id="AEN298">6.2. mvaddch(),
1169waddch() and mvwaddch()</a></h3>
1170<p><var class="LITERAL">mvaddch()</var> is used to move the cursor
1171to a given point, and then print. Thus, the calls:</p>
1172<table border="0" bgcolor="#E0E0E0" width="100%">
1173<tr>
1174<td>
1175<pre class="PROGRAMLISTING">
1176<font color=
1177"#000000"> move(row,col); /* moves the cursor to row<em>th</em> row and col<em>th</em> column */
1178 addch(ch);</font>
1179</pre></td>
1180</tr>
1181</table>
1182can be replaced by
1183<table border="0" bgcolor="#E0E0E0" width="100%">
1184<tr>
1185<td>
1186<pre class="PROGRAMLISTING">
1187<font color="#000000"> mvaddch(row,col,ch);</font>
1188</pre></td>
1189</tr>
1190</table>
1191<p><var class="LITERAL">waddch()</var> is similar to <var class=
1192"LITERAL">addch()</var>, except that it adds a character into the
1193given window. (Note that <var class="LITERAL">addch()</var> adds a
1194character into the window <var class="LITERAL">stdscr</var>.)</p>
1195<p>In a similar fashion <var class="LITERAL">mvwaddch()</var>
1196function is used to add a character into the given window at the
1197given coordinates.</p>
1198<p>Now, we are familiar with the basic output function <var class=
1199"LITERAL">addch()</var>. But, if we want to print a string, it
1200would be very annoying to print it character by character.
1201Fortunately, <var class="LITERAL">ncurses</var> provides
1202<var class="LITERAL">printf</var><em>-like</em> or <var class=
1203"LITERAL">puts</var><em>-like</em> functions.</p>
1204</div>
1205<div class="SECT2">
1206<hr>
1207<h3 class="SECT2"><a name="PRINTWCLASS" id="PRINTWCLASS">6.3.
1208printw() class of functions</a></h3>
1209<p>These functions are similar to <var class=
1210"LITERAL">printf()</var> with the added capability of printing at
1211any position on the screen.</p>
1212<div class="SECT3">
1213<hr>
1214<h4 class="SECT3"><a name="PRINTWMVPRINTW" id=
1215"PRINTWMVPRINTW">6.3.1. printw() and mvprintw</a></h4>
1216<p>These two functions work much like <var class=
1217"LITERAL">printf()</var>. <var class="LITERAL">mvprintw()</var> can
1218be used to move the cursor to a position and then print. If you
1219want to move the cursor first and then print using <var class=
1220"LITERAL">printw()</var> function, use <var class=
1221"LITERAL">move()</var> first and then use <var class=
1222"LITERAL">printw()</var> though I see no point why one should avoid
1223using <var class="LITERAL">mvprintw()</var>, you have the
1224flexibility to manipulate.</p>
1225</div>
1226<div class="SECT3">
1227<hr>
1228<h4 class="SECT3"><a name="WPRINTWMVWPRINTW" id=
1229"WPRINTWMVWPRINTW">6.3.2. wprintw() and mvwprintw</a></h4>
1230<p>These two functions are similar to above two except that they
1231print in the corresponding window given as argument.</p>
1232</div>
1233<div class="SECT3">
1234<hr>
1235<h4 class="SECT3"><a name="VWPRINTW" id="VWPRINTW">6.3.3.
1236vwprintw()</a></h4>
1237<p>This function is similar to <var class=
1238"LITERAL">vprintf()</var>. This can be used when variable number of
1239arguments are to be printed.</p>
1240</div>
1241<div class="SECT3">
1242<hr>
1243<h4 class="SECT3"><a name="SIMPLEPRINTWEX" id=
1244"SIMPLEPRINTWEX">6.3.4. A Simple printw example</a></h4>
1245<div class="EXAMPLE"><a name="BPREX" id="BPREX"></a>
1246<p><b>Example 3. A Simple printw example</b></p>
1247<table border="0" bgcolor="#E0E0E0" width="100%">
1248<tr>
1249<td>
1250<pre class="PROGRAMLISTING">
1251<font color="#000000"><span class=
1252"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt; /* ncurses.h includes stdio.h */
1253#include &lt;string.h&gt;
1254
1255int main()
1256{
1257 char mesg[]="Just a string"; /* message to be appeared on the screen */
1258 int row,col; /* to store the number of rows and *
1259 * the number of colums of the screen */
1260 initscr(); /* start the curses mode */
1261 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1262 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1263 /* print the message at the center of the screen */
1264 mvprintw(row-2,0,"This screen has %d rows and %d columns\n",row,col);
1265 printw("Try resizing your window(if possible) and then run this program again");
1266 refresh();
1267 getch();
1268 endwin();
1269
1270 return 0;
1271}</span></font>
1272</pre></td>
1273</tr>
1274</table>
1275</div>
1276<p>Above program demonstrates how easy it is to use <var class=
1277"LITERAL">printw</var>. You just feed the coordinates and the
1278message to be appeared on the screen, then it does what you
1279want.</p>
1280<p>The above program introduces us to a new function <var class=
1281"LITERAL">getmaxyx()</var>, a macro defined in <var class=
1282"LITERAL">ncurses.h</var>. It gives the number of columns and the
1283number of rows in a given window. <var class=
1284"LITERAL">getmaxyx()</var> does this by updating the variables
1285given to it. Since <var class="LITERAL">getmaxyx()</var> is not a
1286function we don't pass pointers to it, we just give two integer
1287variables.</p>
1288</div>
1289</div>
1290<div class="SECT2">
1291<hr>
1292<h3 class="SECT2"><a name="ADDSTRCLASS" id="ADDSTRCLASS">6.4.
1293addstr() class of functions</a></h3>
1294<p><var class="LITERAL">addstr()</var> is used to put a character
1295string into a given window. This function is similar to calling
1296<var class="LITERAL">addch()</var> once for each character in a
1297given string. This is true for all output functions. There are
1298other functions from this family such as <var class=
1299"LITERAL">mvaddstr(),mvwaddstr()</var> and <var class=
1300"LITERAL">waddstr()</var>, which obey the naming convention of
1301curses.(e.g. mvaddstr() is similar to the respective calls move()
1302and then addstr().) Another function of this family is addnstr(),
1303which takes an integer parameter(say n) additionally. This function
1304puts at most n characters into the screen. If n is negative, then
1305the entire string will be added.</p>
1306</div>
1307<div class="SECT2">
1308<hr>
1309<h3 class="SECT2"><a name="ACAUTION" id="ACAUTION">6.5. A word of
1310caution</a></h3>
1311<p>All these functions take y co-ordinate first and then x in their
1312arguments. A common mistake by beginners is to pass x,y in that
1313order. If you are doing too many manipulations of (y,x)
1314co-ordinates, think of dividing the screen into windows and
1315manipulate each one separately. Windows are explained in the
1316<a href="#WINDOWS">windows</a> section.</p>
1317</div>
1318</div>
1319<div class="SECT1">
1320<hr>
1321<h2 class="SECT1"><a name="SCANW" id="SCANW">7. Input
1322functions</a></h2>
1323<p>Well, printing without taking input, is boring. Let's see
1324functions which allow us to get input from user. These functions
1325also can be divided into three categories.</p>
1326<ol type="1">
1327<li>
1328<p>getch() class: Get a character</p>
1329</li>
1330<li>
1331<p>scanw() class: Get formatted input</p>
1332</li>
1333<li>
1334<p>getstr() class: Get strings</p>
1335</li>
1336</ol>
1337<div class="SECT2">
1338<hr>
1339<h3 class="SECT2"><a name="GETCHCLASS" id="GETCHCLASS">7.1. getch()
1340class of functions</a></h3>
1341<p>These functions read a single character from the terminal. But
1342there are several subtle facts to consider. For example if you
1343don't use the function cbreak(), curses will not read your input
1344characters contiguously but will begin read them only after a new
1345line or an EOF is encountered. In order to avoid this, the cbreak()
1346function must used so that characters are immediately available to
1347your program. Another widely used function is noecho(). As the name
1348suggests, when this function is set (used), the characters that are
1349keyed in by the user will not show up on the screen. The two
1350functions cbreak() and noecho() are typical examples of key
1351management. Functions of this genre are explained in the <a href=
1352"#KEYS">key management section</a> .</p>
1353</div>
1354<div class="SECT2">
1355<hr>
1356<h3 class="SECT2"><a name="SCANWCLASS" id="SCANWCLASS">7.2. scanw()
1357class of functions</a></h3>
1358<p>These functions are similar to <var class=
1359"LITERAL">scanf()</var> with the added capability of getting the
1360input from any location on the screen.</p>
1361<div class="SECT3">
1362<hr>
1363<h4 class="SECT3"><a name="SCANWMVSCANW" id="SCANWMVSCANW">7.2.1.
1364scanw() and mvscanw</a></h4>
1365<p>The usage of these functions is similar to that of <var class=
1366"LITERAL">sscanf()</var>, where the line to be scanned is provided
1367by <var class="LITERAL">wgetstr()</var> function. That is, these
1368functions call to <var class="LITERAL">wgetstr()</var>
1369function(explained below) and uses the resulting line for a
1370scan.</p>
1371</div>
1372<div class="SECT3">
1373<hr>
1374<h4 class="SECT3"><a name="WSCANWMVWSCANW" id=
1375"WSCANWMVWSCANW">7.2.2. wscanw() and mvwscanw()</a></h4>
1376<p>These are similar to above two functions except that they read
1377from a window, which is supplied as one of the arguments to these
1378functions.</p>
1379</div>
1380<div class="SECT3">
1381<hr>
1382<h4 class="SECT3"><a name="VWSCANW" id="VWSCANW">7.2.3.
1383vwscanw()</a></h4>
1384<p>This function is similar to <var class="LITERAL">vscanf()</var>.
1385This can be used when a variable number of arguments are to be
1386scanned.</p>
1387</div>
1388</div>
1389<div class="SECT2">
1390<hr>
1391<h3 class="SECT2"><a name="GETSTRCLASS" id="GETSTRCLASS">7.3.
1392getstr() class of functions</a></h3>
1393<p>These functions are used to get strings from the terminal. In
1394essence, this function performs the same task as would be achieved
1395by a series of calls to <var class="LITERAL">getch()</var> until a
1396newline, carriage return, or end-of-file is received. The resulting
1397string of characters are pointed to by <var class=
1398"LITERAL">str</var>, which is a character pointer provided by the
1399user.</p>
1400</div>
1401<div class="SECT2">
1402<hr>
1403<h3 class="SECT2"><a name="GETSTREX" id="GETSTREX">7.4. Some
1404examples</a></h3>
1405<div class="EXAMPLE"><a name="BSCEX" id="BSCEX"></a>
1406<p><b>Example 4. A Simple scanw example</b></p>
1407<table border="0" bgcolor="#E0E0E0" width="100%">
1408<tr>
1409<td>
1410<pre class="PROGRAMLISTING">
1411<font color="#000000"><span class=
1412"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt; /* ncurses.h includes stdio.h */
1413#include &lt;string.h&gt;
1414
1415int main()
1416{
1417 char mesg[]="Enter a string: "; /* message to be appeared on the screen */
1418 char str[80];
1419 int row,col; /* to store the number of rows and *
1420 * the number of colums of the screen */
1421 initscr(); /* start the curses mode */
1422 getmaxyx(stdscr,row,col); /* get the number of rows and columns */
1423 mvprintw(row/2,(col-strlen(mesg))/2,"%s",mesg);
1424 /* print the message at the center of the screen */
1425 getstr(str);
1426 mvprintw(LINES - 2, 0, "You Entered: %s", str);
1427 getch();
1428 endwin();
1429
1430 return 0;
1431}</span></font>
1432</pre></td>
1433</tr>
1434</table>
1435</div>
1436</div>
1437</div>
1438<div class="SECT1">
1439<hr>
1440<h2 class="SECT1"><a name="ATTRIB" id="ATTRIB">8.
1441Attributes</a></h2>
1442<p>We have seen an example of how attributes can be used to print
1443characters with some special effects. Attributes, when set
1444prudently, can present information in an easy, understandable
1445manner. The following program takes a C file as input and prints
1446the file with comments in bold. Scan through the code.</p>
1447<div class="EXAMPLE"><a name="BSIAT" id="BSIAT"></a>
1448<p><b>Example 5. A Simple Attributes example</b></p>
1449<table border="0" bgcolor="#E0E0E0" width="100%">
1450<tr>
1451<td>
1452<pre class="PROGRAMLISTING">
1453<font color="#000000"><span class=
1454"INLINEMEDIAOBJECT">/* pager functionality by Joseph Spainhour" &lt;spainhou@bellsouth.net&gt; */
1455#include &lt;ncurses.h&gt;
1456#include &lt;stdlib.h&gt;
1457
1458int main(int argc, char *argv[])
1459{
1460 int ch, prev, row, col;
1461 prev = EOF;
1462 FILE *fp;
1463 int y, x;
1464
1465 if(argc != 2)
1466 {
1467 printf("Usage: %s &lt;a c file name&gt;\n", argv[0]);
1468 exit(1);
1469 }
1470 fp = fopen(argv[1], "r");
1471 if(fp == NULL)
1472 {
1473 perror("Cannot open input file");
1474 exit(1);
1475 }
1476 initscr(); /* Start curses mode */
1477 getmaxyx(stdscr, row, col); /* find the boundaries of the screeen */
1478 while((ch = fgetc(fp)) != EOF) /* read the file till we reach the end */
1479 {
1480 getyx(stdscr, y, x); /* get the current curser position */
1481 if(y == (row - 1)) /* are we are at the end of the screen */
1482 {
1483 printw("&lt;-Press Any Key-&gt;"); /* tell the user to press a key */
1484 getch();
1485 clear(); /* clear the screen */
1486 move(0, 0); /* start at the beginning of the screen */
1487 }
1488 if(prev == '/' &amp;&amp; ch == '*') /* If it is / and * then only
1489 * switch bold on */
1490 {
1491 attron(A_BOLD); /* cut bold on */
1492 getyx(stdscr, y, x); /* get the current curser position */
1493 move(y, x - 1); /* back up one space */
1494 printw("%c%c", '/', ch); /* The actual printing is done here */
1495 }
1496 else
1497 printw("%c", ch);
1498 refresh();
1499 if(prev == '*' &amp;&amp; ch == '/')
1500 attroff(A_BOLD); /* Switch it off once we got *
1501 * and then / */
1502 prev = ch;
1503 }
1504 endwin(); /* End curses mode */
1505 fclose(fp);
1506 return 0;
1507}</span></font>
1508</pre></td>
1509</tr>
1510</table>
1511</div>
1512<p>Don't worry about all those initialization and other crap.
1513Concentrate on the while loop. It reads each character in the file
1514and searches for the pattern /*. Once it spots the pattern, it
1515switches the BOLD attribute on with <var class=
1516"LITERAL">attron()</var> . When we get the pattern */ it is
1517switched off by <var class="LITERAL">attroff()</var> .</p>
1518<p>The above program also introduces us to two useful functions
1519<var class="LITERAL">getyx()</var> and <var class=
1520"LITERAL">move()</var>. The first function gets the co-ordinates of
1521the present cursor into the variables y, x. Since getyx() is a
1522macro we don't have to pass pointers to variables. The function
1523<var class="LITERAL">move()</var> moves the cursor to the
1524co-ordinates given to it.</p>
1525<p>The above program is really a simple one which doesn't do much.
1526On these lines one could write a more useful program which reads a
1527C file, parses it and prints it in different colors. One could even
1528extend it to other languages as well.</p>
1529<div class="SECT2">
1530<hr>
1531<h3 class="SECT2"><a name="ATTRIBDETAILS" id="ATTRIBDETAILS">8.1.
1532The details</a></h3>
1533<p>Let's get into more details of attributes. The functions
1534<var class="LITERAL">attron(), attroff(), attrset()</var> , and
1535their sister functions <var class="LITERAL">attr_get()</var> etc..
1536can be used to switch attributes on/off , get attributes and
1537produce a colorful display.</p>
1538<p>The functions attron and attroff take a bit-mask of attributes
1539and switch them on or off, respectively. The following video
1540attributes, which are defined in &lt;curses.h&gt; can be passed to
1541these functions.</p>
1542<table border="0" bgcolor="#E0E0E0" width="100%">
1543<tr>
1544<td>
1545<pre class="PROGRAMLISTING">
1546<font color="#000000">
1547 A_NORMAL Normal display (no highlight)
1548 A_STANDOUT Best highlighting mode of the terminal.
1549 A_UNDERLINE Underlining
1550 A_REVERSE Reverse video
1551 A_BLINK Blinking
1552 A_DIM Half bright
1553 A_BOLD Extra bright or bold
1554 A_PROTECT Protected mode
1555 A_INVIS Invisible or blank mode
1556 A_ALTCHARSET Alternate character set
1557 A_CHARTEXT Bit-mask to extract a character
1558 COLOR_PAIR(n) Color-pair number n
1559 </font>
1560</pre></td>
1561</tr>
1562</table>
1563<p>The last one is the most colorful one :-) Colors are explained
1564in the <a href="#color" target="_top">next sections</a>.</p>
1565<p>We can OR(|) any number of above attributes to get a combined
1566effect. If you wanted reverse video with blinking characters you
1567can use</p>
1568<table border="0" bgcolor="#E0E0E0" width="100%">
1569<tr>
1570<td>
1571<pre class="PROGRAMLISTING">
1572<font color="#000000"> attron(A_REVERSE | A_BLINK);</font>
1573</pre></td>
1574</tr>
1575</table>
1576</div>
1577<div class="SECT2">
1578<hr>
1579<h3 class="SECT2"><a name="ATTRONVSATTRSET" id=
1580"ATTRONVSATTRSET">8.2. attron() vs attrset()</a></h3>
1581<p>Then what is the difference between attron() and attrset()?
1582attrset sets the attributes of window whereas attron just switches
1583on the attribute given to it. So attrset() fully overrides whatever
1584attributes the window previously had and sets it to the new
1585attribute(s). Similarly attroff() just switches off the
1586attribute(s) given to it as an argument. This gives us the
1587flexibility of managing attributes easily.But if you use them
1588carelessly you may loose track of what attributes the window has
1589and garble the display. This is especially true while managing
1590menus with colors and highlighting. So decide on a consistent
1591policy and stick to it. You can always use <var class=
1592"LITERAL">standend()</var> which is equivalent to <var class=
1593"LITERAL">attrset(A_NORMAL)</var> which turns off all attributes
1594and brings you to normal mode.</p>
1595</div>
1596<div class="SECT2">
1597<hr>
1598<h3 class="SECT2"><a name="ATTR_GET" id="ATTR_GET">8.3.
1599attr_get()</a></h3>
1600<p>The function attr_get() gets the current attributes and color
1601pair of the window. Though we might not use this as often as the
1602above functions, this is useful in scanning areas of screen. Say we
1603wanted to do some complex update on screen and we are not sure what
1604attribute each character is associated with. Then this function can
1605be used with either attrset or attron to produce the desired
1606effect.</p>
1607</div>
1608<div class="SECT2">
1609<hr>
1610<h3 class="SECT2"><a name="ATTR_FUNCS" id="ATTR_FUNCS">8.4. attr_
1611functions</a></h3>
1612<p>There are series of functions like attr_set(), attr_on etc..
1613These are similar to above functions except that they take
1614parameters of type <var class="LITERAL">attr_t</var>.</p>
1615</div>
1616<div class="SECT2">
1617<hr>
1618<h3 class="SECT2"><a name="WATTRFUNCS" id="WATTRFUNCS">8.5. wattr
1619functions</a></h3>
1620<p>For each of the above functions we have a corresponding function
1621with 'w' which operates on a particular window. The above functions
1622operate on stdscr.</p>
1623</div>
1624<div class="SECT2">
1625<hr>
1626<h3 class="SECT2"><a name="CHGAT" id="CHGAT">8.6. chgat()
1627functions</a></h3>
1628<p>The function chgat() is listed in the end of the man page
1629curs_attr. It actually is a useful one. This function can be used
1630to set attributes for a group of characters without moving. I mean
1631it !!! without moving the cursor :-) It changes the attributes of a
1632given number of characters starting at the current cursor
1633location.</p>
1634<p>We can give -1 as the character count to update till end of
1635line. If you want to change attributes of characters from current
1636position to end of line, just use this.</p>
1637<table border="0" bgcolor="#E0E0E0" width="100%">
1638<tr>
1639<td>
1640<pre class="PROGRAMLISTING">
1641<font color="#000000"> chgat(-1, A_REVERSE, 0, NULL);</font>
1642</pre></td>
1643</tr>
1644</table>
1645<p>This function is useful when changing attributes for characters
1646that are already on the screen. Move to the character from which
1647you want to change and change the attribute.</p>
1648<p>Other functions wchgat(), mvchgat(), wchgat() behave similarly
1649except that the w functions operate on the particular window. The
1650mv functions first move the cursor then perform the work given to
1651them. Actually chgat is a macro which is replaced by a wchgat()
1652with stdscr as the window. Most of the "w-less" functions are
1653macros.</p>
1654<div class="EXAMPLE"><a name="BWICH" id="BWICH"></a>
1655<p><b>Example 6. Chgat() Usage example</b></p>
1656<table border="0" bgcolor="#E0E0E0" width="100%">
1657<tr>
1658<td>
1659<pre class="PROGRAMLISTING">
1660<font color="#000000"><span class=
1661"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
1662
1663int main(int argc, char *argv[])
1664{ initscr(); /* Start curses mode */
1665 start_color(); /* Start color functionality */
1666
1667 init_pair(1, COLOR_CYAN, COLOR_BLACK);
1668 printw("A Big string which i didn't care to type fully ");
1669 mvchgat(0, 0, -1, A_BLINK, 1, NULL);
1670 /*
1671 * First two parameters specify the position at which to start
1672 * Third parameter number of characters to update. -1 means till
1673 * end of line
1674 * Forth parameter is the normal attribute you wanted to give
1675 * to the charcter
1676 * Fifth is the color index. It is the index given during init_pair()
1677 * use 0 if you didn't want color
1678 * Sixth one is always NULL
1679 */
1680 refresh();
1681 getch();
1682 endwin(); /* End curses mode */
1683 return 0;
1684}</span></font>
1685</pre></td>
1686</tr>
1687</table>
1688</div>
1689<p>This example also introduces us to the color world of curses.
1690Colors will be explained in detail later. Use 0 for no color.</p>
1691</div>
1692</div>
1693<div class="SECT1">
1694<hr>
1695<h2 class="SECT1"><a name="WINDOWS" id="WINDOWS">9.
1696Windows</a></h2>
1697<p>Windows form the most important concept in curses. You have seen
1698the standard window stdscr above where all the functions implicitly
1699operated on this window. Now to make design even a simplest GUI,
1700you need to resort to windows. The main reason you may want to use
1701windows is to manipulate parts of the screen separately, for better
1702efficiency, by updating only the windows that need to be changed
1703and for a better design. I would say the last reason is the most
1704important in going for windows. You should always strive for a
1705better and easy-to-manage design in your programs. If you are
1706writing big, complex GUIs this is of pivotal importance before you
1707start doing anything.</p>
1708<div class="SECT2">
1709<hr>
1710<h3 class="SECT2"><a name="WINDOWBASICS" id="WINDOWBASICS">9.1. The
1711basics</a></h3>
1712<p>A Window can be created by calling the function <var class=
1713"LITERAL">newwin()</var>. It doesn't create any thing on the screen
1714actually. It allocates memory for a structure to manipulate the
1715window and updates the structure with data regarding the window
1716like it's size, beginy, beginx etc.. Hence in curses, a window is
1717just an abstraction of an imaginary window, which can be
1718manipulated independent of other parts of screen. The function
1719newwin() returns a pointer to structure WINDOW, which can be passed
1720to window related functions like wprintw() etc.. Finally the window
1721can be destroyed with delwin(). It will deallocate the memory
1722associated with the window structure.</p>
1723</div>
1724<div class="SECT2">
1725<hr>
1726<h3 class="SECT2"><a name="LETBEWINDOW" id="LETBEWINDOW">9.2. Let
1727there be a Window !!!</a></h3>
1728<p>What fun is it, if a window is created and we can't see it. So
1729the fun part begins by displaying the window. The function
1730<var class="LITERAL">box()</var> can be used to draw a border
1731around the window. Let's explore these functions in more detail in
1732this example.</p>
1733<div class="EXAMPLE"><a name="BWIBO" id="BWIBO"></a>
1734<p><b>Example 7. Window Border example</b></p>
1735<table border="0" bgcolor="#E0E0E0" width="100%">
1736<tr>
1737<td>
1738<pre class="PROGRAMLISTING">
1739<font color="#000000"><span class=
1740"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
1741
1742
1743WINDOW *create_newwin(int height, int width, int starty, int startx);
1744void destroy_win(WINDOW *local_win);
1745
1746int main(int argc, char *argv[])
1747{ WINDOW *my_win;
1748 int startx, starty, width, height;
1749 int ch;
1750
1751 initscr(); /* Start curses mode */
1752 cbreak(); /* Line buffering disabled, Pass on
1753 * everty thing to me */
1754 keypad(stdscr, TRUE); /* I need that nifty F1 */
1755
1756 height = 3;
1757 width = 10;
1758 starty = (LINES - height) / 2; /* Calculating for a center placement */
1759 startx = (COLS - width) / 2; /* of the window */
1760 printw("Press F1 to exit");
1761 refresh();
1762 my_win = create_newwin(height, width, starty, startx);
1763
1764 while((ch = getch()) != KEY_F(1))
1765 { switch(ch)
1766 { case KEY_LEFT:
1767 destroy_win(my_win);
1768 my_win = create_newwin(height, width, starty,--startx);
1769 break;
1770 case KEY_RIGHT:
1771 destroy_win(my_win);
1772 my_win = create_newwin(height, width, starty,++startx);
1773 break;
1774 case KEY_UP:
1775 destroy_win(my_win);
1776 my_win = create_newwin(height, width, --starty,startx);
1777 break;
1778 case KEY_DOWN:
1779 destroy_win(my_win);
1780 my_win = create_newwin(height, width, ++starty,startx);
1781 break;
1782 }
1783 }
1784
1785 endwin(); /* End curses mode */
1786 return 0;
1787}
1788
1789WINDOW *create_newwin(int height, int width, int starty, int startx)
1790{ WINDOW *local_win;
1791
1792 local_win = newwin(height, width, starty, startx);
1793 box(local_win, 0 , 0); /* 0, 0 gives default characters
1794 * for the vertical and horizontal
1795 * lines */
1796 wrefresh(local_win); /* Show that box */
1797
1798 return local_win;
1799}
1800
1801void destroy_win(WINDOW *local_win)
1802{
1803 /* box(local_win, ' ', ' '); : This won't produce the desired
1804 * result of erasing the window. It will leave it's four corners
1805 * and so an ugly remnant of window.
1806 */
1807 wborder(local_win, ' ', ' ', ' ',' ',' ',' ',' ',' ');
1808 /* The parameters taken are
1809 * 1. win: the window on which to operate
1810 * 2. ls: character to be used for the left side of the window
1811 * 3. rs: character to be used for the right side of the window
1812 * 4. ts: character to be used for the top side of the window
1813 * 5. bs: character to be used for the bottom side of the window
1814 * 6. tl: character to be used for the top left corner of the window
1815 * 7. tr: character to be used for the top right corner of the window
1816 * 8. bl: character to be used for the bottom left corner of the window
1817 * 9. br: character to be used for the bottom right corner of the window
1818 */
1819 wrefresh(local_win);
1820 delwin(local_win);
1821}</span></font>
1822</pre></td>
1823</tr>
1824</table>
1825</div>
1826</div>
1827<div class="SECT2">
1828<hr>
1829<h3 class="SECT2"><a name="BORDEREXEXPL" id="BORDEREXEXPL">9.3.
1830Explanation</a></h3>
1831<p>Don't scream. I know it's a big example. But I have to explain
1832some important things here :-). This program creates a rectangular
1833window that can be moved with left, right, up, down arrow keys. It
1834repeatedly creates and destroys windows as user press a key. Don't
1835go beyond the screen limits. Checking for those limits is left as
1836an exercise for the reader. Let's dissect it by line by line.</p>
1837<p>The <var class="LITERAL">create_newwin()</var> function creates
1838a window with <var class="LITERAL">newwin()</var> and displays a
1839border around it with box. The function <var class=
1840"LITERAL">destroy_win()</var> first erases the window from screen
1841by painting a border with ' ' character and then calling
1842<var class="LITERAL">delwin()</var> to deallocate memory related to
1843it. Depending on the key the user presses, starty or startx is
1844changed and a new window is created.</p>
1845<p>In the destroy_win, as you can see, I used wborder instead of
1846box. The reason is written in the comments (You missed it. I know.
1847Read the code :-)). wborder draws a border around the window with
1848the characters given to it as the 4 corner points and the 4 lines.
1849To put it clearly, if you have called wborder as below:</p>
1850<table border="0" bgcolor="#E0E0E0" width="100%">
1851<tr>
1852<td>
1853<pre class="PROGRAMLISTING">
1854<font color=
1855"#000000"> wborder(win, '|', '|', '-', '-', '+', '+', '+', '+');</font>
1856</pre></td>
1857</tr>
1858</table>
1859<p>it produces some thing like</p>
1860<table border="0" bgcolor="#E0E0E0" width="100%">
1861<tr>
1862<td>
1863<pre class="PROGRAMLISTING">
1864<font color="#000000"> +------------+
1865 | |
1866 | |
1867 | |
1868 | |
1869 | |
1870 | |
1871 +------------+</font>
1872</pre></td>
1873</tr>
1874</table>
1875</div>
1876<div class="SECT2">
1877<hr>
1878<h3 class="SECT2"><a name="OTHERSTUFF" id="OTHERSTUFF">9.4. The
1879other stuff in the example</a></h3>
1880<p>You can also see in the above examples, that I have used the
1881variables COLS, LINES which are initialized to the screen sizes
1882after initscr(). They can be useful in finding screen dimensions
1883and finding the center co-ordinate of the screen as above. The
1884function <var class="LITERAL">getch()</var> as usual gets the key
1885from keyboard and according to the key it does the corresponding
1886work. This type of switch- case is very common in any GUI based
1887programs.</p>
1888</div>
1889<div class="SECT2">
1890<hr>
1891<h3 class="SECT2"><a name="OTHERBORDERFUNCS" id=
1892"OTHERBORDERFUNCS">9.5. Other Border functions</a></h3>
1893<p>Above program is grossly inefficient in that with each press of
1894a key, a window is destroyed and another is created. So let's write
1895a more efficient program which uses other border related
1896functions.</p>
1897<p>The following program uses <var class="LITERAL">mvhline()</var>
1898and <var class="LITERAL">mvvline()</var> to achieve similar effect.
1899These two functions are simple. They create a horizontal or
1900vertical line of the specified length at the specified
1901position.</p>
1902<div class="EXAMPLE"><a name="BOTBO" id="BOTBO"></a>
1903<p><b>Example 8. More border functions</b></p>
1904<table border="0" bgcolor="#E0E0E0" width="100%">
1905<tr>
1906<td>
1907<pre class="PROGRAMLISTING">
1908<font color="#000000"><span class=
1909"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
1910
1911typedef struct _win_border_struct {
1912 chtype ls, rs, ts, bs,
1913 tl, tr, bl, br;
1914}WIN_BORDER;
1915
1916typedef struct _WIN_struct {
1917
1918 int startx, starty;
1919 int height, width;
1920 WIN_BORDER border;
1921}WIN;
1922
1923void init_win_params(WIN *p_win);
1924void print_win_params(WIN *p_win);
1925void create_box(WIN *win, bool flag);
1926
1927int main(int argc, char *argv[])
1928{ WIN win;
1929 int ch;
1930
1931 initscr(); /* Start curses mode */
1932 start_color(); /* Start the color functionality */
1933 cbreak(); /* Line buffering disabled, Pass on
1934 * everty thing to me */
1935 keypad(stdscr, TRUE); /* I need that nifty F1 */
1936 noecho();
1937 init_pair(1, COLOR_CYAN, COLOR_BLACK);
1938
1939 /* Initialize the window parameters */
1940 init_win_params(&amp;win);
1941 print_win_params(&amp;win);
1942
1943 attron(COLOR_PAIR(1));
1944 printw("Press F1 to exit");
1945 refresh();
1946 attroff(COLOR_PAIR(1));
1947
1948 create_box(&amp;win, TRUE);
1949 while((ch = getch()) != KEY_F(1))
1950 { switch(ch)
1951 { case KEY_LEFT:
1952 create_box(&amp;win, FALSE);
1953 --win.startx;
1954 create_box(&amp;win, TRUE);
1955 break;
1956 case KEY_RIGHT:
1957 create_box(&amp;win, FALSE);
1958 ++win.startx;
1959 create_box(&amp;win, TRUE);
1960 break;
1961 case KEY_UP:
1962 create_box(&amp;win, FALSE);
1963 --win.starty;
1964 create_box(&amp;win, TRUE);
1965 break;
1966 case KEY_DOWN:
1967 create_box(&amp;win, FALSE);
1968 ++win.starty;
1969 create_box(&amp;win, TRUE);
1970 break;
1971 }
1972 }
1973 endwin(); /* End curses mode */
1974 return 0;
1975}
1976void init_win_params(WIN *p_win)
1977{
1978 p_win-&gt;height = 3;
1979 p_win-&gt;width = 10;
1980 p_win-&gt;starty = (LINES - p_win-&gt;height)/2;
1981 p_win-&gt;startx = (COLS - p_win-&gt;width)/2;
1982
1983 p_win-&gt;border.ls = '|';
1984 p_win-&gt;border.rs = '|';
1985 p_win-&gt;border.ts = '-';
1986 p_win-&gt;border.bs = '-';
1987 p_win-&gt;border.tl = '+';
1988 p_win-&gt;border.tr = '+';
1989 p_win-&gt;border.bl = '+';
1990 p_win-&gt;border.br = '+';
1991
1992}
1993void print_win_params(WIN *p_win)
1994{
1995#ifdef _DEBUG
1996 mvprintw(25, 0, "%d %d %d %d", p_win-&gt;startx, p_win-&gt;starty,
1997 p_win-&gt;width, p_win-&gt;height);
1998 refresh();
1999#endif
2000}
2001void create_box(WIN *p_win, bool flag)
2002{ int i, j;
2003 int x, y, w, h;
2004
2005 x = p_win-&gt;startx;
2006 y = p_win-&gt;starty;
2007 w = p_win-&gt;width;
2008 h = p_win-&gt;height;
2009
2010 if(flag == TRUE)
2011 { mvaddch(y, x, p_win-&gt;border.tl);
2012 mvaddch(y, x + w, p_win-&gt;border.tr);
2013 mvaddch(y + h, x, p_win-&gt;border.bl);
2014 mvaddch(y + h, x + w, p_win-&gt;border.br);
2015 mvhline(y, x + 1, p_win-&gt;border.ts, w - 1);
2016 mvhline(y + h, x + 1, p_win-&gt;border.bs, w - 1);
2017 mvvline(y + 1, x, p_win-&gt;border.ls, h - 1);
2018 mvvline(y + 1, x + w, p_win-&gt;border.rs, h - 1);
2019
2020 }
2021 else
2022 for(j = y; j &lt;= y + h; ++j)
2023 for(i = x; i &lt;= x + w; ++i)
2024 mvaddch(j, i, ' ');
2025
2026 refresh();
2027
2028}</span></font>
2029</pre></td>
2030</tr>
2031</table>
2032</div>
2033</div>
2034</div>
2035<div class="SECT1">
2036<hr>
2037<h2 class="SECT1"><a name="COLOR" id="COLOR">10. Colors</a></h2>
2038<div class="SECT2">
2039<h3 class="SECT2"><a name="COLORBASICS" id="COLORBASICS">10.1. The
2040basics</a></h3>
2041<p>Life seems dull with no colors. Curses has a nice mechanism to
2042handle colors. Let's get into the thick of the things with a small
2043program.</p>
2044<div class="EXAMPLE"><a name="BSICO" id="BSICO"></a>
2045<p><b>Example 9. A Simple Color example</b></p>
2046<table border="0" bgcolor="#E0E0E0" width="100%">
2047<tr>
2048<td>
2049<pre class="PROGRAMLISTING">
2050<font color="#000000"><span class=
2051"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
2052
2053void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string);
2054int main(int argc, char *argv[])
2055{ initscr(); /* Start curses mode */
2056 if(has_colors() == FALSE)
2057 { endwin();
2058 printf("Your terminal does not support color\n");
2059 exit(1);
2060 }
2061 start_color(); /* Start color */
2062 init_pair(1, COLOR_RED, COLOR_BLACK);
2063
2064 attron(COLOR_PAIR(1));
2065 print_in_middle(stdscr, LINES / 2, 0, 0, "Viola !!! In color ...");
2066 attroff(COLOR_PAIR(1));
2067 getch();
2068 endwin();
2069}
2070void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string)
2071{ int length, x, y;
2072 float temp;
2073
2074 if(win == NULL)
2075 win = stdscr;
2076 getyx(win, y, x);
2077 if(startx != 0)
2078 x = startx;
2079 if(starty != 0)
2080 y = starty;
2081 if(width == 0)
2082 width = 80;
2083
2084 length = strlen(string);
2085 temp = (width - length)/ 2;
2086 x = startx + (int)temp;
2087 mvwprintw(win, y, x, "%s", string);
2088 refresh();
2089}
2090</span></font>
2091</pre></td>
2092</tr>
2093</table>
2094</div>
2095<p>As you can see, to start using color, you should first call the
2096function <var class="LITERAL">start_color()</var>. After that, you
2097can use color capabilities of your terminals using various
2098functions. To find out whether a terminal has color capabilities or
2099not, you can use <var class="LITERAL">has_colors()</var> function,
2100which returns FALSE if the terminal does not support color.</p>
2101<p>Curses initializes all the colors supported by terminal when
2102start_color() is called. These can be accessed by the define
2103constants like <var class="LITERAL">COLOR_BLACK</var> etc. Now to
2104actually start using colors, you have to define pairs. Colors are
2105always used in pairs. That means you have to use the function
2106<var class="LITERAL">init_pair()</var> to define the foreground and
2107background for the pair number you give. After that that pair
2108number can be used as a normal attribute with <var class=
2109"LITERAL">COLOR_PAIR()</var>function. This may seem to be
2110cumbersome at first. But this elegant solution allows us to manage
2111color pairs very easily. To appreciate it, you have to look into
2112the the source code of "dialog", a utility for displaying dialog
2113boxes from shell scripts. The developers have defined foreground
2114and background combinations for all the colors they might need and
2115initialized at the beginning. This makes it very easy to set
2116attributes just by accessing a pair which we already have defined
2117as a constant.</p>
2118<p>The following colors are defined in <var class=
2119"LITERAL">curses.h</var>. You can use these as parameters for
2120various color functions.</p>
2121<table border="0" bgcolor="#E0E0E0" width="100%">
2122<tr>
2123<td>
2124<pre class="PROGRAMLISTING">
2125<font color="#000000"> COLOR_BLACK 0
2126 COLOR_RED 1
2127 COLOR_GREEN 2
2128 COLOR_YELLOW 3
2129 COLOR_BLUE 4
2130 COLOR_MAGENTA 5
2131 COLOR_CYAN 6
2132 COLOR_WHITE 7</font>
2133</pre></td>
2134</tr>
2135</table>
2136</div>
2137<div class="SECT2">
2138<hr>
2139<h3 class="SECT2"><a name="CHANGECOLORDEFS" id=
2140"CHANGECOLORDEFS">10.2. Changing Color Definitions</a></h3>
2141<p>The function <var class="LITERAL">init_color()</var>can be used
2142to change the rgb values for the colors defined by curses
2143initially. Say you wanted to lighten the intensity of red color by
2144a minuscule. Then you can use this function as</p>
2145<table border="0" bgcolor="#E0E0E0" width="100%">
2146<tr>
2147<td>
2148<pre class="PROGRAMLISTING">
2149<font color="#000000"> init_color(COLOR_RED, 700, 0, 0);
2150 /* param 1 : color name
2151 * param 2, 3, 4 : rgb content min = 0, max = 1000 */</font>
2152</pre></td>
2153</tr>
2154</table>
2155<p>If your terminal cannot change the color definitions, the
2156function returns ERR. The function <var class=
2157"LITERAL">can_change_color()</var> can be used to find out whether
2158the terminal has the capability of changing color content or not.
2159The rgb content is scaled from 0 to 1000. Initially RED color is
2160defined with content 1000(r), 0(g), 0(b).</p>
2161</div>
2162<div class="SECT2">
2163<hr>
2164<h3 class="SECT2"><a name="COLORCONTENT" id="COLORCONTENT">10.3.
2165Color Content</a></h3>
2166<p>The functions <var class="LITERAL">color_content()</var> and
2167<var class="LITERAL">pair_content()</var> can be used to find the
2168color content and foreground, background combination for the
2169pair.</p>
2170</div>
2171</div>
2172<div class="SECT1">
2173<hr>
2174<h2 class="SECT1"><a name="KEYS" id="KEYS">11. Interfacing with the
2175key board</a></h2>
2176<div class="SECT2">
2177<h3 class="SECT2"><a name="KEYSBASICS" id="KEYSBASICS">11.1. The
2178Basics</a></h3>
2179<p>No GUI is complete without a strong user interface and to
2180interact with the user, a curses program should be sensitive to key
2181presses or the mouse actions done by the user. Let's deal with the
2182keys first.</p>
2183<p>As you have seen in almost all of the above examples, it's very
2184easy to get key input from the user. A simple way of getting key
2185presses is to use <var class="LITERAL">getch()</var> function. The
2186cbreak mode should be enabled to read keys when you are interested
2187in reading individual key hits rather than complete lines of text
2188(which usually end with a carriage return). keypad should be
2189enabled to get the Functions keys, arrow keys etc. See the
2190initialization section for details.</p>
2191<p><var class="LITERAL">getch()</var> returns an integer
2192corresponding to the key pressed. If it is a normal character, the
2193integer value will be equivalent to the character. Otherwise it
2194returns a number which can be matched with the constants defined in
2195<var class="LITERAL">curses.h</var>. For example if the user
2196presses F1, the integer returned is 265. This can be checked using
2197the macro KEY_F() defined in curses.h. This makes reading keys
2198portable and easy to manage.</p>
2199<p>For example, if you call getch() like this</p>
2200<table border="0" bgcolor="#E0E0E0" width="100%">
2201<tr>
2202<td>
2203<pre class="PROGRAMLISTING">
2204<font color="#000000"> int ch;
2205
2206 ch = getch();</font>
2207</pre></td>
2208</tr>
2209</table>
2210<p>getch() will wait for the user to press a key, (unless you
2211specified a timeout) and when user presses a key, the corresponding
2212integer is returned. Then you can check the value returned with the
2213constants defined in curses.h to match against the keys you
2214want.</p>
2215<p>The following code piece will do that job.</p>
2216<table border="0" bgcolor="#E0E0E0" width="100%">
2217<tr>
2218<td>
2219<pre class="PROGRAMLISTING">
2220<font color="#000000"> if(ch == KEY_LEFT)
2221 printw("Left arrow is pressed\n");</font>
2222</pre></td>
2223</tr>
2224</table>
2225<p>Let's write a small program which creates a menu which can be
2226navigated by up and down arrows.</p>
2227</div>
2228<div class="SECT2">
2229<hr>
2230<h3 class="SECT2"><a name="SIMPLEKEYEX" id="SIMPLEKEYEX">11.2. A
2231Simple Key Usage example</a></h3>
2232<div class="EXAMPLE"><a name="BSIKE" id="BSIKE"></a>
2233<p><b>Example 10. A Simple Key Usage example</b></p>
2234<table border="0" bgcolor="#E0E0E0" width="100%">
2235<tr>
2236<td>
2237<pre class="PROGRAMLISTING">
2238<font color="#000000"><span class=
2239"INLINEMEDIAOBJECT">#include &lt;stdio.h&gt;
2240#include &lt;ncurses.h&gt;
2241
2242#define WIDTH 30
2243#define HEIGHT 10
2244
2245int startx = 0;
2246int starty = 0;
2247
2248char *choices[] = {
2249 "Choice 1",
2250 "Choice 2",
2251 "Choice 3",
2252 "Choice 4",
2253 "Exit",
2254 };
2255int n_choices = sizeof(choices) / sizeof(char *);
2256void print_menu(WINDOW *menu_win, int highlight);
2257
2258int main()
2259{ WINDOW *menu_win;
2260 int highlight = 1;
2261 int choice = 0;
2262 int c;
2263
2264 initscr();
2265 clear();
2266 noecho();
2267 cbreak(); /* Line buffering disabled. pass on everything */
2268 startx = (80 - WIDTH) / 2;
2269 starty = (24 - HEIGHT) / 2;
2270
2271 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2272 keypad(menu_win, TRUE);
2273 mvprintw(0, 0, "Use arrow keys to go up and down, Press enter to select a choice");
2274 refresh();
2275 print_menu(menu_win, highlight);
2276 while(1)
2277 { c = wgetch(menu_win);
2278 switch(c)
2279 { case KEY_UP:
2280 if(highlight == 1)
2281 highlight = n_choices;
2282 else
2283 --highlight;
2284 break;
2285 case KEY_DOWN:
2286 if(highlight == n_choices)
2287 highlight = 1;
2288 else
2289 ++highlight;
2290 break;
2291 case 10:
2292 choice = highlight;
2293 break;
2294 default:
2295 mvprintw(24, 0, "Charcter pressed is = %3d Hopefully it can be printed as '%c'", c, c);
2296 refresh();
2297 break;
2298 }
2299 print_menu(menu_win, highlight);
2300 if(choice != 0) /* User did a choice come out of the infinite loop */
2301 break;
2302 }
2303 mvprintw(23, 0, "You chose choice %d with choice string %s\n", choice, choices[choice - 1]);
2304 clrtoeol();
2305 refresh();
2306 endwin();
2307 return 0;
2308}
2309
2310
2311void print_menu(WINDOW *menu_win, int highlight)
2312{
2313 int x, y, i;
2314
2315 x = 2;
2316 y = 2;
2317 box(menu_win, 0, 0);
2318 for(i = 0; i &lt; n_choices; ++i)
2319 { if(highlight == i + 1) /* High light the present choice */
2320 { wattron(menu_win, A_REVERSE);
2321 mvwprintw(menu_win, y, x, "%s", choices[i]);
2322 wattroff(menu_win, A_REVERSE);
2323 }
2324 else
2325 mvwprintw(menu_win, y, x, "%s", choices[i]);
2326 ++y;
2327 }
2328 wrefresh(menu_win);
2329}
2330</span></font>
2331</pre></td>
2332</tr>
2333</table>
2334</div>
2335</div>
2336</div>
2337<div class="SECT1">
2338<hr>
2339<h2 class="SECT1"><a name="MOUSE" id="MOUSE">12. Interfacing with
2340the mouse</a></h2>
2341<p>Now that you have seen how to get keys, lets do the same thing
2342from mouse. Usually each UI allows the user to interact with both
2343keyboard and mouse.</p>
2344<div class="SECT2">
2345<hr>
2346<h3 class="SECT2"><a name="MOUSEBASICS" id="MOUSEBASICS">12.1. The
2347Basics</a></h3>
2348<p>Before you do any thing else, the events you want to receive
2349have to be enabled with <var class="LITERAL">mousemask()</var>.</p>
2350<table border="0" bgcolor="#E0E0E0" width="100%">
2351<tr>
2352<td>
2353<pre class="PROGRAMLISTING">
2354<font color=
2355"#000000"> mousemask( mmask_t newmask, /* The events you want to listen to */
2356 mmask_t *oldmask) /* The old events mask */</font>
2357</pre></td>
2358</tr>
2359</table>
2360<p>The first parameter to above function is a bit mask of events
2361you would like to listen. By default, all the events are turned
2362off. The bit mask <var class="LITERAL">ALL_MOUSE_EVENTS</var> can
2363be used to get all the events.</p>
2364<p>The following are all the event masks:</p>
2365<table border="0" bgcolor="#E0E0E0" width="100%">
2366<tr>
2367<td>
2368<pre class="PROGRAMLISTING">
2369<font color="#000000"> Name Description
2370 ---------------------------------------------------------------------
2371 BUTTON1_PRESSED mouse button 1 down
2372 BUTTON1_RELEASED mouse button 1 up
2373 BUTTON1_CLICKED mouse button 1 clicked
2374 BUTTON1_DOUBLE_CLICKED mouse button 1 double clicked
2375 BUTTON1_TRIPLE_CLICKED mouse button 1 triple clicked
2376 BUTTON2_PRESSED mouse button 2 down
2377 BUTTON2_RELEASED mouse button 2 up
2378 BUTTON2_CLICKED mouse button 2 clicked
2379 BUTTON2_DOUBLE_CLICKED mouse button 2 double clicked
2380 BUTTON2_TRIPLE_CLICKED mouse button 2 triple clicked
2381 BUTTON3_PRESSED mouse button 3 down
2382 BUTTON3_RELEASED mouse button 3 up
2383 BUTTON3_CLICKED mouse button 3 clicked
2384 BUTTON3_DOUBLE_CLICKED mouse button 3 double clicked
2385 BUTTON3_TRIPLE_CLICKED mouse button 3 triple clicked
2386 BUTTON4_PRESSED mouse button 4 down
2387 BUTTON4_RELEASED mouse button 4 up
2388 BUTTON4_CLICKED mouse button 4 clicked
2389 BUTTON4_DOUBLE_CLICKED mouse button 4 double clicked
2390 BUTTON4_TRIPLE_CLICKED mouse button 4 triple clicked
2391 BUTTON_SHIFT shift was down during button state change
2392 BUTTON_CTRL control was down during button state change
2393 BUTTON_ALT alt was down during button state change
2394 ALL_MOUSE_EVENTS report all button state changes
2395 REPORT_MOUSE_POSITION report mouse movement</font>
2396</pre></td>
2397</tr>
2398</table>
2399</div>
2400<div class="SECT2">
2401<hr>
2402<h3 class="SECT2"><a name="GETTINGEVENTS" id="GETTINGEVENTS">12.2.
2403Getting the events</a></h3>
2404<p>Once a class of mouse events have been enabled, getch() class of
2405functions return KEY_MOUSE every time some mouse event happens.
2406Then the mouse event can be retrieved with <var class=
2407"LITERAL">getmouse()</var>.</p>
2408<p>The code approximately looks like this:</p>
2409<table border="0" bgcolor="#E0E0E0" width="100%">
2410<tr>
2411<td>
2412<pre class="PROGRAMLISTING">
2413<font color="#000000"> MEVENT event;
2414
2415 ch = getch();
2416 if(ch == KEY_MOUSE)
2417 if(getmouse(&amp;event) == OK)
2418 . /* Do some thing with the event */
2419 .
2420 .</font>
2421</pre></td>
2422</tr>
2423</table>
2424<p>getmouse() returns the event into the pointer given to it. It's
2425a structure which contains</p>
2426<table border="0" bgcolor="#E0E0E0" width="100%">
2427<tr>
2428<td>
2429<pre class="PROGRAMLISTING">
2430<font color="#000000"> typedef struct
2431 {
2432 short id; /* ID to distinguish multiple devices */
2433 int x, y, z; /* event coordinates */
2434 mmask_t bstate; /* button state bits */
2435 } </font>
2436</pre></td>
2437</tr>
2438</table>
2439<p>The <var class="LITERAL">bstate</var> is the main variable we
2440are interested in. It tells the button state of the mouse.</p>
2441<p>Then with a code snippet like the following, we can find out
2442what happened.</p>
2443<table border="0" bgcolor="#E0E0E0" width="100%">
2444<tr>
2445<td>
2446<pre class="PROGRAMLISTING">
2447<font color="#000000"> if(event.bstate &amp; BUTTON1_PRESSED)
2448 printw("Left Button Pressed");</font>
2449</pre></td>
2450</tr>
2451</table>
2452</div>
2453<div class="SECT2">
2454<hr>
2455<h3 class="SECT2"><a name="MOUSETOGETHER" id="MOUSETOGETHER">12.3.
2456Putting it all Together</a></h3>
2457<p>That's pretty much interfacing with mouse. Let's create the same
2458menu and enable mouse interaction. To make things simpler, key
2459handling is removed.</p>
2460<div class="EXAMPLE"><a name="BMOME" id="BMOME"></a>
2461<p><b>Example 11. Access the menu with mouse !!!</b></p>
2462<table border="0" bgcolor="#E0E0E0" width="100%">
2463<tr>
2464<td>
2465<pre class="PROGRAMLISTING">
2466<font color="#000000"><span class=
2467"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
2468
2469#define WIDTH 30
2470#define HEIGHT 10
2471
2472int startx = 0;
2473int starty = 0;
2474
2475char *choices[] = { "Choice 1",
2476 "Choice 2",
2477 "Choice 3",
2478 "Choice 4",
2479 "Exit",
2480 };
2481
2482int n_choices = sizeof(choices) / sizeof(char *);
2483
2484void print_menu(WINDOW *menu_win, int highlight);
2485void report_choice(int mouse_x, int mouse_y, int *p_choice);
2486
2487int main()
2488{ int c, choice = 0;
2489 WINDOW *menu_win;
2490 MEVENT event;
2491
2492 /* Initialize curses */
2493 initscr();
2494 clear();
2495 noecho();
2496 cbreak(); //Line buffering disabled. pass on everything
2497
2498 /* Try to put the window in the middle of screen */
2499 startx = (80 - WIDTH) / 2;
2500 starty = (24 - HEIGHT) / 2;
2501
2502 attron(A_REVERSE);
2503 mvprintw(23, 1, "Click on Exit to quit (Works best in a virtual console)");
2504 refresh();
2505 attroff(A_REVERSE);
2506
2507 /* Print the menu for the first time */
2508 menu_win = newwin(HEIGHT, WIDTH, starty, startx);
2509 print_menu(menu_win, 1);
2510 /* Get all the mouse events */
2511 mousemask(ALL_MOUSE_EVENTS, NULL);
2512
2513 while(1)
2514 { c = wgetch(menu_win);
2515 switch(c)
2516 { case KEY_MOUSE:
2517 if(getmouse(&amp;event) == OK)
2518 { /* When the user clicks left mouse button */
2519 if(event.bstate &amp; BUTTON1_PRESSED)
2520 { report_choice(event.x + 1, event.y + 1, &amp;choice);
2521 if(choice == -1) //Exit chosen
2522 goto end;
2523 mvprintw(22, 1, "Choice made is : %d String Chosen is \"%10s\"", choice, choices[choice - 1]);
2524 refresh();
2525 }
2526 }
2527 print_menu(menu_win, choice);
2528 break;
2529 }
2530 }
2531end:
2532 endwin();
2533 return 0;
2534}
2535
2536
2537void print_menu(WINDOW *menu_win, int highlight)
2538{
2539 int x, y, i;
2540
2541 x = 2;
2542 y = 2;
2543 box(menu_win, 0, 0);
2544 for(i = 0; i &lt; n_choices; ++i)
2545 { if(highlight == i + 1)
2546 { wattron(menu_win, A_REVERSE);
2547 mvwprintw(menu_win, y, x, "%s", choices[i]);
2548 wattroff(menu_win, A_REVERSE);
2549 }
2550 else
2551 mvwprintw(menu_win, y, x, "%s", choices[i]);
2552 ++y;
2553 }
2554 wrefresh(menu_win);
2555}
2556
2557/* Report the choice according to mouse position */
2558void report_choice(int mouse_x, int mouse_y, int *p_choice)
2559{ int i,j, choice;
2560
2561 i = startx + 2;
2562 j = starty + 3;
2563
2564 for(choice = 0; choice &lt; n_choices; ++choice)
2565 if(mouse_y == j + choice &amp;&amp; mouse_x &gt;= i &amp;&amp; mouse_x &lt;= i + strlen(choices[choice]))
2566 { if(choice == n_choices - 1)
2567 *p_choice = -1;
2568 else
2569 *p_choice = choice + 1;
2570 break;
2571 }
2572}</span></font>
2573</pre></td>
2574</tr>
2575</table>
2576</div>
2577</div>
2578<div class="SECT2">
2579<hr>
2580<h3 class="SECT2"><a name="MISCMOUSEFUNCS" id=
2581"MISCMOUSEFUNCS">12.4. Miscellaneous Functions</a></h3>
2582<p>The functions mouse_trafo() and wmouse_trafo() can be used to
2583convert to mouse co-ordinates to screen relative co-ordinates. See
2584curs_mouse(3X) man page for details.</p>
2585<p>The mouseinterval function sets the maximum time (in thousands
2586of a second) that can elapse between press and release events in
2587order for them to be recognized as a click. This function returns
2588the previous interval value. The default is one fifth of a
2589second.</p>
2590</div>
2591</div>
2592<div class="SECT1">
2593<hr>
2594<h2 class="SECT1"><a name="SCREEN" id="SCREEN">13. Screen
2595Manipulation</a></h2>
2596<p>In this section, we will look into some functions, which allow
2597us to manage the screen efficiently and to write some fancy
2598programs. This is especially important in writing games.</p>
2599<div class="SECT2">
2600<hr>
2601<h3 class="SECT2"><a name="GETYX" id="GETYX">13.1. getyx()
2602functions</a></h3>
2603<p>The function <var class="LITERAL">getyx()</var> can be used to
2604find out the present cursor co-ordinates. It will fill the values
2605of x and y co-ordinates in the arguments given to it. Since getyx()
2606is a macro you don't have to pass the address of the variables. It
2607can be called as</p>
2608<table border="0" bgcolor="#E0E0E0" width="100%">
2609<tr>
2610<td>
2611<pre class="PROGRAMLISTING">
2612<font color="#000000"> getyx(win, y, x);
2613 /* win: window pointer
2614 * y, x: y, x co-ordinates will be put into this variables
2615 */</font>
2616</pre></td>
2617</tr>
2618</table>
2619<p>The function getparyx() gets the beginning co-ordinates of the
2620sub window relative to the main window. This is some times useful
2621to update a sub window. When designing fancy stuff like writing
2622multiple menus, it becomes difficult to store the menu positions,
2623their first option co-ordinates etc. A simple solution to this
2624problem, is to create menus in sub windows and later find the
2625starting co-ordinates of the menus by using getparyx().</p>
2626<p>The functions getbegyx() and getmaxyx() store current window's
2627beginning and maximum co-ordinates. These functions are useful in
2628the same way as above in managing the windows and sub windows
2629effectively.</p>
2630</div>
2631<div class="SECT2">
2632<hr>
2633<h3 class="SECT2"><a name="SCREENDUMP" id="SCREENDUMP">13.2. Screen
2634Dumping</a></h3>
2635<p>While writing games, some times it becomes necessary to store
2636the state of the screen and restore it back to the same state. The
2637function scr_dump() can be used to dump the screen contents to a
2638file given as an argument. Later it can be restored by scr_restore
2639function. These two simple functions can be used effectively to
2640maintain a fast moving game with changing scenarios.</p>
2641</div>
2642<div class="SECT2">
2643<hr>
2644<h3 class="SECT2"><a name="WINDOWDUMP" id="WINDOWDUMP">13.3. Window
2645Dumping</a></h3>
2646<p>To store and restore windows, the functions <var class=
2647"LITERAL">putwin()</var> and <var class="LITERAL">getwin()</var>
2648can be used. <var class="LITERAL">putwin()</var> puts the present
2649window state into a file, which can be later restored by
2650<var class="LITERAL">getwin()</var>.</p>
2651<p>The function <var class="LITERAL">copywin()</var> can be used to
2652copy a window completely onto another window. It takes the source
2653and destination windows as parameters and according to the
2654rectangle specified, it copies the rectangular region from source
2655to destination window. It's last parameter specifies whether to
2656overwrite or just overlay the contents on to the destination
2657window. If this argument is true, then the copying is
2658non-destructive.</p>
2659</div>
2660</div>
2661<div class="SECT1">
2662<hr>
2663<h2 class="SECT1"><a name="MISC" id="MISC">14. Miscellaneous
2664features</a></h2>
2665<p>Now you know enough features to write a good curses program,
2666with all bells and whistles. There are some miscellaneous functions
2667which are useful in various cases. Let's go headlong into some of
2668those.</p>
2669<div class="SECT2">
2670<hr>
2671<h3 class="SECT2"><a name="CURSSET" id="CURSSET">14.1.
2672curs_set()</a></h3>
2673<p>This function can be used to make the cursor invisible. The
2674parameter to this function should be</p>
2675<table border="0" bgcolor="#E0E0E0" width="100%">
2676<tr>
2677<td>
2678<pre class="PROGRAMLISTING">
2679<font color="#000000"> 0 : invisible or
2680 1 : normal or
2681 2 : very visible.</font>
2682</pre></td>
2683</tr>
2684</table>
2685</div>
2686<div class="SECT2">
2687<hr>
2688<h3 class="SECT2"><a name="TEMPLEAVE" id="TEMPLEAVE">14.2.
2689Temporarily Leaving Curses mode</a></h3>
2690<p>Some times you may want to get back to cooked mode (normal line
2691buffering mode) temporarily. In such a case you will first need to
2692save the tty modes with a call to <var class=
2693"LITERAL">def_prog_mode()</var> and then call <var class=
2694"LITERAL">endwin()</var> to end the curses mode. This will leave
2695you in the original tty mode. To get back to curses once you are
2696done, call <var class="LITERAL">reset_prog_mode()</var> . This
2697function returns the tty to the state stored by <var class=
2698"LITERAL">def_prog_mode()</var>. Then do refresh(), and you are
2699back to the curses mode. Here is an example showing the sequence of
2700things to be done.</p>
2701<div class="EXAMPLE"><a name="BTELE" id="BTELE"></a>
2702<p><b>Example 12. Temporarily Leaving Curses Mode</b></p>
2703<table border="0" bgcolor="#E0E0E0" width="100%">
2704<tr>
2705<td>
2706<pre class="PROGRAMLISTING">
2707<font color="#000000"><span class=
2708"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
2709
2710int main()
2711{
2712 initscr(); /* Start curses mode */
2713 printw("Hello World !!!\n"); /* Print Hello World */
2714 refresh(); /* Print it on to the real screen */
2715 def_prog_mode(); /* Save the tty modes */
2716 endwin(); /* End curses mode temporarily */
2717 system("/bin/sh"); /* Do whatever you like in cooked mode */
2718 reset_prog_mode(); /* Return to the previous tty mode*/
2719 /* stored by def_prog_mode() */
2720 refresh(); /* Do refresh() to restore the */
2721 /* Screen contents */
2722 printw("Another String\n"); /* Back to curses use the full */
2723 refresh(); /* capabilities of curses */
2724 endwin(); /* End curses mode */
2725
2726 return 0;
2727}</span></font>
2728</pre></td>
2729</tr>
2730</table>
2731</div>
2732</div>
2733<div class="SECT2">
2734<hr>
2735<h3 class="SECT2"><a name="ACSVARS" id="ACSVARS">14.3. ACS_
2736variables</a></h3>
2737<p>If you have ever programmed in DOS, you know about those nifty
2738characters in extended character set. They are printable only on
2739some terminals. NCURSES functions like <var class=
2740"LITERAL">box()</var> use these characters. All these variables
2741start with ACS meaning alternative character set. You might have
2742noticed me using these characters in some of the programs above.
2743Here's an example showing all the characters.</p>
2744<div class="EXAMPLE"><a name="BACSVARS" id="BACSVARS"></a>
2745<p><b>Example 13. ACS Variables Example</b></p>
2746<table border="0" bgcolor="#E0E0E0" width="100%">
2747<tr>
2748<td>
2749<pre class="PROGRAMLISTING">
2750<font color="#000000"><span class=
2751"INLINEMEDIAOBJECT">#include &lt;ncurses.h&gt;
2752
2753int main()
2754{
2755 initscr();
2756
2757 printw("Upper left corner "); addch(ACS_ULCORNER); printw("\n");
2758 printw("Lower left corner "); addch(ACS_LLCORNER); printw("\n");
2759 printw("Lower right corner "); addch(ACS_LRCORNER); printw("\n");
2760 printw("Tee pointing right "); addch(ACS_LTEE); printw("\n");
2761 printw("Tee pointing left "); addch(ACS_RTEE); printw("\n");
2762 printw("Tee pointing up "); addch(ACS_BTEE); printw("\n");
2763 printw("Tee pointing down "); addch(ACS_TTEE); printw("\n");
2764 printw("Horizontal line "); addch(ACS_HLINE); printw("\n");
2765 printw("Vertical line "); addch(ACS_VLINE); printw("\n");
2766 printw("Large Plus or cross over "); addch(ACS_PLUS); printw("\n");
2767 printw("Scan Line 1 "); addch(ACS_S1); printw("\n");
2768 printw("Scan Line 3 "); addch(ACS_S3); printw("\n");
2769 printw("Scan Line 7 "); addch(ACS_S7); printw("\n");
2770 printw("Scan Line 9 "); addch(ACS_S9); printw("\n");
2771 printw("Diamond "); addch(ACS_DIAMOND); printw("\n");
2772 printw("Checker board (stipple) "); addch(ACS_CKBOARD); printw("\n");
2773 printw("Degree Symbol "); addch(ACS_DEGREE); printw("\n");
2774 printw("Plus/Minus Symbol "); addch(ACS_PLMINUS); printw("\n");
2775 printw("Bullet "); addch(ACS_BULLET); printw("\n");
2776 printw("Arrow Pointing Left "); addch(ACS_LARROW); printw("\n");
2777 printw("Arrow Pointing Right "); addch(ACS_RARROW); printw("\n");
2778 printw("Arrow Pointing Down "); addch(ACS_DARROW); printw("\n");
2779 printw("Arrow Pointing Up "); addch(ACS_UARROW); printw("\n");
2780 printw("Board of squares "); addch(ACS_BOARD); printw("\n");
2781 printw("Lantern Symbol "); addch(ACS_LANTERN); printw("\n");
2782 printw("Solid Square Block "); addch(ACS_BLOCK); printw("\n");
2783 printw("Less/Equal sign "); addch(ACS_LEQUAL); printw("\n");
2784 printw("Greater/Equal sign "); addch(ACS_GEQUAL); printw("\n");
2785 printw("Pi "); addch(ACS_PI); printw("\n");
2786 printw("Not equal "); addch(ACS_NEQUAL); printw("\n");
2787 printw("UK pound sign "); addch(ACS_STERLING); printw("\n");
2788
2789 refresh();
2790 getch();
2791 endwin();
2792
2793 return 0;
2794}</span></font>
2795</pre></td>
2796</tr>
2797</table>
2798</div>
2799</div>
2800</div>
2801<div class="SECT1">
2802<hr>
2803<h2 class="SECT1"><a name="OTHERLIB" id="OTHERLIB">15. Other
2804libraries</a></h2>
2805<p>Apart from the curses library, there are few text mode
2806libraries, which provide more functionality and a lot of features.
2807The following sections explain three standard libraries which are
2808usually distributed along with curses.</p>
2809</div>
2810<div class="SECT1">
2811<hr>
2812<h2 class="SECT1"><a name="PANELS" id="PANELS">16. Panel
2813Library</a></h2>
2814<p>Now that you are proficient in curses, you wanted to do some
2815thing big. You created a lot of overlapping windows to give a
2816professional windows-type look. Unfortunately, it soon becomes
2817difficult to manage these. The multiple refreshes, updates plunge
2818you into a nightmare. The overlapping windows create blotches,
2819whenever you forget to refresh the windows in the proper order.</p>
2820<p>Don't despair. There's an elegant solution provided in panels
2821library. In the words of developers of ncurses</p>
2822<p><em>When your interface design is such that windows may dive
2823deeper into the visibility stack or pop to the top at runtime, the
2824resulting book-keeping can be tedious and difficult to get right.
2825Hence the panels library.</em></p>
2826<p>If you have lot of overlapping windows, then panels library is
2827the way to go. It obviates the need of doing series of
2828wnoutrefresh(), doupdate() and relieves the burden of doing it
2829correctly(bottom up). The library maintains information about the
2830order of windows, their overlapping and update the screen properly.
2831So why wait? Let's take a close peek into panels.</p>
2832<div class="SECT2">
2833<hr>
2834<h3 class="SECT2"><a name="PANELBASICS" id="PANELBASICS">16.1. The
2835Basics</a></h3>
2836<p>Panel object is a window that is implicitly treated as part of a
2837deck including all other panel objects. The deck is treated as a
2838stack with the top panel being completely visible and the other
2839panels may or may not be obscured according to their positions. So
2840the basic idea is to create a stack of overlapping panels and use
2841panels library to display them correctly. There is a function
2842similar to refresh() which, when called , displays panels in the
2843correct order. Functions are provided to hide or show panels, move
2844panels, change its size etc.. The overlapping problem is managed by
2845the panels library during all the calls to these functions.</p>
2846<p>The general flow of a panel program goes like this:</p>
2847<ol type="1">
2848<li>
2849<p>Create the windows (with newwin()) to be attached to the
2850panels.</p>
2851</li>
2852<li>
2853<p>Create panels with the chosen visibility order. Stack them up
2854according to the desired visibility. The function new_panel() is
2855used to created panels.</p>
2856</li>
2857<li>
2858<p>Call update_panels() to write the panels to the virtual screen
2859in correct visibility order. Do a doupdate() to show it on the
2860screen.</p>
2861</li>
2862<li>
2863<p>Mainpulate the panels with show_panel(), hide_panel(),
2864move_panel() etc. Make use of helper functions like panel_hidden()
2865and panel_window(). Make use of user pointer to store custom data
2866for a panel. Use the functions set_panel_userptr() and
2867panel_userptr() to set and get the user pointer for a panel.</p>
2868</li>
2869<li>
2870<p>When you are done with the panel use del_panel() to delete the
2871panel.</p>
2872</li>
2873</ol>
2874<p>Let's make the concepts clear, with some programs. The following
2875is a simple program which creates 3 overlapping panels and shows
2876them on the screen.</p>
2877</div>
2878<div class="SECT2">
2879<hr>
2880<h3 class="SECT2"><a name="COMPILEPANELS" id="COMPILEPANELS">16.2.
2881Compiling With the Panels Library</a></h3>
2882<p>To use panels library functions, you have to include panel.h and
2883to link the program with panels library the flag -lpanel should be
2884added along with -lncurses in that order.</p>
2885<table border="0" bgcolor="#E0E0E0" width="100%">
2886<tr>
2887<td>
2888<pre class="PROGRAMLISTING">
2889<font color="#000000"> #include &lt;panel.h&gt;
2890 .
2891 .
2892 .
2893
2894 compile and link: gcc &lt;program file&gt; -lpanel -lncurses</font>
2895</pre></td>
2896</tr>
2897</table>
2898<div class="EXAMPLE"><a name="PPASI" id="PPASI"></a>
2899<p><b>Example 14. Panel basics</b></p>
2900<table border="0" bgcolor="#E0E0E0" width="100%">
2901<tr>
2902<td>
2903<pre class="PROGRAMLISTING">
2904<font color="#000000"><span class=
2905"INLINEMEDIAOBJECT">#include &lt;panel.h&gt;
2906
2907int main()
2908{ WINDOW *my_wins[3];
2909 PANEL *my_panels[3];
2910 int lines = 10, cols = 40, y = 2, x = 4, i;
2911
2912 initscr();
2913 cbreak();
2914 noecho();
2915
2916 /* Create windows for the panels */
2917 my_wins[0] = newwin(lines, cols, y, x);
2918 my_wins[1] = newwin(lines, cols, y + 1, x + 5);
2919 my_wins[2] = newwin(lines, cols, y + 2, x + 10);
2920
2921 /*
2922 * Create borders around the windows so that you can see the effect
2923 * of panels
2924 */
2925 for(i = 0; i &lt; 3; ++i)
2926 box(my_wins[i], 0, 0);
2927
2928 /* Attach a panel to each window */ /* Order is bottom up */
2929 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
2930 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
2931 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
2932
2933 /* Update the stacking order. 2nd panel will be on top */
2934 update_panels();
2935
2936 /* Show it on the screen */
2937 doupdate();
2938
2939 getch();
2940 endwin();
2941}
2942</span></font>
2943</pre></td>
2944</tr>
2945</table>
2946</div>
2947<p>As you can see, above program follows a simple flow as
2948explained. The windows are created with newwin() and then they are
2949attached to panels with new_panel(). As we attach one panel after
2950another, the stack of panels gets updated. To put them on screen
2951update_panels() and doupdate() are called.</p>
2952</div>
2953<div class="SECT2">
2954<hr>
2955<h3 class="SECT2"><a name="PANELBROWSING" id="PANELBROWSING">16.3.
2956Panel Window Browsing</a></h3>
2957<p>A slightly complicated example is given below. This program
2958creates 3 windows which can be cycled through using tab. Have a
2959look at the code.</p>
2960<div class="EXAMPLE"><a name="PPABR" id="PPABR"></a>
2961<p><b>Example 15. Panel Window Browsing Example</b></p>
2962<table border="0" bgcolor="#E0E0E0" width="100%">
2963<tr>
2964<td>
2965<pre class="PROGRAMLISTING">
2966<font color="#000000"><span class=
2967"INLINEMEDIAOBJECT">#include &lt;panel.h&gt;
2968
2969#define NLINES 10
2970#define NCOLS 40
2971
2972void init_wins(WINDOW **wins, int n);
2973void win_show(WINDOW *win, char *label, int label_color);
2974void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
2975
2976int main()
2977{ WINDOW *my_wins[3];
2978 PANEL *my_panels[3];
2979 PANEL *top;
2980 int ch;
2981
2982 /* Initialize curses */
2983 initscr();
2984 start_color();
2985 cbreak();
2986 noecho();
2987 keypad(stdscr, TRUE);
2988
2989 /* Initialize all the colors */
2990 init_pair(1, COLOR_RED, COLOR_BLACK);
2991 init_pair(2, COLOR_GREEN, COLOR_BLACK);
2992 init_pair(3, COLOR_BLUE, COLOR_BLACK);
2993 init_pair(4, COLOR_CYAN, COLOR_BLACK);
2994
2995 init_wins(my_wins, 3);
2996
2997 /* Attach a panel to each window */ /* Order is bottom up */
2998 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
2999 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3000 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3001
3002 /* Set up the user pointers to the next panel */
3003 set_panel_userptr(my_panels[0], my_panels[1]);
3004 set_panel_userptr(my_panels[1], my_panels[2]);
3005 set_panel_userptr(my_panels[2], my_panels[0]);
3006
3007 /* Update the stacking order. 2nd panel will be on top */
3008 update_panels();
3009
3010 /* Show it on the screen */
3011 attron(COLOR_PAIR(4));
3012 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3013 attroff(COLOR_PAIR(4));
3014 doupdate();
3015
3016 top = my_panels[2];
3017 while((ch = getch()) != KEY_F(1))
3018 { switch(ch)
3019 { case 9:
3020 top = (PANEL *)panel_userptr(top);
3021 top_panel(top);
3022 break;
3023 }
3024 update_panels();
3025 doupdate();
3026 }
3027 endwin();
3028 return 0;
3029}
3030
3031/* Put all the windows */
3032void init_wins(WINDOW **wins, int n)
3033{ int x, y, i;
3034 char label[80];
3035
3036 y = 2;
3037 x = 10;
3038 for(i = 0; i &lt; n; ++i)
3039 { wins[i] = newwin(NLINES, NCOLS, y, x);
3040 sprintf(label, "Window Number %d", i + 1);
3041 win_show(wins[i], label, i + 1);
3042 y += 3;
3043 x += 7;
3044 }
3045}
3046
3047/* Show the window with a border and a label */
3048void win_show(WINDOW *win, char *label, int label_color)
3049{ int startx, starty, height, width;
3050
3051 getbegyx(win, starty, startx);
3052 getmaxyx(win, height, width);
3053
3054 box(win, 0, 0);
3055 mvwaddch(win, 2, 0, ACS_LTEE);
3056 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3057 mvwaddch(win, 2, width - 1, ACS_RTEE);
3058
3059 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3060}
3061
3062void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3063{ int length, x, y;
3064 float temp;
3065
3066 if(win == NULL)
3067 win = stdscr;
3068 getyx(win, y, x);
3069 if(startx != 0)
3070 x = startx;
3071 if(starty != 0)
3072 y = starty;
3073 if(width == 0)
3074 width = 80;
3075
3076 length = strlen(string);
3077 temp = (width - length)/ 2;
3078 x = startx + (int)temp;
3079 wattron(win, color);
3080 mvwprintw(win, y, x, "%s", string);
3081 wattroff(win, color);
3082 refresh();
3083}</span></font>
3084</pre></td>
3085</tr>
3086</table>
3087</div>
3088</div>
3089<div class="SECT2">
3090<hr>
3091<h3 class="SECT2"><a name="USERPTRUSING" id="USERPTRUSING">16.4.
3092Using User Pointers</a></h3>
3093<p>In the above example I used user pointers to find out the next
3094window in the cycle. We can attach custom information to the panel
3095by specifying a user pointer, which can point to any information
3096you want to store. In this case I stored the pointer to the next
3097panel in the cycle. User pointer for a panel can be set with the
3098function <var class="LITERAL">set_panel_userptr()</var>. It can be
3099accessed using the function <var class=
3100"LITERAL">panel_userptr()</var> which will return the user pointer
3101for the panel given as argument. After finding the next panel in
3102the cycle It's brought to the top by the function top_panel(). This
3103function brings the panel given as argument to the top of the panel
3104stack.</p>
3105</div>
3106<div class="SECT2">
3107<hr>
3108<h3 class="SECT2"><a name="PANELMOVERESIZE" id=
3109"PANELMOVERESIZE">16.5. Moving and Resizing Panels</a></h3>
3110<p>The function <var class="LITERAL">move_panel()</var> can be used
3111to move a panel to the desired location. It does not change the
3112position of the panel in the stack. Make sure that you use
3113move_panel() instead mvwin() on the window associated with the
3114panel.</p>
3115<p>Resizing a panel is slightly complex. There is no straight
3116forward function just to resize the window associated with a panel.
3117A solution to resize a panel is to create a new window with the
3118desired sizes, change the window associated with the panel using
3119replace_panel(). Don't forget to delete the old window. The window
3120associated with a panel can be found by using the function
3121panel_window().</p>
3122<p>The following program shows these concepts, in supposedly simple
3123program. You can cycle through the window with &lt;TAB&gt; as
3124usual. To resize or move the active panel press 'r' for resize 'm'
3125for moving. Then use arrow keys to resize or move it to the desired
3126way and press enter to end your resizing or moving. This example
3127makes use of user data to get the required data to do the
3128operations.</p>
3129<div class="EXAMPLE"><a name="PPARE" id="PPARE"></a>
3130<p><b>Example 16. Panel Moving and Resizing example</b></p>
3131<table border="0" bgcolor="#E0E0E0" width="100%">
3132<tr>
3133<td>
3134<pre class="PROGRAMLISTING">
3135<font color="#000000"><span class=
3136"INLINEMEDIAOBJECT">#include &lt;panel.h&gt;
3137
3138typedef struct _PANEL_DATA {
3139 int x, y, w, h;
3140 char label[80];
3141 int label_color;
3142 PANEL *next;
3143}PANEL_DATA;
3144
3145#define NLINES 10
3146#define NCOLS 40
3147
3148void init_wins(WINDOW **wins, int n);
3149void win_show(WINDOW *win, char *label, int label_color);
3150void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3151void set_user_ptrs(PANEL **panels, int n);
3152
3153int main()
3154{ WINDOW *my_wins[3];
3155 PANEL *my_panels[3];
3156 PANEL_DATA *top;
3157 PANEL *stack_top;
3158 WINDOW *temp_win, *old_win;
3159 int ch;
3160 int newx, newy, neww, newh;
3161 int size = FALSE, move = FALSE;
3162
3163 /* Initialize curses */
3164 initscr();
3165 start_color();
3166 cbreak();
3167 noecho();
3168 keypad(stdscr, TRUE);
3169
3170 /* Initialize all the colors */
3171 init_pair(1, COLOR_RED, COLOR_BLACK);
3172 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3173 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3174 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3175
3176 init_wins(my_wins, 3);
3177
3178 /* Attach a panel to each window */ /* Order is bottom up */
3179 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3180 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3181 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3182
3183 set_user_ptrs(my_panels, 3);
3184 /* Update the stacking order. 2nd panel will be on top */
3185 update_panels();
3186
3187 /* Show it on the screen */
3188 attron(COLOR_PAIR(4));
3189 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3190 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3191 attroff(COLOR_PAIR(4));
3192 doupdate();
3193
3194 stack_top = my_panels[2];
3195 top = (PANEL_DATA *)panel_userptr(stack_top);
3196 newx = top-&gt;x;
3197 newy = top-&gt;y;
3198 neww = top-&gt;w;
3199 newh = top-&gt;h;
3200 while((ch = getch()) != KEY_F(1))
3201 { switch(ch)
3202 { case 9: /* Tab */
3203 top = (PANEL_DATA *)panel_userptr(stack_top);
3204 top_panel(top-&gt;next);
3205 stack_top = top-&gt;next;
3206 top = (PANEL_DATA *)panel_userptr(stack_top);
3207 newx = top-&gt;x;
3208 newy = top-&gt;y;
3209 neww = top-&gt;w;
3210 newh = top-&gt;h;
3211 break;
3212 case 'r': /* Re-Size*/
3213 size = TRUE;
3214 attron(COLOR_PAIR(4));
3215 mvprintw(LINES - 4, 0, "Entered Resizing :Use Arrow Keys to resize and press &lt;ENTER&gt; to end resizing");
3216 refresh();
3217 attroff(COLOR_PAIR(4));
3218 break;
3219 case 'm': /* Move */
3220 attron(COLOR_PAIR(4));
3221 mvprintw(LINES - 4, 0, "Entered Moving: Use Arrow Keys to Move and press &lt;ENTER&gt; to end moving");
3222 refresh();
3223 attroff(COLOR_PAIR(4));
3224 move = TRUE;
3225 break;
3226 case KEY_LEFT:
3227 if(size == TRUE)
3228 { --newx;
3229 ++neww;
3230 }
3231 if(move == TRUE)
3232 --newx;
3233 break;
3234 case KEY_RIGHT:
3235 if(size == TRUE)
3236 { ++newx;
3237 --neww;
3238 }
3239 if(move == TRUE)
3240 ++newx;
3241 break;
3242 case KEY_UP:
3243 if(size == TRUE)
3244 { --newy;
3245 ++newh;
3246 }
3247 if(move == TRUE)
3248 --newy;
3249 break;
3250 case KEY_DOWN:
3251 if(size == TRUE)
3252 { ++newy;
3253 --newh;
3254 }
3255 if(move == TRUE)
3256 ++newy;
3257 break;
3258 case 10: /* Enter */
3259 move(LINES - 4, 0);
3260 clrtoeol();
3261 refresh();
3262 if(size == TRUE)
3263 { old_win = panel_window(stack_top);
3264 temp_win = newwin(newh, neww, newy, newx);
3265 replace_panel(stack_top, temp_win);
3266 win_show(temp_win, top-&gt;label, top-&gt;label_color);
3267 delwin(old_win);
3268 size = FALSE;
3269 }
3270 if(move == TRUE)
3271 { move_panel(stack_top, newy, newx);
3272 move = FALSE;
3273 }
3274 break;
3275
3276 }
3277 attron(COLOR_PAIR(4));
3278 mvprintw(LINES - 3, 0, "Use 'm' for moving, 'r' for resizing");
3279 mvprintw(LINES - 2, 0, "Use tab to browse through the windows (F1 to Exit)");
3280 attroff(COLOR_PAIR(4));
3281 refresh();
3282 update_panels();
3283 doupdate();
3284 }
3285 endwin();
3286 return 0;
3287}
3288
3289/* Put all the windows */
3290void init_wins(WINDOW **wins, int n)
3291{ int x, y, i;
3292 char label[80];
3293
3294 y = 2;
3295 x = 10;
3296 for(i = 0; i &lt; n; ++i)
3297 { wins[i] = newwin(NLINES, NCOLS, y, x);
3298 sprintf(label, "Window Number %d", i + 1);
3299 win_show(wins[i], label, i + 1);
3300 y += 3;
3301 x += 7;
3302 }
3303}
3304
3305/* Set the PANEL_DATA structures for individual panels */
3306void set_user_ptrs(PANEL **panels, int n)
3307{ PANEL_DATA *ptrs;
3308 WINDOW *win;
3309 int x, y, w, h, i;
3310 char temp[80];
3311
3312 ptrs = (PANEL_DATA *)calloc(n, sizeof(PANEL_DATA));
3313
3314 for(i = 0;i &lt; n; ++i)
3315 { win = panel_window(panels[i]);
3316 getbegyx(win, y, x);
3317 getmaxyx(win, h, w);
3318 ptrs[i].x = x;
3319 ptrs[i].y = y;
3320 ptrs[i].w = w;
3321 ptrs[i].h = h;
3322 sprintf(temp, "Window Number %d", i + 1);
3323 strcpy(ptrs[i].label, temp);
3324 ptrs[i].label_color = i + 1;
3325 if(i + 1 == n)
3326 ptrs[i].next = panels[0];
3327 else
3328 ptrs[i].next = panels[i + 1];
3329 set_panel_userptr(panels[i], &amp;ptrs[i]);
3330 }
3331}
3332
3333/* Show the window with a border and a label */
3334void win_show(WINDOW *win, char *label, int label_color)
3335{ int startx, starty, height, width;
3336
3337 getbegyx(win, starty, startx);
3338 getmaxyx(win, height, width);
3339
3340 box(win, 0, 0);
3341 mvwaddch(win, 2, 0, ACS_LTEE);
3342 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3343 mvwaddch(win, 2, width - 1, ACS_RTEE);
3344
3345 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3346}
3347
3348void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3349{ int length, x, y;
3350 float temp;
3351
3352 if(win == NULL)
3353 win = stdscr;
3354 getyx(win, y, x);
3355 if(startx != 0)
3356 x = startx;
3357 if(starty != 0)
3358 y = starty;
3359 if(width == 0)
3360 width = 80;
3361
3362 length = strlen(string);
3363 temp = (width - length)/ 2;
3364 x = startx + (int)temp;
3365 wattron(win, color);
3366 mvwprintw(win, y, x, "%s", string);
3367 wattroff(win, color);
3368 refresh();
3369}</span></font>
3370</pre></td>
3371</tr>
3372</table>
3373</div>
3374<p>Concentrate on the main while loop. Once it finds out the type
3375of key pressed, it takes appropriate action. If 'r' is pressed
3376resizing mode is started. After this the new sizes are updated as
3377the user presses the arrow keys. When the user presses
3378&lt;ENTER&gt; present selection ends and panel is resized by using
3379the concept explained. While in resizing mode the program doesn't
3380show how the window is getting resized. It's left as an exercise to
3381the reader to print a dotted border while it gets resized to a new
3382position.</p>
3383<p>When the user presses 'm' the move mode starts. This is a bit
3384simpler than resizing. As the arrow keys are pressed the new
3385position is updated and pressing of &lt;ENTER&gt; causes the panel
3386to be moved by calling the function move_panel().</p>
3387<p>In this program the user data which is represented as
3388PANEL_DATA, plays very important role in finding the associated
3389information with a panel. As written in the comments, the
3390PANEL_DATA stores the panel sizes, label, label color and a pointer
3391to the next panel in the cycle.</p>
3392</div>
3393<div class="SECT2">
3394<hr>
3395<h3 class="SECT2"><a name="PANELSHOWHIDE" id="PANELSHOWHIDE">16.6.
3396Hiding and Showing Panels</a></h3>
3397<p>A Panel can be hidden by using the function hide_panel(). This
3398function merely removes it form the stack of panels, thus hiding it
3399on the screen once you do update_panels() and doupdate(). It
3400doesn't destroy the PANEL structure associated with the hidden
3401panel. It can be shown again by using the show_panel()
3402function.</p>
3403<p>The following program shows the hiding of panels. Press 'a' or
3404'b' or 'c' to show or hide first, second and third windows
3405respectively. It uses a user data with a small variable hide, which
3406keeps track of whether the window is hidden or not. For some reason
3407the function <var class="LITERAL">panel_hidden()</var> which tells
3408whether a panel is hidden or not is not working. A bug report was
3409also presented by Michael Andres <a href=
3410"http://www.geocrawler.com/archives/3/344/1999/9/0/2643549/"
3411target="_top">here</a></p>
3412<div class="EXAMPLE"><a name="PPAHI" id="PPAHI"></a>
3413<p><b>Example 17. Panel Hiding and Showing example</b></p>
3414<table border="0" bgcolor="#E0E0E0" width="100%">
3415<tr>
3416<td>
3417<pre class="PROGRAMLISTING">
3418<font color="#000000"><span class=
3419"INLINEMEDIAOBJECT">#include &lt;panel.h&gt;
3420
3421typedef struct _PANEL_DATA {
3422 int hide; /* TRUE if panel is hidden */
3423}PANEL_DATA;
3424
3425#define NLINES 10
3426#define NCOLS 40
3427
3428void init_wins(WINDOW **wins, int n);
3429void win_show(WINDOW *win, char *label, int label_color);
3430void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3431
3432int main()
3433{ WINDOW *my_wins[3];
3434 PANEL *my_panels[3];
3435 PANEL_DATA panel_datas[3];
3436 PANEL_DATA *temp;
3437 int ch;
3438
3439 /* Initialize curses */
3440 initscr();
3441 start_color();
3442 cbreak();
3443 noecho();
3444 keypad(stdscr, TRUE);
3445
3446 /* Initialize all the colors */
3447 init_pair(1, COLOR_RED, COLOR_BLACK);
3448 init_pair(2, COLOR_GREEN, COLOR_BLACK);
3449 init_pair(3, COLOR_BLUE, COLOR_BLACK);
3450 init_pair(4, COLOR_CYAN, COLOR_BLACK);
3451
3452 init_wins(my_wins, 3);
3453
3454 /* Attach a panel to each window */ /* Order is bottom up */
3455 my_panels[0] = new_panel(my_wins[0]); /* Push 0, order: stdscr-0 */
3456 my_panels[1] = new_panel(my_wins[1]); /* Push 1, order: stdscr-0-1 */
3457 my_panels[2] = new_panel(my_wins[2]); /* Push 2, order: stdscr-0-1-2 */
3458
3459 /* Initialize panel datas saying that nothing is hidden */
3460 panel_datas[0].hide = FALSE;
3461 panel_datas[1].hide = FALSE;
3462 panel_datas[2].hide = FALSE;
3463
3464 set_panel_userptr(my_panels[0], &amp;panel_datas[0]);
3465 set_panel_userptr(my_panels[1], &amp;panel_datas[1]);
3466 set_panel_userptr(my_panels[2], &amp;panel_datas[2]);
3467
3468 /* Update the stacking order. 2nd panel will be on top */
3469 update_panels();
3470
3471 /* Show it on the screen */
3472 attron(COLOR_PAIR(4));
3473 mvprintw(LINES - 3, 0, "Show or Hide a window with 'a'(first window) 'b'(Second Window) 'c'(Third Window)");
3474 mvprintw(LINES - 2, 0, "F1 to Exit");
3475
3476 attroff(COLOR_PAIR(4));
3477 doupdate();
3478
3479 while((ch = getch()) != KEY_F(1))
3480 { switch(ch)
3481 { case 'a':
3482 temp = (PANEL_DATA *)panel_userptr(my_panels[0]);
3483 if(temp-&gt;hide == FALSE)
3484 { hide_panel(my_panels[0]);
3485 temp-&gt;hide = TRUE;
3486 }
3487 else
3488 { show_panel(my_panels[0]);
3489 temp-&gt;hide = FALSE;
3490 }
3491 break;
3492 case 'b':
3493 temp = (PANEL_DATA *)panel_userptr(my_panels[1]);
3494 if(temp-&gt;hide == FALSE)
3495 { hide_panel(my_panels[1]);
3496 temp-&gt;hide = TRUE;
3497 }
3498 else
3499 { show_panel(my_panels[1]);
3500 temp-&gt;hide = FALSE;
3501 }
3502 break;
3503 case 'c':
3504 temp = (PANEL_DATA *)panel_userptr(my_panels[2]);
3505 if(temp-&gt;hide == FALSE)
3506 { hide_panel(my_panels[2]);
3507 temp-&gt;hide = TRUE;
3508 }
3509 else
3510 { show_panel(my_panels[2]);
3511 temp-&gt;hide = FALSE;
3512 }
3513 break;
3514 }
3515 update_panels();
3516 doupdate();
3517 }
3518 endwin();
3519 return 0;
3520}
3521
3522/* Put all the windows */
3523void init_wins(WINDOW **wins, int n)
3524{ int x, y, i;
3525 char label[80];
3526
3527 y = 2;
3528 x = 10;
3529 for(i = 0; i &lt; n; ++i)
3530 { wins[i] = newwin(NLINES, NCOLS, y, x);
3531 sprintf(label, "Window Number %d", i + 1);
3532 win_show(wins[i], label, i + 1);
3533 y += 3;
3534 x += 7;
3535 }
3536}
3537
3538/* Show the window with a border and a label */
3539void win_show(WINDOW *win, char *label, int label_color)
3540{ int startx, starty, height, width;
3541
3542 getbegyx(win, starty, startx);
3543 getmaxyx(win, height, width);
3544
3545 box(win, 0, 0);
3546 mvwaddch(win, 2, 0, ACS_LTEE);
3547 mvwhline(win, 2, 1, ACS_HLINE, width - 2);
3548 mvwaddch(win, 2, width - 1, ACS_RTEE);
3549
3550 print_in_middle(win, 1, 0, width, label, COLOR_PAIR(label_color));
3551}
3552
3553void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3554{ int length, x, y;
3555 float temp;
3556
3557 if(win == NULL)
3558 win = stdscr;
3559 getyx(win, y, x);
3560 if(startx != 0)
3561 x = startx;
3562 if(starty != 0)
3563 y = starty;
3564 if(width == 0)
3565 width = 80;
3566
3567 length = strlen(string);
3568 temp = (width - length)/ 2;
3569 x = startx + (int)temp;
3570 wattron(win, color);
3571 mvwprintw(win, y, x, "%s", string);
3572 wattroff(win, color);
3573 refresh();
3574}</span></font>
3575</pre></td>
3576</tr>
3577</table>
3578</div>
3579</div>
3580<div class="SECT2">
3581<hr>
3582<h3 class="SECT2"><a name="PANELABOVE" id="PANELABOVE">16.7.
3583panel_above() and panel_below() Functions</a></h3>
3584<p>The functions <var class="LITERAL">panel_above()</var> and
3585<var class="LITERAL">panel_below()</var> can be used to find out
3586the panel above and below a panel. If the argument to these
3587functions is NULL, then they return a pointer to bottom panel and
3588top panel respectively.</p>
3589</div>
3590</div>
3591<div class="SECT1">
3592<hr>
3593<h2 class="SECT1"><a name="MENUS" id="MENUS">17. Menus
3594Library</a></h2>
3595<p>The menus library provides a nice extension to basic curses,
3596through which you can create menus. It provides a set of functions
3597to create menus. But they have to be customized to give a nicer
3598look, with colors etc. Let's get into the details.</p>
3599<p>A menu is a screen display that assists the user to choose some
3600subset of a given set of items. To put it simple, a menu is a
3601collection of items from which one or more items can be chosen.
3602Some readers might not be aware of multiple item selection
3603capability. Menu library provides functionality to write menus from
3604which the user can chose more than one item as the preferred
3605choice. This is dealt with in a later section. Now it is time for
3606some rudiments.</p>
3607<div class="SECT2">
3608<hr>
3609<h3 class="SECT2"><a name="MENUBASICS" id="MENUBASICS">17.1. The
3610Basics</a></h3>
3611<p>To create menus, you first create items, and then post the menu
3612to the display. After that, all the processing of user responses is
3613done in an elegant function menu_driver() which is the work horse
3614of any menu program.</p>
3615<p>The general flow of control of a menu program looks like
3616this.</p>
3617<ol type="1">
3618<li>
3619<p>Initialize curses</p>
3620</li>
3621<li>
3622<p>Create items using new_item(). You can specify a name and
3623description for the items.</p>
3624</li>
3625<li>
3626<p>Create the menu with new_menu() by specifying the items to be
3627attached with.</p>
3628</li>
3629<li>
3630<p>Post the menu with menu_post() and refresh the screen.</p>
3631</li>
3632<li>
3633<p>Process the user requests with a loop and do necessary updates
3634to menu with menu_driver.</p>
3635</li>
3636<li>
3637<p>Unpost the menu with menu_unpost()</p>
3638</li>
3639<li>
3640<p>Free the memory allocated to menu by free_menu()</p>
3641</li>
3642<li>
3643<p>Free the memory allocated to the items with free_item()</p>
3644</li>
3645<li>
3646<p>End curses</p>
3647</li>
3648</ol>
3649<p>Let's see a program which prints a simple menu and updates the
3650current selection with up, down arrows.</p>
3651</div>
3652<div class="SECT2">
3653<hr>
3654<h3 class="SECT2"><a name="COMPILEMENUS" id="COMPILEMENUS">17.2.
3655Compiling With the Menu Library</a></h3>
3656<p>To use menu library functions, you have to include menu.h and to
3657link the program with menu library the flag -lmenu should be added
3658along with -lncurses in that order.</p>
3659<table border="0" bgcolor="#E0E0E0" width="100%">
3660<tr>
3661<td>
3662<pre class="PROGRAMLISTING">
3663<font color="#000000"> #include &lt;menu.h&gt;
3664 .
3665 .
3666 .
3667
3668 compile and link: gcc &lt;program file&gt; -lmenu -lncurses</font>
3669</pre></td>
3670</tr>
3671</table>
3672<div class="EXAMPLE"><a name="MMESI" id="MMESI"></a>
3673<p><b>Example 18. Menu Basics</b></p>
3674<table border="0" bgcolor="#E0E0E0" width="100%">
3675<tr>
3676<td>
3677<pre class="PROGRAMLISTING">
3678<font color="#000000"><span class=
3679"INLINEMEDIAOBJECT">#include &lt;curses.h&gt;
3680#include &lt;menu.h&gt;
3681
3682#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
3683#define CTRLD 4
3684
3685char *choices[] = {
3686 "Choice 1",
3687 "Choice 2",
3688 "Choice 3",
3689 "Choice 4",
3690 "Exit",
3691 };
3692
3693int main()
3694{ ITEM **my_items;
3695 int c;
3696 MENU *my_menu;
3697 int n_choices, i;
3698 ITEM *cur_item;
3699
3700
3701 initscr();
3702 cbreak();
3703 noecho();
3704 keypad(stdscr, TRUE);
3705
3706 n_choices = ARRAY_SIZE(choices);
3707 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
3708
3709 for(i = 0; i &lt; n_choices; ++i)
3710 my_items[i] = new_item(choices[i], choices[i]);
3711 my_items[n_choices] = (ITEM *)NULL;
3712
3713 my_menu = new_menu((ITEM **)my_items);
3714 mvprintw(LINES - 2, 0, "F1 to Exit");
3715 post_menu(my_menu);
3716 refresh();
3717
3718 while((c = getch()) != KEY_F(1))
3719 { switch(c)
3720 { case KEY_DOWN:
3721 menu_driver(my_menu, REQ_DOWN_ITEM);
3722 break;
3723 case KEY_UP:
3724 menu_driver(my_menu, REQ_UP_ITEM);
3725 break;
3726 }
3727 }
3728
3729 free_item(my_items[0]);
3730 free_item(my_items[1]);
3731 free_menu(my_menu);
3732 endwin();
3733}
3734 </span></font>
3735</pre></td>
3736</tr>
3737</table>
3738</div>
3739<p>This program demonstrates the basic concepts involved in
3740creating a menu using menus library. First we create the items
3741using new_item() and then attach them to the menu with new_menu()
3742function. After posting the menu and refreshing the screen, the
3743main processing loop starts. It reads user input and takes
3744corresponding action. The function menu_driver() is the main work
3745horse of the menu system. The second parameter to this function
3746tells what's to be done with the menu. According to the parameter,
3747menu_driver() does the corresponding task. The value can be either
3748a menu navigational request, an ascii character, or a KEY_MOUSE
3749special key associated with a mouse event.</p>
3750<p>The menu_driver accepts following navigational requests.</p>
3751<table border="0" bgcolor="#E0E0E0" width="100%">
3752<tr>
3753<td>
3754<pre class="PROGRAMLISTING">
3755<font color=
3756"#000000">&#13; REQ_LEFT_ITEM Move left to an item.
3757 REQ_RIGHT_ITEM Move right to an item.
3758 REQ_UP_ITEM Move up to an item.
3759 REQ_DOWN_ITEM Move down to an item.
3760 REQ_SCR_ULINE Scroll up a line.
3761 REQ_SCR_DLINE Scroll down a line.
3762 REQ_SCR_DPAGE Scroll down a page.
3763 REQ_SCR_UPAGE Scroll up a page.
3764 REQ_FIRST_ITEM Move to the first item.
3765 REQ_LAST_ITEM Move to the last item.
3766 REQ_NEXT_ITEM Move to the next item.
3767 REQ_PREV_ITEM Move to the previous item.
3768 REQ_TOGGLE_ITEM Select/deselect an item.
3769 REQ_CLEAR_PATTERN Clear the menu pattern buffer.
3770 REQ_BACK_PATTERN Delete the previous character from the pattern buffer.
3771 REQ_NEXT_MATCH Move to the next item matching the pattern match.
3772 REQ_PREV_MATCH Move to the previous item matching the pattern match.&#13;</font>
3773</pre></td>
3774</tr>
3775</table>
3776<p>Don't get overwhelmed by the number of options. We will see them
3777slowly one after another. The options of interest in this example
3778are REQ_UP_ITEM and REQ_DOWN_ITEM. These two options when passed to
3779menu_driver, menu driver updates the current item to one item up or
3780down respectively.</p>
3781</div>
3782<div class="SECT2">
3783<hr>
3784<h3 class="SECT2"><a name="MENUDRIVER" id="MENUDRIVER">17.3. Menu
3785Driver: The work horse of the menu system</a></h3>
3786<p>As you have seen in the above example, menu_driver plays an
3787important role in updating the menu. It is very important to
3788understand various options it takes and what they do. As explained
3789above, the second parameter to menu_driver() can be either a
3790navigational request, a printable character or a KEY_MOUSE key.
3791Let's dissect the different navigational requests.</p>
3792<ul>
3793<li>
3794<p><em>REQ_LEFT_ITEM and REQ_RIGHT_ITEM</em></p>
3795<p>A Menu can be displayed with multiple columns for more than one
3796item. This can be done by using the <var class=
3797"LITERAL">menu_format()</var>function. When a multi columnar menu
3798is displayed these requests cause the menu driver to move the
3799current selection to left or right.</p>
3800</li>
3801<li>
3802<p><em>REQ_UP_ITEM and REQ_DOWN_ITEM</em></p>
3803<p>These two options you have seen in the above example. These
3804options when given, makes the menu_driver to move the current
3805selection to an item up or down.</p>
3806</li>
3807<li>
3808<p><em>REQ_SCR_* options</em></p>
3809<p>The four options REQ_SCR_ULINE, REQ_SCR_DLINE, REQ_SCR_DPAGE,
3810REQ_SCR_UPAGE are related to scrolling. If all the items in the
3811menu cannot be displayed in the menu sub window, then the menu is
3812scrollable. These requests can be given to the menu_driver to do
3813the scrolling either one line up, down or one page down or up
3814respectively.</p>
3815</li>
3816<li>
3817<p><em>REQ_FIRST_ITEM, REQ_LAST_ITEM, REQ_NEXT_ITEM and
3818REQ_PREV_ITEM</em></p>
3819<p>These requests are self explanatory.</p>
3820</li>
3821<li>
3822<p><em>REQ_TOGGLE_ITEM</em></p>
3823<p>This request when given, toggles the present selection. This
3824option is to be used only in a multi valued menu. So to use this
3825request the option O_ONEVALUE must be off. This option can be made
3826off or on with set_menu_opts().</p>
3827</li>
3828<li>
3829<p><em>Pattern Requests</em></p>
3830<p>Every menu has an associated pattern buffer, which is used to
3831find the nearest match to the ascii characters entered by the user.
3832Whenever ascii characters are given to menu_driver, it puts in to
3833the pattern buffer. It also tries to find the nearest match to the
3834pattern in the items list and moves current selection to that item.
3835The request REQ_CLEAR_PATTERN clears the pattern buffer. The
3836request REQ_BACK_PATTERN deletes the previous character in the
3837pattern buffer. In case the pattern matches more than one item then
3838the matched items can be cycled through REQ_NEXT_MATCH and
3839REQ_PREV_MATCH which move the current selection to the next and
3840previous matches respectively.</p>
3841</li>
3842<li>
3843<p><em>Mouse Requests</em></p>
3844<p>In case of KEY_MOUSE requests, according to the mouse position
3845an action is taken accordingly. The action to be taken is explained
3846in the man page as,</p>
3847<table border="0" bgcolor="#E0E0E0" width="90%">
3848<tr>
3849<td>
3850<pre class="PROGRAMLISTING">
3851<font color=
3852"#000000"><em> If the second argument is the KEY_MOUSE special key, the
3853 associated mouse event is translated into one of the above
3854 pre-defined requests. Currently only clicks in the user
3855 window (e.g. inside the menu display area or the decora&shy;
3856 tion window) are handled. If you click above the display
3857 region of the menu, a REQ_SCR_ULINE is generated, if you
3858 doubleclick a REQ_SCR_UPAGE is generated and if you
3859 tripleclick a REQ_FIRST_ITEM is generated. If you click
3860 below the display region of the menu, a REQ_SCR_DLINE is
3861 generated, if you doubleclick a REQ_SCR_DPAGE is generated
3862 and if you tripleclick a REQ_LAST_ITEM is generated. If
3863 you click at an item inside the display area of the menu,
3864 the menu cursor is positioned to that item.</em></font>
3865</pre></td>
3866</tr>
3867</table>
3868</li>
3869</ul>
3870<p>Each of the above requests will be explained in the following
3871lines with several examples whenever appropriate.</p>
3872</div>
3873<div class="SECT2">
3874<hr>
3875<h3 class="SECT2"><a name="MENUWINDOWS" id="MENUWINDOWS">17.4. Menu
3876Windows</a></h3>
3877<p>Every menu created is associated with a window and a sub window.
3878The menu window displays any title or border associated with the
3879menu. The menu sub window displays the menu items currently
3880available for selection. But we didn't specify any window or sub
3881window in the simple example. When a window is not specified,
3882stdscr is taken as the main window, and then menu system calculates
3883the sub window size required for the display of items. Then items
3884are displayed in the calculated sub window. So let's play with
3885these windows and display a menu with a border and a title.</p>
3886<div class="EXAMPLE"><a name="MMEWI" id="MMEWI"></a>
3887<p><b>Example 19. Menu Windows Usage example</b></p>
3888<table border="0" bgcolor="#E0E0E0" width="100%">
3889<tr>
3890<td>
3891<pre class="PROGRAMLISTING">
3892<font color="#000000"><span class=
3893"INLINEMEDIAOBJECT">#include &lt;menu.h&gt;
3894
3895#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
3896#define CTRLD 4
3897
3898char *choices[] = {
3899 "Choice 1",
3900 "Choice 2",
3901 "Choice 3",
3902 "Choice 4",
3903 "Exit",
3904 (char *)NULL,
3905 };
3906void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
3907
3908int main()
3909{ ITEM **my_items;
3910 int c;
3911 MENU *my_menu;
3912 WINDOW *my_menu_win;
3913 int n_choices, i;
3914
3915 /* Initialize curses */
3916 initscr();
3917 start_color();
3918 cbreak();
3919 noecho();
3920 keypad(stdscr, TRUE);
3921 init_pair(1, COLOR_RED, COLOR_BLACK);
3922
3923 /* Create items */
3924 n_choices = ARRAY_SIZE(choices);
3925 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
3926 for(i = 0; i &lt; n_choices; ++i)
3927 my_items[i] = new_item(choices[i], choices[i]);
3928
3929 /* Crate menu */
3930 my_menu = new_menu((ITEM **)my_items);
3931
3932 /* Create the window to be associated with the menu */
3933 my_menu_win = newwin(10, 40, 4, 4);
3934 keypad(my_menu_win, TRUE);
3935
3936 /* Set main window and sub window */
3937 set_menu_win(my_menu, my_menu_win);
3938 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
3939
3940 /* Set menu mark to the string " * " */
3941 set_menu_mark(my_menu, " * ");
3942
3943 /* Print a border around the main window and print a title */
3944 box(my_menu_win, 0, 0);
3945 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
3946 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
3947 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
3948 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
3949 mvprintw(LINES - 2, 0, "F1 to exit");
3950 refresh();
3951
3952 /* Post the menu */
3953 post_menu(my_menu);
3954 wrefresh(my_menu_win);
3955
3956 while((c = wgetch(my_menu_win)) != KEY_F(1))
3957 { switch(c)
3958 { case KEY_DOWN:
3959 menu_driver(my_menu, REQ_DOWN_ITEM);
3960 break;
3961 case KEY_UP:
3962 menu_driver(my_menu, REQ_UP_ITEM);
3963 break;
3964 }
3965 wrefresh(my_menu_win);
3966 }
3967
3968 /* Unpost and free all the memory taken up */
3969 unpost_menu(my_menu);
3970 free_menu(my_menu);
3971 for(i = 0; i &lt; n_choices; ++i)
3972 free_item(my_items[i]);
3973 endwin();
3974}
3975
3976void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
3977{ int length, x, y;
3978 float temp;
3979
3980 if(win == NULL)
3981 win = stdscr;
3982 getyx(win, y, x);
3983 if(startx != 0)
3984 x = startx;
3985 if(starty != 0)
3986 y = starty;
3987 if(width == 0)
3988 width = 80;
3989
3990 length = strlen(string);
3991 temp = (width - length)/ 2;
3992 x = startx + (int)temp;
3993 wattron(win, color);
3994 mvwprintw(win, y, x, "%s", string);
3995 wattroff(win, color);
3996 refresh();
3997}</span></font>
3998</pre></td>
3999</tr>
4000</table>
4001</div>
4002<p>This example creates a menu with a title, border, a fancy line
4003separating title and the items. As you can see, in order to attach
4004a window to a menu the function set_menu_win() has to be used. Then
4005we attach the sub window also. This displays the items in the sub
4006window. You can also set the mark string which gets displayed to
4007the left of the selected item with set_menu_mark().</p>
4008</div>
4009<div class="SECT2">
4010<hr>
4011<h3 class="SECT2"><a name="SCROLLMENUS" id="SCROLLMENUS">17.5.
4012Scrolling Menus</a></h3>
4013<p>If the sub window given for a window is not big enough to show
4014all the items, then the menu will be scrollable. When you are on
4015the last item in the present list, if you send REQ_DOWN_ITEM, it
4016gets translated into REQ_SCR_DLINE and the menu scrolls by one
4017item. You can manually give REQ_SCR_ operations to do scrolling.
4018Let's see how it can be done.</p>
4019<div class="EXAMPLE"><a name="MMESC" id="MMESC"></a>
4020<p><b>Example 20. Scrolling Menus example</b></p>
4021<table border="0" bgcolor="#E0E0E0" width="100%">
4022<tr>
4023<td>
4024<pre class="PROGRAMLISTING">
4025<font color="#000000"><span class=
4026"INLINEMEDIAOBJECT">#include &lt;curses.h&gt;
4027#include &lt;menu.h&gt;
4028
4029#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4030#define CTRLD 4
4031
4032char *choices[] = {
4033 "Choice 1",
4034 "Choice 2",
4035 "Choice 3",
4036 "Choice 4",
4037 "Choice 5",
4038 "Choice 6",
4039 "Choice 7",
4040 "Choice 8",
4041 "Choice 9",
4042 "Choice 10",
4043 "Exit",
4044 (char *)NULL,
4045 };
4046void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
4047
4048int main()
4049{ ITEM **my_items;
4050 int c;
4051 MENU *my_menu;
4052 WINDOW *my_menu_win;
4053 int n_choices, i;
4054
4055 /* Initialize curses */
4056 initscr();
4057 start_color();
4058 cbreak();
4059 noecho();
4060 keypad(stdscr, TRUE);
4061 init_pair(1, COLOR_RED, COLOR_BLACK);
4062 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4063
4064 /* Create items */
4065 n_choices = ARRAY_SIZE(choices);
4066 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4067 for(i = 0; i &lt; n_choices; ++i)
4068 my_items[i] = new_item(choices[i], choices[i]);
4069
4070 /* Crate menu */
4071 my_menu = new_menu((ITEM **)my_items);
4072
4073 /* Create the window to be associated with the menu */
4074 my_menu_win = newwin(10, 40, 4, 4);
4075 keypad(my_menu_win, TRUE);
4076
4077 /* Set main window and sub window */
4078 set_menu_win(my_menu, my_menu_win);
4079 set_menu_sub(my_menu, derwin(my_menu_win, 6, 38, 3, 1));
4080 set_menu_format(my_menu, 5, 1);
4081
4082 /* Set menu mark to the string " * " */
4083 set_menu_mark(my_menu, " * ");
4084
4085 /* Print a border around the main window and print a title */
4086 box(my_menu_win, 0, 0);
4087 print_in_middle(my_menu_win, 1, 0, 40, "My Menu", COLOR_PAIR(1));
4088 mvwaddch(my_menu_win, 2, 0, ACS_LTEE);
4089 mvwhline(my_menu_win, 2, 1, ACS_HLINE, 38);
4090 mvwaddch(my_menu_win, 2, 39, ACS_RTEE);
4091
4092 /* Post the menu */
4093 post_menu(my_menu);
4094 wrefresh(my_menu_win);
4095
4096 attron(COLOR_PAIR(2));
4097 mvprintw(LINES - 2, 0, "Use PageUp and PageDown to scoll down or up a page of items");
4098 mvprintw(LINES - 1, 0, "Arrow Keys to navigate (F1 to Exit)");
4099 attroff(COLOR_PAIR(2));
4100 refresh();
4101
4102 while((c = wgetch(my_menu_win)) != KEY_F(1))
4103 { switch(c)
4104 { case KEY_DOWN:
4105 menu_driver(my_menu, REQ_DOWN_ITEM);
4106 break;
4107 case KEY_UP:
4108 menu_driver(my_menu, REQ_UP_ITEM);
4109 break;
4110 case KEY_NPAGE:
4111 menu_driver(my_menu, REQ_SCR_DPAGE);
4112 break;
4113 case KEY_PPAGE:
4114 menu_driver(my_menu, REQ_SCR_UPAGE);
4115 break;
4116 }
4117 wrefresh(my_menu_win);
4118 }
4119
4120 /* Unpost and free all the memory taken up */
4121 unpost_menu(my_menu);
4122 free_menu(my_menu);
4123 for(i = 0; i &lt; n_choices; ++i)
4124 free_item(my_items[i]);
4125 endwin();
4126}
4127
4128void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
4129{ int length, x, y;
4130 float temp;
4131
4132 if(win == NULL)
4133 win = stdscr;
4134 getyx(win, y, x);
4135 if(startx != 0)
4136 x = startx;
4137 if(starty != 0)
4138 y = starty;
4139 if(width == 0)
4140 width = 80;
4141
4142 length = strlen(string);
4143 temp = (width - length)/ 2;
4144 x = startx + (int)temp;
4145 wattron(win, color);
4146 mvwprintw(win, y, x, "%s", string);
4147 wattroff(win, color);
4148 refresh();
4149}</span></font>
4150</pre></td>
4151</tr>
4152</table>
4153</div>
4154<p>This program is self-explanatory. In this example the number of
4155choices has been increased to ten, which is larger than our sub
4156window size which can hold 6 items. This message has to be
4157explicitly conveyed to the menu system with the function
4158set_menu_format(). In here we specify the number of rows and
4159columns we want to be displayed for a single page. We can specify
4160any number of items to be shown, in the rows variables, if it is
4161less than the height of the sub window. If the key pressed by the
4162user is a PAGE UP or PAGE DOWN, the menu is scrolled a page due to
4163the requests (REQ_SCR_DPAGE and REQ_SCR_UPAGE) given to
4164menu_driver().</p>
4165</div>
4166<div class="SECT2">
4167<hr>
4168<h3 class="SECT2"><a name="MULTICOLUMN" id="MULTICOLUMN">17.6.
4169Multi Columnar Menus</a></h3>
4170<p>In the above example you have seen how to use the function
4171set_menu_format(). I didn't mention what the cols variable (third
4172parameter) does. Well, If your sub window is wide enough, you can
4173opt to display more than one item per row. This can be specified in
4174the cols variable. To make things simpler, the following example
4175doesn't show descriptions for the items.</p>
4176<div class="EXAMPLE"><a name="MMEMUCO" id="MMEMUCO"></a>
4177<p><b>Example 21. Milt Columnar Menus Example</b></p>
4178<table border="0" bgcolor="#E0E0E0" width="100%">
4179<tr>
4180<td>
4181<pre class="PROGRAMLISTING">
4182<font color="#000000"><span class=
4183"INLINEMEDIAOBJECT">#include &lt;curses.h&gt;
4184#include &lt;menu.h&gt;
4185
4186#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4187#define CTRLD 4
4188
4189char *choices[] = {
4190 "Choice 1", "Choice 2", "Choice 3", "Choice 4", "Choice 5",
4191 "Choice 6", "Choice 7", "Choice 8", "Choice 9", "Choice 10",
4192 "Choice 11", "Choice 12", "Choice 13", "Choice 14", "Choice 15",
4193 "Choice 16", "Choice 17", "Choice 18", "Choice 19", "Choice 20",
4194 "Exit",
4195 (char *)NULL,
4196 };
4197
4198int main()
4199{ ITEM **my_items;
4200 int c;
4201 MENU *my_menu;
4202 WINDOW *my_menu_win;
4203 int n_choices, i;
4204
4205 /* Initialize curses */
4206 initscr();
4207 start_color();
4208 cbreak();
4209 noecho();
4210 keypad(stdscr, TRUE);
4211 init_pair(1, COLOR_RED, COLOR_BLACK);
4212 init_pair(2, COLOR_CYAN, COLOR_BLACK);
4213
4214 /* Create items */
4215 n_choices = ARRAY_SIZE(choices);
4216 my_items = (ITEM **)calloc(n_choices, sizeof(ITEM *));
4217 for(i = 0; i &lt; n_choices; ++i)
4218 my_items[i] = new_item(choices[i], choices[i]);
4219
4220 /* Crate menu */
4221 my_menu = new_menu((ITEM **)my_items);
4222
4223 /* Set menu option not to show the description */
4224 menu_opts_off(my_menu, O_SHOWDESC);
4225
4226 /* Create the window to be associated with the menu */
4227 my_menu_win = newwin(10, 70, 4, 4);
4228 keypad(my_menu_win, TRUE);
4229
4230 /* Set main window and sub window */
4231 set_menu_win(my_menu, my_menu_win);
4232 set_menu_sub(my_menu, derwin(my_menu_win, 6, 68, 3, 1));
4233 set_menu_format(my_menu, 5, 3);
4234 set_menu_mark(my_menu, " * ");
4235
4236 /* Print a border around the main window and print a title */
4237 box(my_menu_win, 0, 0);
4238
4239 attron(COLOR_PAIR(2));
4240 mvprintw(LINES - 3, 0, "Use PageUp and PageDown to scroll");
4241 mvprintw(LINES - 2, 0, "Use Arrow Keys to navigate (F1 to Exit)");
4242 attroff(COLOR_PAIR(2));
4243 refresh();
4244
4245 /* Post the menu */
4246 post_menu(my_menu);
4247 wrefresh(my_menu_win);
4248
4249 while((c = wgetch(my_menu_win)) != KEY_F(1))
4250 { switch(c)
4251 { case KEY_DOWN:
4252 menu_driver(my_menu, REQ_DOWN_ITEM);
4253 break;
4254 case KEY_UP:
4255 menu_driver(my_menu, REQ_UP_ITEM);
4256 break;
4257 case KEY_LEFT:
4258 menu_driver(my_menu, REQ_LEFT_ITEM);
4259 break;
4260 case KEY_RIGHT:
4261 menu_driver(my_menu, REQ_RIGHT_ITEM);
4262 break;
4263 case KEY_NPAGE:
4264 menu_driver(my_menu, REQ_SCR_DPAGE);
4265 break;
4266 case KEY_PPAGE:
4267 menu_driver(my_menu, REQ_SCR_UPAGE);
4268 break;
4269 }
4270 wrefresh(my_menu_win);
4271 }
4272
4273 /* Unpost and free all the memory taken up */
4274 unpost_menu(my_menu);
4275 free_menu(my_menu);
4276 for(i = 0; i &lt; n_choices; ++i)
4277 free_item(my_items[i]);
4278 endwin();
4279}</span></font>
4280</pre></td>
4281</tr>
4282</table>
4283</div>
4284<p>Watch the function call to set_menu_format(). It specifies the
4285number of columns to be 3, thus displaying 3 items per row. We have
4286also switched off the showing descriptions with the function
4287menu_opts_off(). There are couple of functions set_menu_opts(),
4288menu_opts_on() and menu_opts() which can be used to manipulate menu
4289options. The following menu options can be specified.</p>
4290<table border="0" bgcolor="#E0E0E0" width="100%">
4291<tr>
4292<td>
4293<pre class="PROGRAMLISTING">
4294<font color="#000000"> O_ONEVALUE
4295 Only one item can be selected for this menu.
4296
4297 O_SHOWDESC
4298 Display the item descriptions when the menu is
4299 posted.
4300
4301 O_ROWMAJOR
4302 Display the menu in row-major order.
4303
4304 O_IGNORECASE
4305 Ignore the case when pattern-matching.
4306
4307 O_SHOWMATCH
4308 Move the cursor to within the item name while pat&shy;
4309 tern-matching.
4310
4311 O_NONCYCLIC
4312 Don't wrap around next-item and previous-item,
4313 requests to the other end of the menu.</font>
4314</pre></td>
4315</tr>
4316</table>
4317<p>All options are on by default. You can switch specific
4318attributes on or off with menu_opts_on() and menu_opts_off()
4319functions. You can also use set_menu_opts() to directly specify the
4320options. The argument to this function should be a OR ed value of
4321some of those above constants. The function menu_opts() can be used
4322to find out a menu's present options.</p>
4323</div>
4324<div class="SECT2">
4325<hr>
4326<h3 class="SECT2"><a name="MULTIVALUEMENUS" id=
4327"MULTIVALUEMENUS">17.7. Multi Valued Menus</a></h3>
4328<p>You might be wondering what if you switch off the option
4329O_ONEVALUE. Then the menu becomes multi-valued. That means you can
4330select more than one item. This brings us to the request
4331REQ_TOGGLE_ITEM. Let's see it in action.</p>
4332<div class="EXAMPLE"><a name="MMETO" id="MMETO"></a>
4333<p><b>Example 22. Multi Valued Menus example</b></p>
4334<table border="0" bgcolor="#E0E0E0" width="100%">
4335<tr>
4336<td>
4337<pre class="PROGRAMLISTING">
4338<font color="#000000"><span class=
4339"INLINEMEDIAOBJECT">#include &lt;curses.h&gt;
4340#include &lt;menu.h&gt;
4341
4342#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4343#define CTRLD 4
4344
4345char *choices[] = {
4346 "Choice 1",
4347 "Choice 2",
4348 "Choice 3",
4349 "Choice 4",
4350 "Choice 5",
4351 "Choice 6",
4352 "Choice 7",
4353 "Exit",
4354 };
4355
4356int main()
4357{ ITEM **my_items;
4358 int c;
4359 MENU *my_menu;
4360 int n_choices, i;
4361 ITEM *cur_item;
4362
4363 /* Initialize curses */
4364 initscr();
4365 cbreak();
4366 noecho();
4367 keypad(stdscr, TRUE);
4368
4369 /* Initialize items */
4370 n_choices = ARRAY_SIZE(choices);
4371 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4372 for(i = 0; i &lt; n_choices; ++i)
4373 my_items[i] = new_item(choices[i], choices[i]);
4374 my_items[n_choices] = (ITEM *)NULL;
4375
4376 my_menu = new_menu((ITEM **)my_items);
4377
4378 /* Make the menu multi valued */
4379 menu_opts_off(my_menu, O_ONEVALUE);
4380
4381 mvprintw(LINES - 3, 0, "Use &lt;SPACE&gt; to select or unselect an item.");
4382 mvprintw(LINES - 2, 0, "&lt;ENTER&gt; to see presently selected items(F1 to Exit)");
4383 post_menu(my_menu);
4384 refresh();
4385
4386 while((c = getch()) != KEY_F(1))
4387 { switch(c)
4388 { case KEY_DOWN:
4389 menu_driver(my_menu, REQ_DOWN_ITEM);
4390 break;
4391 case KEY_UP:
4392 menu_driver(my_menu, REQ_UP_ITEM);
4393 break;
4394 case ' ':
4395 menu_driver(my_menu, REQ_TOGGLE_ITEM);
4396 break;
4397 case 10: /* Enter */
4398 { char temp[200];
4399 ITEM **items;
4400
4401 items = menu_items(my_menu);
4402 temp[0] = '\0';
4403 for(i = 0; i &lt; item_count(my_menu); ++i)
4404 if(item_value(items[i]) == TRUE)
4405 { strcat(temp, item_name(items[i]));
4406 strcat(temp, " ");
4407 }
4408 move(20, 0);
4409 clrtoeol();
4410 mvprintw(20, 0, temp);
4411 refresh();
4412 }
4413 break;
4414 }
4415 }
4416
4417 free_item(my_items[0]);
4418 free_item(my_items[1]);
4419 free_menu(my_menu);
4420 endwin();
4421}
4422 </span></font>
4423</pre></td>
4424</tr>
4425</table>
4426</div>
4427<p>Whew, A lot of new functions. Let's take them one after another.
4428Firstly, the REQ_TOGGLE_ITEM. In a multi-valued menu, the user
4429should be allowed to select or un select more than one item. The
4430request REQ_TOGGLE_ITEM toggles the present selection. In this case
4431when space is pressed REQ_TOGGLE_ITEM request is sent to
4432menu_driver to achieve the result.</p>
4433<p>Now when the user presses &lt;ENTER&gt; we show the items he
4434presently selected. First we find out the items associated with the
4435menu using the function menu_items(). Then we loop through the
4436items to find out if the item is selected or not. The function
4437item_value() returns TRUE if an item is selected. The function
4438item_count() returns the number of items in the menu. The item name
4439can be found with item_name(). You can also find the description
4440associated with an item using item_description().</p>
4441</div>
4442<div class="SECT2">
4443<hr>
4444<h3 class="SECT2"><a name="MENUOPT" id="MENUOPT">17.8. Menu
4445Options</a></h3>
4446<p>Well, by this time you must be itching for some difference in
4447your menu, with lots of functionality. I know. You want Colors !!!.
4448You want to create nice menus similar to those text mode <a href=
4449"http://www.jersey.net/~debinjoe/games/" target="_top">dos
4450games</a>. The functions set_menu_fore() and set_menu_back() can be
4451used to change the attribute of the selected item and unselected
4452item. The names are misleading. They don't change menu's foreground
4453or background which would have been useless.</p>
4454<p>The function set_menu_grey() can be used to set the display
4455attribute for the non-selectable items in the menu. This brings us
4456to the interesting option for an item the one and only
4457O_SELECTABLE. We can turn it off by the function item_opts_off()
4458and after that that item is not selectable. It's like a grayed item
4459in those fancy windows menus. Let's put these concepts in practice
4460with this example</p>
4461<div class="EXAMPLE"><a name="MMEAT" id="MMEAT"></a>
4462<p><b>Example 23. Menu Options example</b></p>
4463<table border="0" bgcolor="#E0E0E0" width="100%">
4464<tr>
4465<td>
4466<pre class="PROGRAMLISTING">
4467<font color="#000000"><span class=
4468"INLINEMEDIAOBJECT">#include &lt;menu.h&gt;
4469
4470#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4471#define CTRLD 4
4472
4473char *choices[] = {
4474 "Choice 1",
4475 "Choice 2",
4476 "Choice 3",
4477 "Choice 4",
4478 "Choice 5",
4479 "Choice 6",
4480 "Choice 7",
4481 "Exit",
4482 };
4483
4484int main()
4485{ ITEM **my_items;
4486 int c;
4487 MENU *my_menu;
4488 int n_choices, i;
4489 ITEM *cur_item;
4490
4491 /* Initialize curses */
4492 initscr();
4493 start_color();
4494 cbreak();
4495 noecho();
4496 keypad(stdscr, TRUE);
4497 init_pair(1, COLOR_RED, COLOR_BLACK);
4498 init_pair(2, COLOR_GREEN, COLOR_BLACK);
4499 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
4500
4501 /* Initialize items */
4502 n_choices = ARRAY_SIZE(choices);
4503 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4504 for(i = 0; i &lt; n_choices; ++i)
4505 my_items[i] = new_item(choices[i], choices[i]);
4506 my_items[n_choices] = (ITEM *)NULL;
4507 item_opts_off(my_items[3], O_SELECTABLE);
4508 item_opts_off(my_items[6], O_SELECTABLE);
4509
4510 /* Create menu */
4511 my_menu = new_menu((ITEM **)my_items);
4512
4513 /* Set fore ground and back ground of the menu */
4514 set_menu_fore(my_menu, COLOR_PAIR(1) | A_REVERSE);
4515 set_menu_back(my_menu, COLOR_PAIR(2));
4516 set_menu_grey(my_menu, COLOR_PAIR(3));
4517
4518 /* Post the menu */
4519 mvprintw(LINES - 3, 0, "Press &lt;ENTER&gt; to see the option selected");
4520 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
4521 post_menu(my_menu);
4522 refresh();
4523
4524 while((c = getch()) != KEY_F(1))
4525 { switch(c)
4526 { case KEY_DOWN:
4527 menu_driver(my_menu, REQ_DOWN_ITEM);
4528 break;
4529 case KEY_UP:
4530 menu_driver(my_menu, REQ_UP_ITEM);
4531 break;
4532 case 10: /* Enter */
4533 move(20, 0);
4534 clrtoeol();
4535 mvprintw(20, 0, "Item selected is : %s",
4536 item_name(current_item(my_menu)));
4537 pos_menu_cursor(my_menu);
4538 break;
4539 }
4540 }
4541 unpost_menu(my_menu);
4542 for(i = 0; i &lt; n_choices; ++i)
4543 free_item(my_items[i]);
4544 free_menu(my_menu);
4545 endwin();
4546}
4547 </span></font>
4548</pre></td>
4549</tr>
4550</table>
4551</div>
4552</div>
4553<div class="SECT2">
4554<hr>
4555<h3 class="SECT2"><a name="MENUUSERPTR" id="MENUUSERPTR">17.9. The
4556useful User Pointer</a></h3>
4557<p>We can associate a user pointer with each item in the menu. It
4558works the same way as user pointer in panels. It's not touched by
4559menu system. You can store any thing you like in that. I usually
4560use it to store the function to be executed when the menu option is
4561chosen (It's selected and may be the user pressed
4562&lt;ENTER&gt;);</p>
4563<div class="EXAMPLE"><a name="MMEUS" id="MMEUS"></a>
4564<p><b>Example 24. Menu User Pointer Usage</b></p>
4565<table border="0" bgcolor="#E0E0E0" width="100%">
4566<tr>
4567<td>
4568<pre class="PROGRAMLISTING">
4569<font color="#000000"><span class=
4570"INLINEMEDIAOBJECT">#include &lt;curses.h&gt;
4571#include &lt;menu.h&gt;
4572
4573#define ARRAY_SIZE(a) (sizeof(a) / sizeof(a[0]))
4574#define CTRLD 4
4575
4576char *choices[] = {
4577 "Choice 1",
4578 "Choice 2",
4579 "Choice 3",
4580 "Choice 4",
4581 "Choice 5",
4582 "Choice 6",
4583 "Choice 7",
4584 "Exit",
4585 };
4586void func(char *name);
4587
4588int main()
4589{ ITEM **my_items;
4590 int c;
4591 MENU *my_menu;
4592 int n_choices, i;
4593 ITEM *cur_item;
4594
4595 /* Initialize curses */
4596 initscr();
4597 start_color();
4598 cbreak();
4599 noecho();
4600 keypad(stdscr, TRUE);
4601 init_pair(1, COLOR_RED, COLOR_BLACK);
4602 init_pair(2, COLOR_GREEN, COLOR_BLACK);
4603 init_pair(3, COLOR_MAGENTA, COLOR_BLACK);
4604
4605 /* Initialize items */
4606 n_choices = ARRAY_SIZE(choices);
4607 my_items = (ITEM **)calloc(n_choices + 1, sizeof(ITEM *));
4608 for(i = 0; i &lt; n_choices; ++i)
4609 { my_items[i] = new_item(choices[i], choices[i]);
4610 /* Set the user pointer */
4611 set_item_userptr(my_items[i], func);
4612 }
4613 my_items[n_choices] = (ITEM *)NULL;
4614
4615 /* Create menu */
4616 my_menu = new_menu((ITEM **)my_items);
4617
4618 /* Post the menu */
4619 mvprintw(LINES - 3, 0, "Press &lt;ENTER&gt; to see the option selected");
4620 mvprintw(LINES - 2, 0, "Up and Down arrow keys to naviage (F1 to Exit)");
4621 post_menu(my_menu);
4622 refresh();
4623
4624 while((c = getch()) != KEY_F(1))
4625 { switch(c)
4626 { case KEY_DOWN:
4627 menu_driver(my_menu, REQ_DOWN_ITEM);
4628 break;
4629 case KEY_UP:
4630 menu_driver(my_menu, REQ_UP_ITEM);
4631 break;
4632 case 10: /* Enter */
4633 { ITEM *cur;
4634 void (*p)(char *);
4635
4636 cur = current_item(my_menu);
4637 p = item_userptr(cur);
4638 p((char *)item_name(cur));
4639 pos_menu_cursor(my_menu);
4640 break;
4641 }
4642 break;
4643 }
4644 }
4645 unpost_menu(my_menu);
4646 for(i = 0; i &lt; n_choices; ++i)
4647 free_item(my_items[i]);
4648 free_menu(my_menu);
4649 endwin();
4650}
4651
4652void func(char *name)
4653{ move(20, 0);
4654 clrtoeol();
4655 mvprintw(20, 0, "Item selected is : %s", name);
4656} </span></font>
4657</pre></td>
4658</tr>
4659</table>
4660</div>
4661</div>
4662</div>
4663<div class="SECT1">
4664<hr>
4665<h2 class="SECT1"><a name="FORMS" id="FORMS">18. Forms
4666Library</a></h2>
4667<p>Well. If you have seen those forms on web pages which take input
4668from users and do various kinds of things, you might be wondering
4669how would any one create such forms in text mode display. It's
4670quite difficult to write those nifty forms in plain ncurses. Forms
4671library tries to provide a basic frame work to build and maintain
4672forms with ease. It has lot of features(functions) which manage
4673validation, dynamic expansion of fields etc.. Let's see it in full
4674flow.</p>
4675<p>A form is a collection of fields; each field can be either a
4676label(static text) or a data-entry location. The forms also library
4677provides functions to divide forms into multiple pages.</p>
4678<div class="SECT2">
4679<hr>
4680<h3 class="SECT2"><a name="FORMBASICS" id="FORMBASICS">18.1. The
4681Basics</a></h3>
4682<p>Forms are created in much the same way as menus. First the
4683fields related to the form are created with new_field(). You can
4684set options for the fields, so that they can be displayed with some
4685fancy attributes, validated before the field looses focus etc..
4686Then the fields are attached to form. After this, the form can be
4687posted to display and is ready to receive inputs. On the similar
4688lines to menu_driver(), the form is manipulated with form_driver().
4689We can send requests to form_driver to move focus to a certain
4690field, move cursor to end of the field etc.. After the user enters
4691values in the fields and validation done, form can be unposted and
4692memory allocated can be freed.</p>
4693<p>The general flow of control of a forms program looks like
4694this.</p>
4695<ol type="1">
4696<li>
4697<p>Initialize curses</p>
4698</li>
4699<li>
4700<p>Create fields using new_field(). You can specify the height and
4701width of the field, and its position on the form.</p>
4702</li>
4703<li>
4704<p>Create the forms with new_form() by specifying the fields to be
4705attached with.</p>
4706</li>
4707<li>
4708<p>Post the form with form_post() and refresh the screen.</p>
4709</li>
4710<li>
4711<p>Process the user requests with a loop and do necessary updates
4712to form with form_driver.</p>
4713</li>
4714<li>
4715<p>Unpost the menu with form_unpost()</p>
4716</li>
4717<li>
4718<p>Free the memory allocated to menu by free_form()</p>
4719</li>
4720<li>
4721<p>Free the memory allocated to the items with free_field()</p>
4722</li>
4723<li>
4724<p>End curses</p>
4725</li>
4726</ol>
4727<p>As you can see, working with forms library is much similar to
4728handling menu library. The following examples will explore various
4729aspects of form processing. Let's start the journey with a simple
4730example. first.</p>
4731</div>
4732<div class="SECT2">
4733<hr>
4734<h3 class="SECT2"><a name="COMPILEFORMS" id="COMPILEFORMS">18.2.
4735Compiling With the Forms Library</a></h3>
4736<p>To use forms library functions, you have to include form.h and
4737to link the program with forms library the flag -lform should be
4738added along with -lncurses in that order.</p>
4739<table border="0" bgcolor="#E0E0E0" width="100%">
4740<tr>
4741<td>
4742<pre class="PROGRAMLISTING">
4743<font color="#000000"> #include &lt;form.h&gt;
4744 .
4745 .
4746 .
4747
4748 compile and link: gcc &lt;program file&gt; -lform -lncurses</font>
4749</pre></td>
4750</tr>
4751</table>
4752<div class="EXAMPLE"><a name="FFOSI" id="FFOSI"></a>
4753<p><b>Example 25. Forms Basics</b></p>
4754<table border="0" bgcolor="#E0E0E0" width="100%">
4755<tr>
4756<td>
4757<pre class="PROGRAMLISTING">
4758<font color="#000000"><span class=
4759"INLINEMEDIAOBJECT">#include &lt;form.h&gt;
4760
4761int main()
4762{ FIELD *field[3];
4763 FORM *my_form;
4764 int ch;
4765
4766 /* Initialize curses */
4767 initscr();
4768 cbreak();
4769 noecho();
4770 keypad(stdscr, TRUE);
4771
4772 /* Initialize the fields */
4773 field[0] = new_field(1, 10, 4, 18, 0, 0);
4774 field[1] = new_field(1, 10, 6, 18, 0, 0);
4775 field[2] = NULL;
4776
4777 /* Set field options */
4778 set_field_back(field[0], A_UNDERLINE); /* Print a line for the option */
4779 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
4780 /* Field is filled up */
4781 set_field_back(field[1], A_UNDERLINE);
4782 field_opts_off(field[1], O_AUTOSKIP);
4783
4784 /* Create the form and post it */
4785 my_form = new_form(field);
4786 post_form(my_form);
4787 refresh();
4788
4789 mvprintw(4, 10, "Value 1:");
4790 mvprintw(6, 10, "Value 2:");
4791 refresh();
4792
4793 /* Loop through to get user requests */
4794 while((ch = getch()) != KEY_F(1))
4795 { switch(ch)
4796 { case KEY_DOWN:
4797 /* Go to next field */
4798 form_driver(my_form, REQ_NEXT_FIELD);
4799 /* Go to the end of the present buffer */
4800 /* Leaves nicely at the last character */
4801 form_driver(my_form, REQ_END_LINE);
4802 break;
4803 case KEY_UP:
4804 /* Go to previous field */
4805 form_driver(my_form, REQ_PREV_FIELD);
4806 form_driver(my_form, REQ_END_LINE);
4807 break;
4808 default:
4809 /* If this is a normal character, it gets */
4810 /* Printed */
4811 form_driver(my_form, ch);
4812 break;
4813 }
4814 }
4815
4816 /* Un post form and free the memory */
4817 unpost_form(my_form);
4818 free_form(my_form);
4819 free_field(field[0]);
4820 free_field(field[1]);
4821
4822 endwin();
4823 return 0;
4824}</span></font>
4825</pre></td>
4826</tr>
4827</table>
4828</div>
4829<p>Above example is pretty straight forward. It creates two fields
4830with <var class="LITERAL">new_field()</var>. new_field() takes
4831height, width, starty, startx, number of offscreen rows and number
4832of additional working buffers. The fifth argument number of
4833offscreen rows specifies how much of the field to be shown. If it
4834is zero, the entire field is always displayed otherwise the form
4835will be scrollable when the user accesses not displayed parts of
4836the field. The forms library allocates one buffer per field to
4837store the data user enters. Using the last parameter to new_field()
4838we can specify it to allocate some additional buffers. These can be
4839used for any purpose you like.</p>
4840<p>After creating the fields, back ground attribute of both of them
4841is set to an underscore with set_field_back(). The AUTOSKIP option
4842is turned off using field_opts_off(). If this option is turned on,
4843focus will move to the next field in the form once the active field
4844is filled up completely.</p>
4845<p>After attaching the fields to the form, it is posted. Here on,
4846user inputs are processed in the while loop, by making
4847corresponding requests to form_driver. The details of all the
4848requests to the form_driver() are explained later.</p>
4849</div>
4850<div class="SECT2">
4851<hr>
4852<h3 class="SECT2"><a name="PLAYFIELDS" id="PLAYFIELDS">18.3.
4853Playing with Fields</a></h3>
4854<p>Each form field is associated with a lot of attributes. They can
4855be manipulated to get the required effect and to have fun !!!. So
4856why wait?</p>
4857<div class="SECT3">
4858<hr>
4859<h4 class="SECT3"><a name="FETCHINFO" id="FETCHINFO">18.3.1.
4860Fetching Size and Location of Field</a></h4>
4861<p>The parameters we have given at the time of creation of a field
4862can be retrieved with field_info(). It returns height, width,
4863starty, startx, number of offscreen rows, and number of additional
4864buffers into the parameters given to it. It is a sort of inverse of
4865new_field().</p>
4866<table border="0" bgcolor="#E0E0E0" width="100%">
4867<tr>
4868<td>
4869<pre class="PROGRAMLISTING">
4870<font color=
4871"#000000">int field_info( FIELD *field, /* field from which to fetch */
4872 int *height, *int width, /* field size */
4873 int *top, int *left, /* upper left corner */
4874 int *offscreen, /* number of offscreen rows */
4875 int *nbuf); /* number of working buffers */</font>
4876</pre></td>
4877</tr>
4878</table>
4879</div>
4880<div class="SECT3">
4881<hr>
4882<h4 class="SECT3"><a name="MOVEFIELD" id="MOVEFIELD">18.3.2. Moving
4883the field</a></h4>
4884<p>The location of the field can be moved to a different position
4885with move_field().</p>
4886<table border="0" bgcolor="#E0E0E0" width="100%">
4887<tr>
4888<td>
4889<pre class="PROGRAMLISTING">
4890<font color=
4891"#000000">int move_field( FIELD *field, /* field to alter */
4892 int top, int left); /* new upper-left corner */</font>
4893</pre></td>
4894</tr>
4895</table>
4896<p>As usual, the changed position can be queried with
4897field_infor().</p>
4898</div>
4899<div class="SECT3">
4900<hr>
4901<h4 class="SECT3"><a name="JUSTIFYFIELD" id="JUSTIFYFIELD">18.3.3.
4902Field Justification</a></h4>
4903<p>The justification to be done for the field can be fixed using
4904the function set_field_just().</p>
4905<table border="0" bgcolor="#E0E0E0" width="100%">
4906<tr>
4907<td>
4908<pre class="PROGRAMLISTING">
4909<font color=
4910"#000000"> int set_field_just(FIELD *field, /* field to alter */
4911 int justmode); /* mode to set */
4912 int field_just(FIELD *field); /* fetch justify mode of field */</font>
4913</pre></td>
4914</tr>
4915</table>
4916<p>The justification mode valued accepted and returned by these
4917functions are NO_JUSTIFICATION, JUSTIFY_RIGHT, JUSTIFY_LEFT, or
4918JUSTIFY_CENTER.</p>
4919</div>
4920<div class="SECT3">
4921<hr>
4922<h4 class="SECT3"><a name="FIELDDISPATTRIB" id=
4923"FIELDDISPATTRIB">18.3.4. Field Display Attributes</a></h4>
4924<p>As you have seen, in the above example, display attribute for
4925the fields can be set with set_field_fore() and setfield_back().
4926These functions set foreground and background attribute of the
4927fields. You can also specify a pad character which will be filled
4928in the unfilled portion of the field. The pad character is set with
4929a call to set_field_pad(). Default pad value is a space. The
4930functions field_fore(), field_back, field_pad() can be used to
4931query the present foreground, background attributes and pad
4932character for the field. The following list gives the usage of
4933functions.</p>
4934<table border="0" bgcolor="#E0E0E0" width="100%">
4935<tr>
4936<td>
4937<pre class="PROGRAMLISTING">
4938<font color=
4939"#000000">&#13;int set_field_fore(FIELD *field, /* field to alter */
4940 chtype attr); /* attribute to set */
4941
4942chtype field_fore(FIELD *field); /* field to query */
4943 /* returns foreground attribute */
4944
4945int set_field_back(FIELD *field, /* field to alter */
4946 chtype attr); /* attribute to set */
4947
4948chtype field_back(FIELD *field); /* field to query */
4949 /* returns background attribute */
4950
4951int set_field_pad(FIELD *field, /* field to alter */
4952 int pad); /* pad character to set */
4953
4954chtype field_pad(FIELD *field); /* field to query */
4955 /* returns present pad character */&#13;</font>
4956</pre></td>
4957</tr>
4958</table>
4959<p>Though above functions seem quite simple, using colors with
4960set_field_fore() may be frustrating in the beginning. Let me first
4961explain about foreground and background attributes of a field. The
4962foreground attribute is associated with the character. That means a
4963character in the field is printed with the attribute you have set
4964with set_field_fore(). Background attribute is the attribute used
4965to fill background of field, whether any character is there or not.
4966So what about colors? Since colors are always defined in pairs,
4967what is the right way to display colored fields? Here's an example
4968clarifying color attributes.</p>
4969<div class="EXAMPLE"><a name="FFOAT" id="FFOAT"></a>
4970<p><b>Example 26. Form Attributes example</b></p>
4971<table border="0" bgcolor="#E0E0E0" width="100%">
4972<tr>
4973<td>
4974<pre class="PROGRAMLISTING">
4975<font color="#000000"><span class=
4976"INLINEMEDIAOBJECT">#include &lt;form.h&gt;
4977
4978int main()
4979{ FIELD *field[3];
4980 FORM *my_form;
4981 int ch;
4982
4983 /* Initialize curses */
4984 initscr();
4985 start_color();
4986 cbreak();
4987 noecho();
4988 keypad(stdscr, TRUE);
4989
4990 /* Initialize few color pairs */
4991 init_pair(1, COLOR_WHITE, COLOR_BLUE);
4992 init_pair(2, COLOR_WHITE, COLOR_BLUE);
4993
4994 /* Initialize the fields */
4995 field[0] = new_field(1, 10, 4, 18, 0, 0);
4996 field[1] = new_field(1, 10, 6, 18, 0, 0);
4997 field[2] = NULL;
4998
4999 /* Set field options */
5000 set_field_fore(field[0], COLOR_PAIR(1));/* Put the field with blue background */
5001 set_field_back(field[0], COLOR_PAIR(2));/* and white foreground (characters */
5002 /* are printed in white */
5003 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5004 /* Field is filled up */
5005 set_field_back(field[1], A_UNDERLINE);
5006 field_opts_off(field[1], O_AUTOSKIP);
5007
5008 /* Create the form and post it */
5009 my_form = new_form(field);
5010 post_form(my_form);
5011 refresh();
5012
5013 set_current_field(my_form, field[0]); /* Set focus to the colored field */
5014 mvprintw(4, 10, "Value 1:");
5015 mvprintw(6, 10, "Value 2:");
5016 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5017 refresh();
5018
5019 /* Loop through to get user requests */
5020 while((ch = getch()) != KEY_F(1))
5021 { switch(ch)
5022 { case KEY_DOWN:
5023 /* Go to next field */
5024 form_driver(my_form, REQ_NEXT_FIELD);
5025 /* Go to the end of the present buffer */
5026 /* Leaves nicely at the last character */
5027 form_driver(my_form, REQ_END_LINE);
5028 break;
5029 case KEY_UP:
5030 /* Go to previous field */
5031 form_driver(my_form, REQ_PREV_FIELD);
5032 form_driver(my_form, REQ_END_LINE);
5033 break;
5034 default:
5035 /* If this is a normal character, it gets */
5036 /* Printed */
5037 form_driver(my_form, ch);
5038 break;
5039 }
5040 }
5041
5042 /* Un post form and free the memory */
5043 unpost_form(my_form);
5044 free_form(my_form);
5045 free_field(field[0]);
5046 free_field(field[1]);
5047
5048 endwin();
5049 return 0;
5050}</span></font>
5051</pre></td>
5052</tr>
5053</table>
5054</div>
5055<p>Play with the color pairs and try to understand the foreground
5056and background attributes. In my programs using color attributes, I
5057usually set only the background with set_field_back(). Curses
5058simply doesn't allow defining individual color attributes.</p>
5059</div>
5060<div class="SECT3">
5061<hr>
5062<h4 class="SECT3"><a name="FIELDOPTIONBITS" id=
5063"FIELDOPTIONBITS">18.3.5. Field Option Bits</a></h4>
5064<p>There is also a large collection of field option bits you can
5065set to control various aspects of forms processing. You can
5066manipulate them with these functions:</p>
5067<table border="0" bgcolor="#E0E0E0" width="100%">
5068<tr>
5069<td>
5070<pre class="PROGRAMLISTING">
5071<font color=
5072"#000000">int set_field_opts(FIELD *field, /* field to alter */
5073 int attr); /* attribute to set */
5074
5075int field_opts_on(FIELD *field, /* field to alter */
5076 int attr); /* attributes to turn on */
5077
5078int field_opts_off(FIELD *field, /* field to alter */
5079 int attr); /* attributes to turn off */
5080
5081int field_opts(FIELD *field); /* field to query */ </font>
5082</pre></td>
5083</tr>
5084</table>
5085<p>The function set_field_opts() can be used to directly set
5086attributes of a field or you can choose to switch a few attributes
5087on and off with field_opts_on() and field_opts_off() selectively.
5088Anytime you can query the attributes of a field with field_opts().
5089The following is the list of available options. By default, all
5090options are on.</p>
5091<div class="VARIABLELIST">
5092<dl>
5093<dt>O_VISIBLE</dt>
5094<dd>
5095<p>Controls whether the field is visible on the screen. Can be used
5096during form processing to hide or pop up fields depending on the
5097value of parent fields.</p>
5098</dd>
5099<dt>O_ACTIVE</dt>
5100<dd>
5101<p>Controls whether the field is active during forms processing
5102(i.e. visited by form navigation keys). Can be used to make labels
5103or derived fields with buffer values alterable by the forms
5104application, not the user.</p>
5105</dd>
5106<dt>O_PUBLIC</dt>
5107<dd>
5108<p>Controls whether data is displayed during field entry. If this
5109option is turned off on a field, the library will accept and edit
5110data in that field, but it will not be displayed and the visible
5111field cursor will not move. You can turn off the O_PUBLIC bit to
5112define password fields.</p>
5113</dd>
5114<dt>O_EDIT</dt>
5115<dd>
5116<p>Controls whether the field's data can be modified. When this
5117option is off, all editing requests except <var class=
5118"LITERAL">REQ_PREV_CHOICE</var> and <var class=
5119"LITERAL">REQ_NEXT_CHOICE</var>will fail. Such read-only fields may
5120be useful for help messages.</p>
5121</dd>
5122<dt>O_WRAP</dt>
5123<dd>
5124<p>Controls word-wrapping in multi-line fields. Normally, when any
5125character of a (blank-separated) word reaches the end of the
5126current line, the entire word is wrapped to the next line (assuming
5127there is one). When this option is off, the word will be split
5128across the line break.</p>
5129</dd>
5130<dt>O_BLANK</dt>
5131<dd>
5132<p>Controls field blanking. When this option is on, entering a
5133character at the first field position erases the entire field
5134(except for the just-entered character).</p>
5135</dd>
5136<dt>O_AUTOSKIP</dt>
5137<dd>
5138<p>Controls automatic skip to next field when this one fills.
5139Normally, when the forms user tries to type more data into a field
5140than will fit, the editing location jumps to next field. When this
5141option is off, the user's cursor will hang at the end of the field.
5142This option is ignored in dynamic fields that have not reached
5143their size limit.</p>
5144</dd>
5145<dt>O_NULLOK</dt>
5146<dd>
5147<p>Controls whether validation is applied to blank fields.
5148Normally, it is not; the user can leave a field blank without
5149invoking the usual validation check on exit. If this option is off
5150on a field, exit from it will invoke a validation check.</p>
5151</dd>
5152<dt>O_PASSOK</dt>
5153<dd>
5154<p>Controls whether validation occurs on every exit, or only after
5155the field is modified. Normally the latter is true. Setting
5156O_PASSOK may be useful if your field's validation function may
5157change during forms processing.</p>
5158</dd>
5159<dt>O_STATIC</dt>
5160<dd>
5161<p>Controls whether the field is fixed to its initial dimensions.
5162If you turn this off, the field becomes dynamic and will stretch to
5163fit entered data.</p>
5164</dd>
5165</dl>
5166</div>
5167<p>A field's options cannot be changed while the field is currently
5168selected. However, options may be changed on posted fields that are
5169not current.</p>
5170<p>The option values are bit-masks and can be composed with
5171logical-or in the obvious way. You have seen the usage of switching
5172off O_AUTOSKIP option. The following example clarifies usage of
5173some more options. Other options are explained where
5174appropriate.</p>
5175<div class="EXAMPLE"><a name="FFOOP" id="FFOOP"></a>
5176<p><b>Example 27. Field Options Usage example</b></p>
5177<table border="0" bgcolor="#E0E0E0" width="100%">
5178<tr>
5179<td>
5180<pre class="PROGRAMLISTING">
5181<font color="#000000"><span class=
5182"INLINEMEDIAOBJECT">#include &lt;form.h&gt;
5183
5184#define STARTX 15
5185#define STARTY 4
5186#define WIDTH 25
5187
5188#define N_FIELDS 3
5189
5190int main()
5191{ FIELD *field[N_FIELDS];
5192 FORM *my_form;
5193 int ch, i;
5194
5195 /* Initialize curses */
5196 initscr();
5197 cbreak();
5198 noecho();
5199 keypad(stdscr, TRUE);
5200
5201 /* Initialize the fields */
5202 for(i = 0; i &lt; N_FIELDS - 1; ++i)
5203 field[i] = new_field(1, WIDTH, STARTY + i * 2, STARTX, 0, 0);
5204 field[N_FIELDS - 1] = NULL;
5205
5206 /* Set field options */
5207 set_field_back(field[1], A_UNDERLINE); /* Print a line for the option */
5208
5209 field_opts_off(field[0], O_ACTIVE); /* This field is a static label */
5210 field_opts_off(field[1], O_PUBLIC); /* This filed is like a password field*/
5211 field_opts_off(field[1], O_AUTOSKIP); /* To avoid entering the same field */
5212 /* after last character is entered */
5213
5214 /* Create the form and post it */
5215 my_form = new_form(field);
5216 post_form(my_form);
5217 refresh();
5218
5219 set_field_just(field[0], JUSTIFY_CENTER); /* Center Justification */
5220 set_field_buffer(field[0], 0, "This is a static Field");
5221 /* Initialize the field */
5222 mvprintw(STARTY, STARTX - 10, "Field 1:");
5223 mvprintw(STARTY + 2, STARTX - 10, "Field 2:");
5224 refresh();
5225
5226 /* Loop through to get user requests */
5227 while((ch = getch()) != KEY_F(1))
5228 { switch(ch)
5229 { case KEY_DOWN:
5230 /* Go to next field */
5231 form_driver(my_form, REQ_NEXT_FIELD);
5232 /* Go to the end of the present buffer */
5233 /* Leaves nicely at the last character */
5234 form_driver(my_form, REQ_END_LINE);
5235 break;
5236 case KEY_UP:
5237 /* Go to previous field */
5238 form_driver(my_form, REQ_PREV_FIELD);
5239 form_driver(my_form, REQ_END_LINE);
5240 break;
5241 default:
5242 /* If this is a normal character, it gets */
5243 /* Printed */
5244 form_driver(my_form, ch);
5245 break;
5246 }
5247 }
5248
5249 /* Un post form and free the memory */
5250 unpost_form(my_form);
5251 free_form(my_form);
5252 free_field(field[0]);
5253 free_field(field[1]);
5254
5255 endwin();
5256 return 0;
5257}</span></font>
5258</pre></td>
5259</tr>
5260</table>
5261</div>
5262<p>This example, though useless, shows the usage of options. If
5263used properly, they can present information very effectively in a
5264form. The second field being not O_PUBLIC, does not show the
5265characters you are typing.</p>
5266</div>
5267<div class="SECT3">
5268<hr>
5269<h4 class="SECT3"><a name="FIELDSTATUS" id="FIELDSTATUS">18.3.6.
5270Field Status</a></h4>
5271<p>The field status specifies whether the field has got edited or
5272not. It is initially set to FALSE and when user enters something
5273and the data buffer gets modified it becomes TRUE. So a field's
5274status can be queried to find out whether it has been modified or
5275not. The following functions can assist in those operations.</p>
5276<table border="0" bgcolor="#E0E0E0" width="100%">
5277<tr>
5278<td>
5279<pre class="PROGRAMLISTING">
5280<font color=
5281"#000000">int set_field_status(FIELD *field, /* field to alter */
5282 int status); /* status to set */
5283
5284int field_status(FIELD *field); /* fetch status of field */</font>
5285</pre></td>
5286</tr>
5287</table>
5288<p>It's better to check the field's status only after after leaving
5289the field, as data buffer might not have been updated yet as the
5290validation is still due. To guarantee that right status is
5291returned, call field_status() either (1) in the field's exit
5292validation check routine, (2) from the field's or form's
5293initialization or termination hooks, or (3) just after a
5294REQ_VALIDATION request has been processed by the forms driver</p>
5295</div>
5296<div class="SECT3">
5297<hr>
5298<h4 class="SECT3"><a name="FIELDUSERPTR" id="FIELDUSERPTR">18.3.7.
5299Field User Pointer</a></h4>
5300<p>Every field structure contains one pointer that can be used by
5301the user for various purposes. It is not touched by forms library
5302and can be used for any purpose by the user. The following
5303functions set and fetch user pointer.</p>
5304<table border="0" bgcolor="#E0E0E0" width="100%">
5305<tr>
5306<td>
5307<pre class="PROGRAMLISTING">
5308<font color="#000000">int set_field_userptr(FIELD *field,
5309 char *userptr); /* the user pointer you wish to associate */
5310 /* with the field */
5311
5312char *field_userptr(FIELD *field); /* fetch user pointer of the field */</font>
5313</pre></td>
5314</tr>
5315</table>
5316</div>
5317<div class="SECT3">
5318<hr>
5319<h4 class="SECT3"><a name="VARIABLESIZEFIELDS" id=
5320"VARIABLESIZEFIELDS">18.3.8. Variable-Sized Fields</a></h4>
5321<p>If you want a dynamically changing field with variable width,
5322this is the feature you want to put to full use. This will allow
5323the user to enter more data than the original size of the field and
5324let the field grow. According to the field orientation it will
5325scroll horizontally or vertically to incorporate the new data.</p>
5326<p>To make a field dynamically growable, the option O_STATIC should
5327be turned off. This can be done with a</p>
5328<table border="0" bgcolor="#E0E0E0" width="100%">
5329<tr>
5330<td>
5331<pre class="PROGRAMLISTING">
5332<font color=
5333"#000000"> field_opts_off(field_pointer, O_STATIC);</font>
5334</pre></td>
5335</tr>
5336</table>
5337<p>But it's usually not advisable to allow a field to grow
5338infinitely. You can set a maximum limit to the growth of the field
5339with</p>
5340<table border="0" bgcolor="#E0E0E0" width="100%">
5341<tr>
5342<td>
5343<pre class="PROGRAMLISTING">
5344<font color=
5345"#000000">int set_max_field(FIELD *field, /* Field on which to operate */
5346 int max_growth); /* maximum growth allowed for the field */</font>
5347</pre></td>
5348</tr>
5349</table>
5350<p>The field info for a dynamically growable field can be retrieved
5351by</p>
5352<table border="0" bgcolor="#E0E0E0" width="100%">
5353<tr>
5354<td>
5355<pre class="PROGRAMLISTING">
5356<font color=
5357"#000000">int dynamic_field_info( FIELD *field, /* Field on which to operate */
5358 int *prows, /* number of rows will be filled in this */
5359 int *pcols, /* number of columns will be filled in this*/
5360 int *pmax) /* maximum allowable growth will be filled */
5361 /* in this */</font>
5362</pre></td>
5363</tr>
5364</table>
5365Though field_info work as usual, it is advisable to use this
5366function to get the proper attributes of a dynamically growable
5367field.
5368<p>Recall the library routine new_field; a new field created with
5369height set to one will be defined to be a one line field. A new
5370field created with height greater than one will be defined to be a
5371multi line field.</p>
5372<p>A one line field with O_STATIC turned off (dynamically growable
5373field) will contain a single fixed row, but the number of columns
5374can increase if the user enters more data than the initial field
5375will hold. The number of columns displayed will remain fixed and
5376the additional data will scroll horizontally.</p>
5377<p>A multi line field with O_STATIC turned off (dynamically
5378growable field) will contain a fixed number of columns, but the
5379number of rows can increase if the user enters more data than the
5380initial field will hold. The number of rows displayed will remain
5381fixed and the additional data will scroll vertically.</p>
5382<p>The above two paragraphs pretty much describe a dynamically
5383growable field's behavior. The way other parts of forms library
5384behaves is described below:</p>
5385<ol type="1">
5386<li>
5387<p>The field option O_AUTOSKIP will be ignored if the option
5388O_STATIC is off and there is no maximum growth specified for the
5389field. Currently, O_AUTOSKIP generates an automatic REQ_NEXT_FIELD
5390form driver request when the user types in the last character
5391position of a field. On a growable field with no maximum growth
5392specified, there is no last character position. If a maximum growth
5393is specified, the O_AUTOSKIP option will work as normal if the
5394field has grown to its maximum size.</p>
5395</li>
5396<li>
5397<p>The field justification will be ignored if the option O_STATIC
5398is off. Currently, set_field_just can be used to JUSTIFY_LEFT,
5399JUSTIFY_RIGHT, JUSTIFY_CENTER the contents of a one line field. A
5400growable one line field will, by definition, grow and scroll
5401horizontally and may contain more data than can be justified. The
5402return from field_just will be unchanged.</p>
5403</li>
5404<li>
5405<p>The overloaded form driver request REQ_NEW_LINE will operate the
5406same way regardless of the O_NL_OVERLOAD form option if the field
5407option O_STATIC is off and there is no maximum growth specified for
5408the field. Currently, if the form option O_NL_OVERLOAD is on,
5409REQ_NEW_LINE implicitly generates a REQ_NEXT_FIELD if called from
5410the last line of a field. If a field can grow without bound, there
5411is no last line, so REQ_NEW_LINE will never implicitly generate a
5412REQ_NEXT_FIELD. If a maximum growth limit is specified and the
5413O_NL_OVERLOAD form option is on, REQ_NEW_LINE will only implicitly
5414generate REQ_NEXT_FIELD if the field has grown to its maximum size
5415and the user is on the last line.</p>
5416</li>
5417<li>
5418<p>The library call dup_field will work as usual; it will duplicate
5419the field, including the current buffer size and contents of the
5420field being duplicated. Any specified maximum growth will also be
5421duplicated.</p>
5422</li>
5423<li>
5424<p>The library call link_field will work as usual; it will
5425duplicate all field attributes and share buffers with the field
5426being linked. If the O_STATIC field option is subsequently changed
5427by a field sharing buffers, how the system reacts to an attempt to
5428enter more data into the field than the buffer will currently hold
5429will depend on the setting of the option in the current field.</p>
5430</li>
5431<li>
5432<p>The library call field_info will work as usual; the variable
5433nrow will contain the value of the original call to new_field. The
5434user should use dynamic_field_info, described above, to query the
5435current size of the buffer.</p>
5436</li>
5437</ol>
5438<p>Some of the above points make sense only after explaining form
5439driver. We will be looking into that in next few sections.</p>
5440</div>
5441</div>
5442<div class="SECT2">
5443<hr>
5444<h3 class="SECT2"><a name="FORMWINDOWS" id="FORMWINDOWS">18.4. Form
5445Windows</a></h3>
5446<p>The form windows concept is pretty much similar to menu windows.
5447Every form is associated with a main window and a sub window. The
5448form main window displays any title or border associated or
5449whatever the user wishes. Then the sub window contains all the
5450fields and displays them according to their position. This gives
5451the flexibility of manipulating fancy form displaying very
5452easily.</p>
5453<p>Since this is pretty much similar to menu windows, I am
5454providing an example with out much explanation. The functions are
5455similar and they work the same way.</p>
5456<div class="EXAMPLE"><a name="FFOWI" id="FFOWI"></a>
5457<p><b>Example 28. Form Windows Example</b></p>
5458<table border="0" bgcolor="#E0E0E0" width="100%">
5459<tr>
5460<td>
5461<pre class="PROGRAMLISTING">
5462<font color="#000000"><span class=
5463"INLINEMEDIAOBJECT">#include &lt;form.h&gt;
5464
5465void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color);
5466
5467int main()
5468{
5469 FIELD *field[3];
5470 FORM *my_form;
5471 WINDOW *my_form_win;
5472 int ch, rows, cols;
5473
5474 /* Initialize curses */
5475 initscr();
5476 start_color();
5477 cbreak();
5478 noecho();
5479 keypad(stdscr, TRUE);
5480
5481 /* Initialize few color pairs */
5482 init_pair(1, COLOR_RED, COLOR_BLACK);
5483
5484 /* Initialize the fields */
5485 field[0] = new_field(1, 10, 6, 1, 0, 0);
5486 field[1] = new_field(1, 10, 8, 1, 0, 0);
5487 field[2] = NULL;
5488
5489 /* Set field options */
5490 set_field_back(field[0], A_UNDERLINE);
5491 field_opts_off(field[0], O_AUTOSKIP); /* Don't go to next field when this */
5492 /* Field is filled up */
5493 set_field_back(field[1], A_UNDERLINE);
5494 field_opts_off(field[1], O_AUTOSKIP);
5495
5496 /* Create the form and post it */
5497 my_form = new_form(field);
5498
5499 /* Calculate the area required for the form */
5500 scale_form(my_form, &amp;rows, &amp;cols);
5501
5502 /* Create the window to be associated with the form */
5503 my_form_win = newwin(rows + 4, cols + 4, 4, 4);
5504 keypad(my_form_win, TRUE);
5505
5506 /* Set main window and sub window */
5507 set_form_win(my_form, my_form_win);
5508 set_form_sub(my_form, derwin(my_form_win, rows, cols, 2, 2));
5509
5510 /* Print a border around the main window and print a title */
5511 box(my_form_win, 0, 0);
5512 print_in_middle(my_form_win, 1, 0, cols + 4, "My Form", COLOR_PAIR(1));
5513
5514 post_form(my_form);
5515 wrefresh(my_form_win);
5516
5517 mvprintw(LINES - 2, 0, "Use UP, DOWN arrow keys to switch between fields");
5518 refresh();
5519
5520 /* Loop through to get user requests */
5521 while((ch = wgetch(my_form_win)) != KEY_F(1))
5522 { switch(ch)
5523 { case KEY_DOWN:
5524 /* Go to next field */
5525 form_driver(my_form, REQ_NEXT_FIELD);
5526 /* Go to the end of the present buffer */
5527 /* Leaves nicely at the last character */
5528 form_driver(my_form, REQ_END_LINE);
5529 break;
5530 case KEY_UP:
5531 /* Go to previous field */
5532 form_driver(my_form, REQ_PREV_FIELD);
5533 form_driver(my_form, REQ_END_LINE);
5534 break;
5535 default:
5536 /* If this is a normal character, it gets */
5537 /* Printed */
5538 form_driver(my_form, ch);
5539 break;
5540 }
5541 }
5542
5543 /* Un post form and free the memory */
5544 unpost_form(my_form);
5545 free_form(my_form);
5546 free_field(field[0]);
5547 free_field(field[1]);
5548
5549 endwin();
5550 return 0;
5551}
5552
5553void print_in_middle(WINDOW *win, int starty, int startx, int width, char *string, chtype color)
5554{ int length, x, y;
5555 float temp;
5556
5557 if(win == NULL)
5558 win = stdscr;
5559 getyx(win, y, x);
5560 if(startx != 0)
5561 x = startx;
5562 if(starty != 0)
5563 y = starty;
5564 if(width == 0)
5565 width = 80;
5566
5567 length = strlen(string);
5568 temp = (width - length)/ 2;
5569 x = startx + (int)temp;
5570 wattron(win, color);
5571 mvwprintw(win, y, x, "%s", string);
5572 wattroff(win, color);
5573 refresh();
5574}</span></font>
5575</pre></td>
5576</tr>
5577</table>
5578</div>
5579</div>
5580<div class="SECT2">
5581<hr>
5582<h3 class="SECT2"><a name="FILEDVALIDATE" id="FILEDVALIDATE">18.5.
5583Field Validation</a></h3>
5584<p>By default, a field will accept any data input by the user. It
5585is possible to attach validation to the field. Then any attempt by
5586the user to leave the field, while it contains data that doesn't
5587match the validation type will fail. Some validation types also
5588have a character-validity check for each time a character is
5589entered in the field.</p>
5590<p>Validation can be attached to a field with the following
5591function.</p>
5592<table border="0" bgcolor="#E0E0E0" width="100%">
5593<tr>
5594<td>
5595<pre class="PROGRAMLISTING">
5596<font color=
5597"#000000">int set_field_type(FIELD *field, /* field to alter */
5598 FIELDTYPE *ftype, /* type to associate */
5599 ...); /* additional arguments*/</font>
5600</pre></td>
5601</tr>
5602</table>
5603Once set, the validation type for a field can be queried with
5604<table border="0" bgcolor="#E0E0E0" width="100%">
5605<tr>
5606<td>
5607<pre class="PROGRAMLISTING">
5608<font color=
5609"#000000">FIELDTYPE *field_type(FIELD *field); /* field to query */</font>
5610</pre></td>
5611</tr>
5612</table>
5613<p>The form driver validates the data in a field only when data is
5614entered by the end-user. Validation does not occur when</p>
5615<ul>
5616<li>
5617<p>the application program changes the field value by calling
5618set_field_buffer.</p>
5619</li>
5620<li>
5621<p>linked field values are changed indirectly -- by changing the
5622field to which they are linked</p>
5623</li>
5624</ul>
5625<p>The following are the pre-defined validation types. You can also
5626specify custom validation, though it's a bit tricky and
5627cumbersome.</p>
5628<h1 class="BRIDGEHEAD"><a name="AEN1069" id=
5629"AEN1069"></a>TYPE_ALPHA</h1>
5630<p>This field type accepts alphabetic data; no blanks, no digits,
5631no special characters (this is checked at character-entry time). It
5632is set up with:</p>
5633<table border="0" bgcolor="#E0E0E0" width="100%">
5634<tr>
5635<td>
5636<pre class="PROGRAMLISTING">
5637<font color=
5638"#000000">int set_field_type(FIELD *field, /* field to alter */
5639 TYPE_ALPHA, /* type to associate */
5640 int width); /* maximum width of field */</font>
5641</pre></td>
5642</tr>
5643</table>
5644<p>The width argument sets a minimum width of data. The user has to
5645enter at-least width number of characters before he can leave the
5646field. Typically you'll want to set this to the field width; if
5647it's greater than the field width, the validation check will always
5648fail. A minimum width of zero makes field completion optional.</p>
5649<h1 class="BRIDGEHEAD"><a name="AEN1073" id=
5650"AEN1073"></a>TYPE_ALNUM</h1>
5651<p>This field type accepts alphabetic data and digits; no blanks,
5652no special characters (this is checked at character-entry time). It
5653is set up with:</p>
5654<table border="0" bgcolor="#E0E0E0" width="100%">
5655<tr>
5656<td>
5657<pre class="PROGRAMLISTING">
5658<font color=
5659"#000000">int set_field_type(FIELD *field, /* field to alter */
5660 TYPE_ALNUM, /* type to associate */
5661 int width); /* maximum width of field */</font>
5662</pre></td>
5663</tr>
5664</table>
5665<p>The width argument sets a minimum width of data. As with
5666TYPE_ALPHA, typically you'll want to set this to the field width;
5667if it's greater than the field width, the validation check will
5668always fail. A minimum width of zero makes field completion
5669optional.</p>
5670<h1 class="BRIDGEHEAD"><a name="AEN1077" id=
5671"AEN1077"></a>TYPE_ENUM</h1>
5672<p>This type allows you to restrict a field's values to be among a
5673specified set of string values (for example, the two-letter postal
5674codes for U.S. states). It is set up with:</p>
5675<table border="0" bgcolor="#E0E0E0" width="100%">
5676<tr>
5677<td>
5678<pre class="PROGRAMLISTING">
5679<font color=
5680"#000000">int set_field_type(FIELD *field, /* field to alter */
5681 TYPE_ENUM, /* type to associate */
5682 char **valuelist; /* list of possible values */
5683 int checkcase; /* case-sensitive? */
5684 int checkunique); /* must specify uniquely? */</font>
5685</pre></td>
5686</tr>
5687</table>
5688<p>The valuelist parameter must point at a NULL-terminated list of
5689valid strings. The checkcase argument, if true, makes comparison
5690with the string case-sensitive.</p>
5691<p>When the user exits a TYPE_ENUM field, the validation procedure
5692tries to complete the data in the buffer to a valid entry. If a
5693complete choice string has been entered, it is of course valid. But
5694it is also possible to enter a prefix of a valid string and have it
5695completed for you.</p>
5696<p>By default, if you enter such a prefix and it matches more than
5697one value in the string list, the prefix will be completed to the
5698first matching value. But the checkunique argument, if true,
5699requires prefix matches to be unique in order to be valid.</p>
5700<p>The REQ_NEXT_CHOICE and REQ_PREV_CHOICE input requests can be
5701particularly useful with these fields.</p>
5702<h1 class="BRIDGEHEAD"><a name="AEN1084" id=
5703"AEN1084"></a>TYPE_INTEGER</h1>
5704<p>This field type accepts an integer. It is set up as follows:</p>
5705<table border="0" bgcolor="#E0E0E0" width="100%">
5706<tr>
5707<td>
5708<pre class="PROGRAMLISTING">
5709<font color=
5710"#000000">int set_field_type(FIELD *field, /* field to alter */
5711 TYPE_INTEGER, /* type to associate */
5712 int padding, /* # places to zero-pad to */
5713 int vmin, int vmax); /* valid range */</font>
5714</pre></td>
5715</tr>
5716</table>
5717<p>Valid characters consist of an optional leading minus and
5718digits. The range check is performed on exit. If the range maximum
5719is less than or equal to the minimum, the range is ignored.</p>
5720<p>If the value passes its range check, it is padded with as many
5721leading zero digits as necessary to meet the padding argument.</p>
5722<p>A TYPE_INTEGER value buffer can conveniently be interpreted with
5723the C library function atoi(3).</p>
5724<h1 class="BRIDGEHEAD"><a name="AEN1090" id=
5725"AEN1090"></a>TYPE_NUMERIC</h1>
5726<p>This field type accepts a decimal number. It is set up as
5727follows:</p>
5728<table border="0" bgcolor="#E0E0E0" width="100%">
5729<tr>
5730<td>
5731<pre class="PROGRAMLISTING">
5732<font color=
5733"#000000">int set_field_type(FIELD *field, /* field to alter */
5734 TYPE_NUMERIC, /* type to associate */
5735 int padding, /* # places of precision */
5736 int vmin, int vmax); /* valid range */</font>
5737</pre></td>
5738</tr>
5739</table>
5740<p>Valid characters consist of an optional leading minus and
5741digits. possibly including a decimal point. The range check is
5742performed on exit. If the range maximum is less than or equal to
5743the minimum, the range is ignored.</p>
5744<p>If the value passes its range check, it is padded with as many
5745trailing zero digits as necessary to meet the padding argument.</p>
5746<p>A TYPE_NUMERIC value buffer can conveniently be interpreted with
5747the C library function atof(3).</p>
5748<h1 class="BRIDGEHEAD"><a name="AEN1096" id=
5749"AEN1096"></a>TYPE_REGEXP</h1>
5750<p>This field type accepts data matching a regular expression. It
5751is set up as follows:</p>
5752<table border="0" bgcolor="#E0E0E0" width="100%">
5753<tr>
5754<td>
5755<pre class="PROGRAMLISTING">
5756<font color=
5757"#000000">int set_field_type(FIELD *field, /* field to alter */
5758 TYPE_REGEXP, /* type to associate */
5759 char *regexp); /* expression to match */</font>
5760</pre></td>
5761</tr>
5762</table>
5763<p>The syntax for regular expressions is that of regcomp(3). The
5764check for regular-expression match is performed on exit.</p>
5765</div>
5766<div class="SECT2">
5767<hr>
5768<h3 class="SECT2"><a name="FORMDRIVER" id="FORMDRIVER">18.6. Form
5769Driver: The work horse of the forms system</a></h3>
5770<p>As in the menu system, form_driver() plays a very important role
5771in forms system. All types of requests to forms system should be
5772funneled through form_driver().</p>
5773<table border="0" bgcolor="#E0E0E0" width="100%">
5774<tr>
5775<td>
5776<pre class="PROGRAMLISTING">
5777<font color=
5778"#000000">int form_driver(FORM *form, /* form on which to operate */
5779 int request) /* form request code */</font>
5780</pre></td>
5781</tr>
5782</table>
5783<p>As you have seen some of the examples above, you have to be in a
5784loop looking for user input and then decide whether it's a field
5785data or a form request. The form requests are then passed to
5786form_driver() to do the work.</p>
5787<p>The requests roughly can be divided into following categories.
5788Different requests and their usage is explained below:</p>
5789<div class="SECT3">
5790<hr>
5791<h4 class="SECT3"><a name="PAGENAVREQ" id="PAGENAVREQ">18.6.1. Page
5792Navigation Requests</a></h4>
5793<p>These requests cause page-level moves through the form,
5794triggering display of a new form screen. A form can be made of
5795multiple pages. If you have a big form with lot of fields and
5796logical sections, then you can divide the form into pages. The
5797function set_new_page() to set a new page at the field
5798specified.</p>
5799<table border="0" bgcolor="#E0E0E0" width="100%">
5800<tr>
5801<td>
5802<pre class="PROGRAMLISTING">
5803<font color=
5804"#000000">int set_new_page(FIELD *field,/* Field at which page break to be set or unset */
5805 bool new_page_flag); /* should be TRUE to put a break */</font>
5806</pre></td>
5807</tr>
5808</table>
5809<p>The following requests allow you to move to different pages</p>
5810<ul>
5811<li>
5812<p><em>REQ_NEXT_PAGE</em> Move to the next form page.</p>
5813</li>
5814<li>
5815<p><em>REQ_PREV_PAGE</em> Move to the previous form page.</p>
5816</li>
5817<li>
5818<p><em>REQ_FIRST_PAGE</em> Move to the first form page.</p>
5819</li>
5820<li>
5821<p><em>REQ_LAST_PAGE</em> Move to the last form page.</p>
5822</li>
5823</ul>
5824<p>These requests treat the list as cyclic; that is, REQ_NEXT_PAGE
5825from the last page goes to the first, and REQ_PREV_PAGE from the
5826first page goes to the last.</p>
5827</div>
5828<div class="SECT3">
5829<hr>
5830<h4 class="SECT3"><a name="INTERFIELDNAVREQ" id=
5831"INTERFIELDNAVREQ">18.6.2. Inter-Field Navigation Requests</a></h4>
5832<p>These requests handle navigation between fields on the same
5833page.</p>
5834<ul>
5835<li>
5836<p><em>REQ_NEXT_FIELD</em> Move to next field.</p>
5837</li>
5838<li>
5839<p><em>REQ_PREV_FIELD</em> Move to previous field.</p>
5840</li>
5841<li>
5842<p><em>REQ_FIRST_FIELD</em> Move to the first field.</p>
5843</li>
5844<li>
5845<p><em>REQ_LAST_FIELD</em> Move to the last field.</p>
5846</li>
5847<li>
5848<p><em>REQ_SNEXT_FIELD</em> Move to sorted next field.</p>
5849</li>
5850<li>
5851<p><em>REQ_SPREV_FIELD</em> Move to sorted previous field.</p>
5852</li>
5853<li>
5854<p><em>REQ_SFIRST_FIELD</em> Move to the sorted first field.</p>
5855</li>
5856<li>
5857<p><em>REQ_SLAST_FIELD</em> Move to the sorted last field.</p>
5858</li>
5859<li>
5860<p><em>REQ_LEFT_FIELD</em> Move left to field.</p>
5861</li>
5862<li>
5863<p><em>REQ_RIGHT_FIELD</em> Move right to field.</p>
5864</li>
5865<li>
5866<p><em>REQ_UP_FIELD</em> Move up to field.</p>
5867</li>
5868<li>
5869<p><em>REQ_DOWN_FIELD</em> Move down to field.</p>
5870</li>
5871</ul>
5872<p>These requests treat the list of fields on a page as cyclic;
5873that is, REQ_NEXT_FIELD from the last field goes to the first, and
5874REQ_PREV_FIELD from the first field goes to the last. The order of
5875the fields for these (and the REQ_FIRST_FIELD and REQ_LAST_FIELD
5876requests) is simply the order of the field pointers in the form
5877array (as set up by new_form() or set_form_fields()</p>
5878<p>It is also possible to traverse the fields as if they had been
5879sorted in screen-position order, so the sequence goes left-to-right
5880and top-to-bottom. To do this, use the second group of four
5881sorted-movement requests.</p>
5882<p>Finally, it is possible to move between fields using visual
5883directions up, down, right, and left. To accomplish this, use the
5884third group of four requests. Note, however, that the position of a
5885form for purposes of these requests is its upper-left corner.</p>
5886<p>For example, suppose you have a multi-line field B, and two
5887single-line fields A and C on the same line with B, with A to the
5888left of B and C to the right of B. A REQ_MOVE_RIGHT from A will go
5889to B only if A, B, and C all share the same first line; otherwise
5890it will skip over B to C.</p>
5891</div>
5892<div class="SECT3">
5893<hr>
5894<h4 class="SECT3"><a name="INTRAFIELDNAVREQ" id=
5895"INTRAFIELDNAVREQ">18.6.3. Intra-Field Navigation Requests</a></h4>
5896<p>These requests drive movement of the edit cursor within the
5897currently selected field.</p>
5898<ul>
5899<li>
5900<p><em>REQ_NEXT_CHAR</em> Move to next character.</p>
5901</li>
5902<li>
5903<p><em>REQ_PREV_CHAR</em> Move to previous character.</p>
5904</li>
5905<li>
5906<p><em>REQ_NEXT_LINE</em> Move to next line.</p>
5907</li>
5908<li>
5909<p><em>REQ_PREV_LINE</em> Move to previous line.</p>
5910</li>
5911<li>
5912<p><em>REQ_NEXT_WORD</em> Move to next word.</p>
5913</li>
5914<li>
5915<p><em>REQ_PREV_WORD</em> Move to previous word.</p>
5916</li>
5917<li>
5918<p><em>REQ_BEG_FIELD</em> Move to beginning of field.</p>
5919</li>
5920<li>
5921<p><em>REQ_END_FIELD</em> Move to end of field.</p>
5922</li>
5923<li>
5924<p><em>REQ_BEG_LINE</em> Move to beginning of line.</p>
5925</li>
5926<li>
5927<p><em>REQ_END_LINE</em> Move to end of line.</p>
5928</li>
5929<li>
5930<p><em>REQ_LEFT_CHAR</em> Move left in field.</p>
5931</li>
5932<li>
5933<p><em>REQ_RIGHT_CHAR</em> Move right in field.</p>
5934</li>
5935<li>
5936<p><em>REQ_UP_CHAR</em> Move up in field.</p>
5937</li>
5938<li>
5939<p><em>REQ_DOWN_CHAR</em> Move down in field.</p>
5940</li>
5941</ul>
5942<p>Each word is separated from the previous and next characters by
5943whitespace. The commands to move to beginning and end of line or
5944field look for the first or last non-pad character in their
5945ranges.</p>
5946</div>
5947<div class="SECT3">
5948<hr>
5949<h4 class="SECT3"><a name="SCROLLREQ" id="SCROLLREQ">18.6.4.
5950Scrolling Requests</a></h4>
5951<p>Fields that are dynamic and have grown and fields explicitly
5952created with offscreen rows are scrollable. One-line fields scroll
5953horizontally; multi-line fields scroll vertically. Most scrolling
5954is triggered by editing and intra-field movement (the library
5955scrolls the field to keep the cursor visible). It is possible to
5956explicitly request scrolling with the following requests:</p>
5957<ul>
5958<li>
5959<p><em>REQ_SCR_FLINE</em> Scroll vertically forward a line.</p>
5960</li>
5961<li>
5962<p><em>REQ_SCR_BLINE</em> Scroll vertically backward a line.</p>
5963</li>
5964<li>
5965<p><em>REQ_SCR_FPAGE</em> Scroll vertically forward a page.</p>
5966</li>
5967<li>
5968<p><em>REQ_SCR_BPAGE</em> Scroll vertically backward a page.</p>
5969</li>
5970<li>
5971<p><em>REQ_SCR_FHPAGE</em> Scroll vertically forward half a
5972page.</p>
5973</li>
5974<li>
5975<p><em>REQ_SCR_BHPAGE</em> Scroll vertically backward half a
5976page.</p>
5977</li>
5978<li>
5979<p><em>REQ_SCR_FCHAR</em> Scroll horizontally forward a
5980character.</p>
5981</li>
5982<li>
5983<p><em>REQ_SCR_BCHAR</em> Scroll horizontally backward a
5984character.</p>
5985</li>
5986<li>
5987<p><em>REQ_SCR_HFLINE</em> Scroll horizontally one field width
5988forward.</p>
5989</li>
5990<li>
5991<p><em>REQ_SCR_HBLINE</em> Scroll horizontally one field width
5992backward.</p>
5993</li>
5994<li>
5995<p><em>REQ_SCR_HFHALF</em> Scroll horizontally one half field width
5996forward.</p>
5997</li>
5998<li>
5999<p><em>REQ_SCR_HBHALF</em> Scroll horizontally one half field width
6000backward.</p>
6001</li>
6002</ul>
6003<p>For scrolling purposes, a page of a field is the height of its
6004visible part.</p>
6005</div>
6006<div class="SECT3">
6007<hr>
6008<h4 class="SECT3"><a name="EDITREQ" id="EDITREQ">18.6.5. Editing
6009Requests</a></h4>
6010<p>When you pass the forms driver an ASCII character, it is treated
6011as a request to add the character to the field's data buffer.
6012Whether this is an insertion or a replacement depends on the
6013field's edit mode (insertion is the default.</p>
6014<p>The following requests support editing the field and changing
6015the edit mode:</p>
6016<ul>
6017<li>
6018<p><em>REQ_INS_MODE</em> Set insertion mode.</p>
6019</li>
6020<li>
6021<p><em>REQ_OVL_MODE</em> Set overlay mode.</p>
6022</li>
6023<li>
6024<p><em>REQ_NEW_LINE</em> New line request (see below for
6025explanation).</p>
6026</li>
6027<li>
6028<p><em>REQ_INS_CHAR</em> Insert space at character location.</p>
6029</li>
6030<li>
6031<p><em>REQ_INS_LINE</em> Insert blank line at character
6032location.</p>
6033</li>
6034<li>
6035<p><em>REQ_DEL_CHAR</em> Delete character at cursor.</p>
6036</li>
6037<li>
6038<p><em>REQ_DEL_PREV</em> Delete previous word at cursor.</p>
6039</li>
6040<li>
6041<p><em>REQ_DEL_LINE</em> Delete line at cursor.</p>
6042</li>
6043<li>
6044<p><em>REQ_DEL_WORD</em> Delete word at cursor.</p>
6045</li>
6046<li>
6047<p><em>REQ_CLR_EOL</em> Clear to end of line.</p>
6048</li>
6049<li>
6050<p><em>REQ_CLR_EOF</em> Clear to end of field.</p>
6051</li>
6052<li>
6053<p><em>REQ_CLR_FIELD</em> Clear entire field.</p>
6054</li>
6055</ul>
6056<p>The behavior of the REQ_NEW_LINE and REQ_DEL_PREV requests is
6057complicated and partly controlled by a pair of forms options. The
6058special cases are triggered when the cursor is at the beginning of
6059a field, or on the last line of the field.</p>
6060<p>First, we consider REQ_NEW_LINE:</p>
6061<p>The normal behavior of REQ_NEW_LINE in insert mode is to break
6062the current line at the position of the edit cursor, inserting the
6063portion of the current line after the cursor as a new line
6064following the current and moving the cursor to the beginning of
6065that new line (you may think of this as inserting a newline in the
6066field buffer).</p>
6067<p>The normal behavior of REQ_NEW_LINE in overlay mode is to clear
6068the current line from the position of the edit cursor to end of
6069line. The cursor is then moved to the beginning of the next
6070line.</p>
6071<p>However, REQ_NEW_LINE at the beginning of a field, or on the
6072last line of a field, instead does a REQ_NEXT_FIELD. O_NL_OVERLOAD
6073option is off, this special action is disabled.</p>
6074<p>Now, let us consider REQ_DEL_PREV:</p>
6075<p>The normal behavior of REQ_DEL_PREV is to delete the previous
6076character. If insert mode is on, and the cursor is at the start of
6077a line, and the text on that line will fit on the previous one, it
6078instead appends the contents of the current line to the previous
6079one and deletes the current line (you may think of this as deleting
6080a newline from the field buffer).</p>
6081<p>However, REQ_DEL_PREV at the beginning of a field is instead
6082treated as a REQ_PREV_FIELD.</p>
6083<p>If the O_BS_OVERLOAD option is off, this special action is
6084disabled and the forms driver just returns E_REQUEST_DENIED.</p>
6085</div>
6086<div class="SECT3">
6087<hr>
6088<h4 class="SECT3"><a name="ORDERREQ" id="ORDERREQ">18.6.6. Order
6089Requests</a></h4>
6090<p>If the type of your field is ordered, and has associated
6091functions for getting the next and previous values of the type from
6092a given value, there are requests that can fetch that value into
6093the field buffer:</p>
6094<ul>
6095<li>
6096<p><em>REQ_NEXT_CHOICE</em> Place the successor value of the
6097current value in the buffer.</p>
6098</li>
6099<li>
6100<p><em>REQ_PREV_CHOICE</em> Place the predecessor value of the
6101current value in the buffer.</p>
6102</li>
6103</ul>
6104<p>Of the built-in field types, only TYPE_ENUM has built-in
6105successor and predecessor functions. When you define a field type
6106of your own (see Custom Validation Types), you can associate our
6107own ordering functions.</p>
6108</div>
6109<div class="SECT3">
6110<hr>
6111<h4 class="SECT3"><a name="APPLICCOMMANDS" id=
6112"APPLICCOMMANDS">18.6.7. Application Commands</a></h4>
6113<p>Form requests are represented as integers above the curses value
6114greater than KEY_MAX and less than or equal to the constant
6115MAX_COMMAND. A value within this range gets ignored by
6116form_driver(). So this can be used for any purpose by the
6117application. It can be treated as an application specific action
6118and take corresponding action.</p>
6119</div>
6120</div>
6121</div>
6122<div class="SECT1">
6123<hr>
6124<h2 class="SECT1"><a name="TOOLS" id="TOOLS">19. Tools and Widget
6125Libraries</a></h2>
6126<p>Now that you have seen the capabilities of ncurses and its
6127sister libraries, you are rolling your sleeves up and gearing for a
6128project that heavily manipulates screen. But wait.. It can be
6129pretty difficult to write and maintain complex GUI widgets in plain
6130ncurses or even with the additional libraries. There are some
6131ready-to-use tools and widget libraries that can be used instead of
6132writing your own widgets. You can use some of them, get ideas from
6133the code, or even extend them.</p>
6134<div class="SECT2">
6135<hr>
6136<h3 class="SECT2"><a name="CDK" id="CDK">19.1. CDK (Curses
6137Development Kit)</a></h3>
6138<p>In the author's words</p>
6139<p><em>CDK stands for 'Curses Development Kit' and it currently
6140contains 21 ready to use widgets which facilitate the speedy
6141development of full screen curses programs.</em></p>
6142<p>The kit provides some useful widgets, which can be used in your
6143programs directly. It's pretty well written and the documentation
6144is very good. The examples in the examples directory can be a good
6145place to start for beginners. The CDK can be downloaded from
6146<a href="http://invisible-island.net/cdk/" target=
6147"_top">http://invisible-island.net/cdk/</a> . Follow the
6148instructions in README file to install it.</p>
6149<div class="SECT3">
6150<hr>
6151<h4 class="SECT3"><a name="WIDGETLIST" id="WIDGETLIST">19.1.1.
6152Widget List</a></h4>
6153<p>The following is the list of widgets provided with cdk and their
6154description.</p>
6155<table border="0" bgcolor="#E0E0E0" width="100%">
6156<tr>
6157<td>
6158<pre class="PROGRAMLISTING">
6159<font color="#000000">Widget Type Quick Description
6160===========================================================================
6161Alphalist Allows a user to select from a list of words, with
6162 the ability to narrow the search list by typing in a
6163 few characters of the desired word.
6164Buttonbox This creates a multiple button widget.
6165Calendar Creates a little simple calendar widget.
6166Dialog Prompts the user with a message, and the user
6167 can pick an answer from the buttons provided.
6168Entry Allows the user to enter various types of information.
6169File Selector A file selector built from Cdk base widgets. This
6170 example shows how to create more complicated widgets
6171 using the Cdk widget library.
6172Graph Draws a graph.
6173Histogram Draws a histogram.
6174Item List Creates a pop up field which allows the user to select
6175 one of several choices in a small field. Very useful
6176 for things like days of the week or month names.
6177Label Displays messages in a pop up box, or the label can be
6178 considered part of the screen.
6179Marquee Displays a message in a scrolling marquee.
6180Matrix Creates a complex matrix with lots of options.
6181Menu Creates a pull-down menu interface.
6182Multiple Line Entry A multiple line entry field. Very useful
6183 for long fields. (like a description
6184 field)
6185Radio List Creates a radio button list.
6186Scale Creates a numeric scale. Used for allowing a user to
6187 pick a numeric value and restrict them to a range of
6188 values.
6189Scrolling List Creates a scrolling list/menu list.
6190Scrolling Window Creates a scrolling log file viewer. Can add
6191 information into the window while its running.
6192 A good widget for displaying the progress of
6193 something. (akin to a console window)
6194Selection List Creates a multiple option selection list.
6195Slider Akin to the scale widget, this widget provides a
6196 visual slide bar to represent the numeric value.
6197Template Creates a entry field with character sensitive
6198 positions. Used for pre-formatted fields like
6199 dates and phone numbers.
6200Viewer This is a file/information viewer. Very useful
6201 when you need to display loads of information.
6202===========================================================================</font>
6203</pre></td>
6204</tr>
6205</table>
6206<p>A few of the widgets are modified by Thomas Dickey in recent
6207versions.</p>
6208</div>
6209<div class="SECT3">
6210<hr>
6211<h4 class="SECT3"><a name="CDKATTRACT" id="CDKATTRACT">19.1.2. Some
6212Attractive Features</a></h4>
6213<p>Apart from making our life easier with readily usable widgets,
6214cdk solves one frustrating problem with printing multi colored
6215strings, justified strings elegantly. Special formatting tags can
6216be embedded in the strings which are passed to CDK functions. For
6217Example</p>
6218<p>If the string</p>
6219<table border="0" bgcolor="#E0E0E0" width="100%">
6220<tr>
6221<td>
6222<pre class="PROGRAMLISTING">
6223<font color=
6224"#000000">"&lt;/B/1&gt;This line should have a yellow foreground and a blue
6225background.&lt;!1&gt;"</font>
6226</pre></td>
6227</tr>
6228</table>
6229<p>given as a parameter to newCDKLabel(), it prints the line with
6230yellow foreground and blue background. There are other tags
6231available for justifying string, embedding special drawing
6232characters etc.. Please refer to the man page cdk_display(3X) for
6233details. The man page explains the usage with nice examples.</p>
6234</div>
6235<div class="SECT3">
6236<hr>
6237<h4 class="SECT3"><a name="CDKCONCLUSION" id=
6238"CDKCONCLUSION">19.1.3. Conclusion</a></h4>
6239<p>All in all, CDK is a well-written package of widgets, which if
6240used properly can form a strong frame work for developing complex
6241GUI.</p>
6242</div>
6243</div>
6244<div class="SECT2">
6245<hr>
6246<h3 class="SECT2"><a name="DIALOG" id="DIALOG">19.2. The
6247dialog</a></h3>
6248<p>Long long ago, in September 1994, when few people knew linux,
6249Jeff Tranter wrote an <a href=
6250"http://www2.linuxjournal.com/lj-issues/issue5/2807.html" target=
6251"_top">article</a> on dialog in Linux Journal. He starts the
6252article with these words..</p>
6253<p><em>Linux is based on the Unix operating system, but also
6254features a number of unique and useful kernel features and
6255application programs that often go beyond what is available under
6256Unix. One little-known gem is "dialog", a utility for creating
6257professional-looking dialog boxes from within shell scripts. This
6258article presents a tutorial introduction to the dialog utility, and
6259shows examples of how and where it can be used</em></p>
6260<p>As he explains, dialog is a real gem in making
6261professional-looking dialog boxes with ease. It creates a variety
6262of dialog boxes, menus, check lists etc.. It is usually installed
6263by default. If not, you can download it from <a href=
6264"http://invisible-island.net/dialog/" target="_top">Thomas
6265Dickey</a>'s site.</p>
6266<p>The above-mentioned article gives a very good overview of its
6267uses and capabilites. The man page has more details. It can be used
6268in variety of situations. One good example is building of linux
6269kernel in text mode. Linux kernel uses a modified version of dialog
6270tailored for its needs.</p>
6271<p>dialog was initially designed to be used with shell scripts. If
6272you want to use its functionality in a c program, then you can use
6273libdialog. The documentation regarding this is sparse. Definitive
6274reference is the dialog.h header file which comes with the library.
6275You may need to hack here and there to get the required output. The
6276source is easily customizable. I have used it on a number of
6277occasions by modifying the code.</p>
6278</div>
6279<div class="SECT2">
6280<hr>
6281<h3 class="SECT2"><a name="PERLCURSES" id="PERLCURSES">19.3. Perl
6282Curses Modules CURSES::FORM and CURSES::WIDGETS</a></h3>
6283<p>The perl module Curses, Curses::Form and Curses::Widgets give
6284access to curses from perl. If you have curses and basic perl is
6285installed, you can get these modules from <a href=
6286"http://www.cpan.org/modules/01modules.index.html" target=
6287"_top">CPAN All Modules page</a>. Get the three zipped modules in
6288the Curses category. Once installed you can use these modules from
6289perl scripts like any other module. For more information on perl
6290modules see perlmod man page. The above modules come with good
6291documentation and they have some demo scripts to test the
6292functionality. Though the widgets provided are very rudimentary,
6293these modules provide good access to curses library from perl.</p>
6294<p>Some of my code examples are converted to perl by Anuradha
6295Ratnaweera and they are available in the <var class=
6296"LITERAL">perl</var> directory.</p>
6297<p>For more information see man pages Curses(3) , Curses::Form(3)
6298and Curses::Widgets(3). These pages are installed only when the
6299above modules are acquired and installed.</p>
6300</div>
6301</div>
6302<div class="SECT1">
6303<hr>
6304<h2 class="SECT1"><a name="JUSTFORFUN" id="JUSTFORFUN">20. Just For
6305Fun !!!</a></h2>
6306<p>This section contains few programs written by me just for fun.
6307They don't signify a better programming practice or the best way of
6308using ncurses. They are provided here so as to allow beginners to
6309get ideas and add more programs to this section. If you have
6310written a couple of nice, simple programs in curses and want them
6311to included here, contact <a href="mailto:ppadala@gmail.com"
6312target="_top">me</a>.</p>
6313<div class="SECT2">
6314<hr>
6315<h3 class="SECT2"><a name="GAMEOFLIFE" id="GAMEOFLIFE">20.1. The
6316Game of Life</a></h3>
6317<p>Game of life is a wonder of math. In <a href=
6318"http://www.math.com/students/wonders/life/life.html" target=
6319"_top">Paul Callahan</a>'s words</p>
6320<table border="0" bgcolor="#E0E0E0" width="100%">
6321<tr>
6322<td>
6323<pre class="PROGRAMLISTING">
6324<font color=
6325"#000000"><em>The Game of Life (or simply Life) is not a game in the conventional sense. There
6326are no players, and no winning or losing. Once the "pieces" are placed in the
6327starting position, the rules determine everything that happens later.
6328Nevertheless, Life is full of surprises! In most cases, it is impossible to look
6329at a starting position (or pattern) and see what will happen in the future. The
6330only way to find out is to follow the rules of the game.</em></font>
6331</pre></td>
6332</tr>
6333</table>
6334<p>This program starts with a simple inverted U pattern and shows
6335how wonderful life works. There is a lot of room for improvement in
6336the program. You can let the user enter pattern of his choice or
6337even take input from a file. You can also change rules and play
6338with a lot of variations. Search on <a href="http://www.google.com"
6339target="_top">google</a> for interesting information on game of
6340life.</p>
6341<p><em>File Path: JustForFun/life.c</em></p>
6342</div>
6343<div class="SECT2">
6344<hr>
6345<h3 class="SECT2"><a name="MAGIC" id="MAGIC">20.2. Magic
6346Square</a></h3>
6347<p>Magic Square, another wonder of math, is very simple to
6348understand but very difficult to make. In a magic square sum of the
6349numbers in each row, each column is equal. Even diagnol sum can be
6350equal. There are many variations which have special properties.</p>
6351<p>This program creates a simple magic square of odd order.</p>
6352<p><em>File Path: JustForFun/magic.c</em></p>
6353</div>
6354<div class="SECT2">
6355<hr>
6356<h3 class="SECT2"><a name="HANOI" id="HANOI">20.3. Towers of
6357Hanoi</a></h3>
6358<p>The famous towers of hanoi solver. The aim of the game is to
6359move the disks on the first peg to last peg, using middle peg as a
6360temporary stay. The catch is not to place a larger disk over a
6361small disk at any time.</p>
6362<p><em>File Path: JustForFun/hanoi.c</em></p>
6363</div>
6364<div class="SECT2">
6365<hr>
6366<h3 class="SECT2"><a name="QUEENS" id="QUEENS">20.4. Queens
6367Puzzle</a></h3>
6368<p>The objective of the famous N-Queen puzzle is to put N queens on
6369a N X N chess board without attacking each other.</p>
6370<p>This program solves it with a simple backtracking technique.</p>
6371<p><em>File Path: JustForFun/queens.c</em></p>
6372</div>
6373<div class="SECT2">
6374<hr>
6375<h3 class="SECT2"><a name="SHUFFLE" id="SHUFFLE">20.5.
6376Shuffle</a></h3>
6377<p>A fun game, if you have time to kill.</p>
6378<p><em>File Path: JustForFun/shuffle.c</em></p>
6379</div>
6380<div class="SECT2">
6381<hr>
6382<h3 class="SECT2"><a name="TT" id="TT">20.6. Typing Tutor</a></h3>
6383<p>A simple typing tutor, I created more out of need than for ease
6384of use. If you know how to put your fingers correctly on the
6385keyboard, but lack practice, this can be helpful.</p>
6386<p><em>File Path: JustForFun/tt.c</em></p>
6387</div>
6388</div>
6389<div class="SECT1">
6390<hr>
6391<h2 class="SECT1"><a name="REF" id="REF">21. References</a></h2>
6392<ul>
6393<li>
6394<p>NCURSES man pages</p>
6395</li>
6396<li>
6397<p>NCURSES FAQ at <a href=
6398"http://invisible-island.net/ncurses/ncurses.faq.html" target=
6399"_top">http://invisible-island.net/ncurses/ncurses.faq.html</a></p>
6400</li>
6401<li>
6402<p>Writing programs with NCURSES by Eric Raymond and Zeyd M.
6403Ben-Halim at <a href=
6404"http://invisible-island.net/ncurses/ncurses-intro.html" target=
6405"_top">http://invisible-island.net/ncurses/ncurses-intro.html</a> -
6406somewhat obsolete. I was inspired by this document and the
6407structure of this HOWTO follows from the original document</p>
6408</li>
6409</ul>
6410</div>
6411</div>
6412</body>
6413</html>