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Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]29 * @Id: curs_initscr.3x,v 1.24 2015/07/21 23:01:38 tom Exp @
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Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]36<TITLE>curs_initscr 3x</TITLE>
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Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]41<H1 class="no-header">curs_initscr 3x</H1>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]42<PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]43<STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG> <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>
44
45
46
47
48</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]49<H2><a name="h2-NAME">NAME</a></H2><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]50 <STRONG>initscr</STRONG>, <STRONG>newterm</STRONG>, <STRONG>endwin</STRONG>, <STRONG>isendwin</STRONG>, <STRONG>set_term</STRONG>, <STRONG>delscreen</STRONG> -
51 <STRONG>curses</STRONG> screen initialization and manipulation routines
52
53
54</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]55<H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]56 <STRONG>#include</STRONG> <STRONG>&lt;curses.h&gt;</STRONG>
57
58 <STRONG>WINDOW</STRONG> <STRONG>*initscr(void);</STRONG>
59 <STRONG>int</STRONG> <STRONG>endwin(void);</STRONG>
60 <STRONG>bool</STRONG> <STRONG>isendwin(void);</STRONG>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]61 <STRONG>SCREEN</STRONG> <STRONG>*newterm(char</STRONG> <STRONG>*</STRONG><EM>type</EM><STRONG>,</STRONG> <STRONG>FILE</STRONG> <STRONG>*</STRONG><EM>outfd</EM><STRONG>,</STRONG> <STRONG>FILE</STRONG> <STRONG>*</STRONG><EM>infd</EM><STRONG>);</STRONG>
62 <STRONG>SCREEN</STRONG> <STRONG>*set_term(SCREEN</STRONG> <STRONG>*</STRONG><EM>new</EM><STRONG>);</STRONG>
63 <STRONG>void</STRONG> <STRONG>delscreen(SCREEN*</STRONG> <EM>sp</EM><STRONG>);</STRONG>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]64
65
66</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]67<H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
68
69</PRE>
70<H3><a name="h3-initscr">initscr</a></H3><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]71 <STRONG>initscr</STRONG> is normally the first <STRONG>curses</STRONG> routine to call when
72 initializing a program. A few special routines sometimes
73 need to be called before it; these are <STRONG>slk_init</STRONG>, <STRONG>filter</STRONG>,
74 <STRONG>ripoffline</STRONG>, <STRONG>use_env</STRONG>. For multiple-terminal applications,
75 <STRONG>newterm</STRONG> may be called before <STRONG>initscr</STRONG>.
76
77 The initscr code determines the terminal type and initial-
78 izes all <STRONG>curses</STRONG> data structures. <STRONG>initscr</STRONG> also causes the
79 first call to <STRONG>refresh</STRONG> to clear the screen. If errors oc-
80 cur, <STRONG>initscr</STRONG> writes an appropriate error message to stan-
81 dard error and exits; otherwise, a pointer is returned to
82 <STRONG>stdscr</STRONG>.
83
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]84
85</PRE>
86<H3><a name="h3-newterm">newterm</a></H3><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]87 A program that outputs to more than one terminal should
88 use the <STRONG>newterm</STRONG> routine for each terminal instead of
89 <STRONG>initscr</STRONG>. A program that needs to inspect capabilities, so
90 it can continue to run in a line-oriented mode if the ter-
91 minal cannot support a screen-oriented program, would also
92 use <STRONG>newterm</STRONG>. The routine <STRONG>newterm</STRONG> should be called once
93 for each terminal. It returns a variable of type <STRONG>SCREEN</STRONG> <STRONG>*</STRONG>
94 which should be saved as a reference to that terminal.
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]95 <STRONG>newterm</STRONG>'s arguments are
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]96
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]97 <STRONG>o</STRONG> the <EM>type</EM> of the terminal to be used in place of <STRONG>$TERM</STRONG>,
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]98
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]99 <STRONG>o</STRONG> a file pointer for output to the terminal, and
100
101 <STRONG>o</STRONG> another file pointer for input from the terminal
102
103 If the <EM>type</EM> parameter is <STRONG>NULL</STRONG>, <STRONG>$TERM</STRONG> will be used.
104
105
106</PRE>
107<H3><a name="h3-endwin">endwin</a></H3><PRE>
108 The program must also call <STRONG>endwin</STRONG> for each terminal being
109 used before exiting from <STRONG>curses</STRONG>. If <STRONG>newterm</STRONG> is called
110 more than once for the same terminal, the first terminal
111 referred to must be the last one for which <STRONG>endwin</STRONG> is
112 called.
113
114 A program should always call <STRONG>endwin</STRONG> before exiting or es-
115 caping from <STRONG>curses</STRONG> mode temporarily. This routine
116
117 <STRONG>o</STRONG> restores tty modes,
118
119 <STRONG>o</STRONG> moves the cursor to the lower left-hand corner of the
120 screen and
121
122 <STRONG>o</STRONG> resets the terminal into the proper non-visual mode.
123
124 Calling <STRONG>refresh</STRONG> or <STRONG>doupdate</STRONG> after a temporary escape caus-
125 es the program to resume visual mode.
126
127
128</PRE>
129<H3><a name="h3-isendwin">isendwin</a></H3><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]130 The <STRONG>isendwin</STRONG> routine returns <STRONG>TRUE</STRONG> if <STRONG>endwin</STRONG> has been
131 called without any subsequent calls to <STRONG>wrefresh</STRONG>, and <STRONG>FALSE</STRONG>
132 otherwise.
133
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]134
135</PRE>
136<H3><a name="h3-set_term">set_term</a></H3><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]137 The <STRONG>set_term</STRONG> routine is used to switch between different
138 terminals. The screen reference <STRONG>new</STRONG> becomes the new cur-
139 rent terminal. The previous terminal is returned by the
140 routine. This is the only routine which manipulates
141 <STRONG>SCREEN</STRONG> pointers; all other routines affect only the cur-
142 rent terminal.
143
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]144
145</PRE>
146<H3><a name="h3-delscreen">delscreen</a></H3><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]147 The <STRONG>delscreen</STRONG> routine frees storage associated with the
148 <STRONG>SCREEN</STRONG> data structure. The <STRONG>endwin</STRONG> routine does not do
149 this, so <STRONG>delscreen</STRONG> should be called after <STRONG>endwin</STRONG> if a par-
150 ticular <STRONG>SCREEN</STRONG> is no longer needed.
151
152
153</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]154<H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]155 <STRONG>endwin</STRONG> returns the integer <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> upon
156 successful completion.
157
158 Routines that return pointers always return <STRONG>NULL</STRONG> on error.
159
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]160 X/Open defines no error conditions. In this implementa-
161 tion
162
163 <STRONG>o</STRONG> <STRONG>endwin</STRONG> returns an error if the terminal was not ini-
164 tialized.
165
166 <STRONG>o</STRONG> <STRONG>newterm</STRONG> returns an error if it cannot allocate the da-
167 ta structures for the screen, or for the top-level
168 windows within the screen, i.e., <STRONG>curscr</STRONG>, <STRONG>newscr</STRONG>, or
169 <STRONG>stdscr</STRONG>.
170
171 <STRONG>o</STRONG> <STRONG>set_term</STRONG> returns no error.
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]172
173
174</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]175<H2><a name="h2-NOTES">NOTES</a></H2><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]176 Note that <STRONG>initscr</STRONG> and <STRONG>newterm</STRONG> may be macros.
177
178
179</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]180<H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
181 These functions were described in the XSI Curses standard,
182 Issue 4. As of 2015, the current document is X/Open Curs-
183 es, Issue 7.
184
185
186</PRE>
187<H3><a name="h3-Differences">Differences</a></H3><PRE>
188 X/Open specifies that portable applications must not call
189 <STRONG>initscr</STRONG> more than once:
190
191 <STRONG>o</STRONG> The portable way to use <STRONG>initscr</STRONG> is once only, using
192 <STRONG>refresh</STRONG> (see <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>) to restore the screen
193 after <STRONG>endwin</STRONG>.
194
195 <STRONG>o</STRONG> This implementation allows using <STRONG>initscr</STRONG> after <STRONG>endwin</STRONG>.
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]196
197 Old versions of curses, e.g., BSD 4.4, may have returned a
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]198 null pointer from <STRONG>initscr</STRONG> when an error is detected,
199 rather than exiting. It is safe but redundant to check
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]200 the return value of <STRONG>initscr</STRONG> in XSI Curses.
201
202
203</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]204<H3><a name="h3-Unset-TERM-Variable">Unset TERM Variable</a></H3><PRE>
205 If the TERM variable is missing or empty, <STRONG>initscr</STRONG> uses the
206 value "unknown", which normally corresponds to a terminal
207 entry with the <EM>generic</EM> (<EM>gn</EM>) capability. Generic entries
208 are detected by <STRONG>setupterm</STRONG> (see <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>) and can-
209 not be used for full-screen operation. Other implementa-
210 tions may handle a missing/empty TERM variable different-
211 ly.
212
213
214</PRE>
215<H3><a name="h3-Signal-Handlers">Signal Handlers</a></H3><PRE>
216 Quoting from X/Open Curses, section 3.1.1:
217
218 <EM>Curses</EM> <EM>implementations</EM> <EM>may</EM> <EM>provide</EM> <EM>for</EM> <EM>special</EM> <EM>han-</EM>
219 <EM>dling</EM> <EM>of</EM> <EM>the</EM> <EM>SIGINT,</EM> <EM>SIGQUIT</EM> <EM>and</EM> <EM>SIGTSTP</EM> <EM>signals</EM> <EM>if</EM>
220 <EM>their</EM> <EM>disposition</EM> <EM>is</EM> <EM>SIG</EM><STRONG>_</STRONG><EM>DFL</EM> <EM>at</EM> <EM>the</EM> <EM>time</EM> <STRONG>initscr()</STRONG> <EM>is</EM>
221 <EM>called</EM> <STRONG>...</STRONG>
222
223 <EM>Any</EM> <EM>special</EM> <EM>handling</EM> <EM>for</EM> <EM>these</EM> <EM>signals</EM> <EM>may</EM> <EM>remain</EM> <EM>in</EM>
224 <EM>effect</EM> <EM>for</EM> <EM>the</EM> <EM>life</EM> <EM>of</EM> <EM>the</EM> <EM>process</EM> <EM>or</EM> <EM>until</EM> <EM>the</EM>
225 <EM>process</EM> <EM>changes</EM> <EM>the</EM> <EM>disposition</EM> <EM>of</EM> <EM>the</EM> <EM>signal.</EM>
226
227 <EM>None</EM> <EM>of</EM> <EM>the</EM> <EM>Curses</EM> <EM>functions</EM> <EM>are</EM> <EM>required</EM> <EM>to</EM> <EM>be</EM> <EM>safe</EM>
228 <EM>with</EM> <EM>respect</EM> <EM>to</EM> <EM>signals</EM> ...
229
230 This implementation establishes signal handlers during
231 initialization, e.g., <STRONG>initscr</STRONG> or <STRONG>newterm</STRONG>. Applications
232 which must handle these signals should set up the corre-
233 sponding handlers <EM>after</EM> initializing the library:
234
235 <STRONG>SIGINT</STRONG>
236 The handler <EM>attempts</EM> to cleanup the screen on exit.
237 Although it <EM>usually</EM> works as expected, there are lim-
238 itations:
239
240 <STRONG>o</STRONG> Walking the <STRONG>SCREEN</STRONG> list is unsafe, since all list
241 management is done without any signal blocking.
242
243 <STRONG>o</STRONG> On systems which have <STRONG>REENTRANT</STRONG> turned on,
244 <STRONG>set_term</STRONG> uses functions which could deadlock or
245 misbehave in other ways.
246
247 <STRONG>o</STRONG> <STRONG>endwin</STRONG> calls other functions, many of which use
248 stdio or other library functions which are clear-
249 ly unsafe.
250
251 <STRONG>SIGTERM</STRONG>
252 This uses the same handler as <STRONG>SIGINT</STRONG>, with the same
253 limitations. It is not mentioned in X/Open Curses,
254 but is more suitable for this purpose than <STRONG>SIGQUIT</STRONG>
255 (which is used in debugging).
256
257 <STRONG>SIGTSTP</STRONG>
258 This handles the <EM>stop</EM> signal, used in job control.
259 When resuming the process, this implementation dis-
260 cards pending input with <STRONG>flushinput</STRONG> (see
261 <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>), and repaints the screen assuming that
262 it has been completely altered. It also updates the
263 saved terminal modes with <STRONG>def_shell_mode</STRONG> (see
264 <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>).
265
266 <STRONG>SIGWINCH</STRONG>
267 This handles the window-size changes which were ini-
268 tially ignored in the standardization efforts. The
269 handler sets a (signal-safe) variable which is later
270 tested in <STRONG>wgetch</STRONG> (see <STRONG><A HREF="curs_getch.3x.html">curs_getch(3x)</A></STRONG>). If <STRONG>keypad</STRONG> has
271 been enabled for the corresponding window, <STRONG>wgetch</STRONG> re-
272 turns the key symbol <STRONG>KEY_RESIZE</STRONG>. At the same time,
273 <STRONG>wgetch</STRONG> calls <STRONG>resizeterm</STRONG> to adjust the standard screen
274 <STRONG>stdscr</STRONG>, and update other data such as <STRONG>LINES</STRONG> and <STRONG>COLS</STRONG>.
275
276
277</PRE>
278<H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]279 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_kernel.3x.html">curs_kernel(3x)</A></STRONG>, <STRONG><A HREF="curs_refresh.3x.html">curs_refresh(3x)</A></STRONG>,
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]280 <STRONG><A HREF="curs_slk.3x.html">curs_slk(3x)</A></STRONG>, <STRONG><A HREF="curs_terminfo.3x.html">curs_terminfo(3x)</A></STRONG>, <STRONG><A HREF="curs_util.3x.html">curs_util(3x)</A></STRONG>, <STRONG>curs_vari-</STRONG>
281 <STRONG><A HREF="curs_variables.3x.html">ables(3x)</A></STRONG>.
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]282
283
284
285 <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>
286</PRE>
Steve Kondikae271bc2015-11-15 02:50:53 +0100[diff] [blame]287<div class="nav">
288<ul>
289<li><a href="#h2-NAME">NAME</a></li>
290<li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
291<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
292<ul>
293<li><a href="#h3-initscr">initscr</a></li>
294<li><a href="#h3-newterm">newterm</a></li>
295<li><a href="#h3-endwin">endwin</a></li>
296<li><a href="#h3-isendwin">isendwin</a></li>
297<li><a href="#h3-set_term">set_term</a></li>
298<li><a href="#h3-delscreen">delscreen</a></li>
299</ul>
300</li>
301<li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
302<li><a href="#h2-NOTES">NOTES</a></li>
303<li><a href="#h2-PORTABILITY">PORTABILITY</a>
304<ul>
305<li><a href="#h3-Differences">Differences</a></li>
306<li><a href="#h3-Unset-TERM-Variable">Unset TERM Variable</a></li>
307<li><a href="#h3-Signal-Handlers">Signal Handlers</a></li>
308</ul>
309</li>
310<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
311</ul>
312</div>
Amit Daniel Kachhape6a01f52011-07-20 11:45:59 +0530[diff] [blame]313</BODY>
314</HTML>