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| <H1 class="no-header">curs_bkgrnd 3x 2024-04-20 ncurses 6.5 Library calls</H1> |
| <PRE> |
| <STRONG><A HREF="curs_bkgrnd.3x.html">curs_bkgrnd(3x)</A></STRONG> Library calls <STRONG><A HREF="curs_bkgrnd.3x.html">curs_bkgrnd(3x)</A></STRONG> |
| |
| |
| |
| |
| </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE> |
| <STRONG>bkgrnd</STRONG>, <STRONG>wbkgrnd</STRONG>, <STRONG>bkgrndset</STRONG>, <STRONG>wbkgrndset</STRONG>, <STRONG>getbkgrnd</STRONG>, <STRONG>wgetbkgrnd</STRONG> - |
| manipulate background of a <EM>curses</EM> window of wide characters |
| |
| |
| </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE> |
| <STRONG>#include</STRONG> <STRONG><curses.h></STRONG> |
| |
| <STRONG>int</STRONG> <STRONG>bkgrnd(const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| <STRONG>int</STRONG> <STRONG>wbkgrnd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| |
| <STRONG>void</STRONG> <STRONG>bkgrndset(const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| <STRONG>void</STRONG> <STRONG>wbkgrndset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>const</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| |
| <STRONG>int</STRONG> <STRONG>getbkgrnd(cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| <STRONG>int</STRONG> <STRONG>wgetbkgrnd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>cchar_t</STRONG> <STRONG>*</STRONG><EM>wch</EM><STRONG>);</STRONG> |
| |
| |
| </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE> |
| The <EM>background</EM> of a <EM>curses</EM> window (in the library's "wide" |
| configuration) is a <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> combining a set of attributes (see |
| <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>) with a complex character called the <EM>blank</EM> <EM>character.</EM> |
| |
| The blank character is a spacing character that populates a window's |
| character cells when their contents are erased without replacement. |
| The background's attributes are combined with all non-blank characters |
| written to the window, as with the <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG> and <STRONG><A HREF="curs_ins_wch.3x.html">wins_wch(3x)</A></STRONG> |
| families of functions. |
| |
| The blank character and attributes of the background combine with |
| characters written to the window as described below. The background |
| becomes a property of the character and moves with it through any |
| scrolling and insert/delete line/character operations. |
| |
| To the extent possible on a given terminal, the attribute part of the |
| background is displayed as the graphic rendition of the character put |
| on the screen. |
| |
| |
| </PRE><H3><a name="h3-bkgrnd_wbkgrnd">bkgrnd, wbkgrnd</a></H3><PRE> |
| <STRONG>bkgrnd</STRONG> and <STRONG>wbkgrnd</STRONG> set the background property of <STRONG>stdscr</STRONG> or the |
| specified window and then apply this setting to every character cell in |
| that window. |
| |
| <STRONG>o</STRONG> The rendition of every character in the window changes to the new |
| background rendition. |
| |
| <STRONG>o</STRONG> Wherever the former background character appears, it changes to the |
| new background character. |
| |
| <EM>ncurses</EM> updates the rendition of each character cell by comparing the |
| character, non-color attributes, and colors. The library applies to |
| following procedure to each cell in the window, whether or not it is |
| blank. |
| |
| <STRONG>o</STRONG> <EM>ncurses</EM> first compares the cell's character to the previously |
| specified blank character; if they match, <EM>ncurses</EM> writes the new |
| blank character to the cell. |
| |
| <STRONG>o</STRONG> <EM>ncurses</EM> then checks if the cell uses color, that is, its color pair |
| value is nonzero. If not, it simply replaces the attributes and |
| color pair in the cell with those from the new background |
| character. |
| |
| <STRONG>o</STRONG> If the cell uses color, and its background color matches that of |
| the current window background, <EM>ncurses</EM> removes attributes that may |
| have come from the current background and adds those from the new |
| background. It finishes by setting the cell's background to use |
| the new window background color. |
| |
| <STRONG>o</STRONG> If the cell uses color, and its background color does not match |
| that of the current window background, <EM>ncurses</EM> updates only the |
| non-color attributes, first removing those that may have come from |
| the current background, and then adding attributes from the new |
| background. |
| |
| <EM>ncurses</EM> treats a background character value of zero (0) as a blank |
| character. |
| |
| If the terminal does not support color, or if color has not been |
| initialized with <STRONG><A HREF="curs_color.3x.html">start_color(3x)</A></STRONG>, <EM>ncurses</EM> ignores the new background |
| character's color attribute. |
| |
| |
| </PRE><H3><a name="h3-bkgrndset_wbkgrndset">bkgrndset, wbkgrndset</a></H3><PRE> |
| <STRONG>bkgrndset</STRONG> and <STRONG>wbkgrndset</STRONG> manipulate the background of the applicable |
| window, without updating the character cells as <STRONG>bkgrnd</STRONG> and <STRONG>wbkgrnd</STRONG> do; |
| only future writes reflect the updated background. |
| |
| |
| </PRE><H3><a name="h3-getbkgrnd_wgetbkgrnd">getbkgrnd, wgetbkgrnd</a></H3><PRE> |
| The <STRONG>getbkgrnd</STRONG> and <STRONG>wgetbkgrnd</STRONG> functions obtain the background character |
| and attribute pair of <STRONG>stdscr</STRONG> or the specified window and store it via |
| the <EM>wch</EM> pointer. |
| |
| |
| </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE> |
| <STRONG>bkgrndset</STRONG> and <STRONG>wbkgrndset</STRONG> do not return a value. |
| |
| The other functions return <STRONG>ERR</STRONG> upon failure and <STRONG>OK</STRONG> upon success. In |
| <EM>ncurses</EM>, failure occurs if |
| |
| <STRONG>o</STRONG> a <EM>WINDOW</EM> pointer <EM>win</EM> is null, or |
| |
| <STRONG>o</STRONG> a <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> pointer <EM>wch</EM> is null. |
| |
| |
| </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE> |
| <STRONG>bkgrnd</STRONG>, <STRONG>bkgrndset</STRONG>, and <STRONG>getbkgrnd</STRONG> may be implemented as macros. |
| |
| Unlike their counterparts in the non-"wide" configuration of <EM>ncurses</EM>, |
| <STRONG>getbkgrnd</STRONG> and <STRONG>wgetbkgrnd</STRONG> supply the background character and attribute |
| in a modifiable <EM>cchar</EM><STRONG>_</STRONG><EM>t</EM> parameter, not as the return value. |
| |
| |
| </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE> |
| X/Open Curses, Issue 4 describes these functions. It specifies no |
| error conditions for them. |
| |
| X/Open Curses does not provide details of how the rendition is updated. |
| This implementation follows the approach used in SVr4 <EM>curses</EM>. |
| |
| |
| </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> |
| <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG> describes the corresponding functions in the non-"wide" |
| configuration of <EM>ncurses</EM>. |
| |
| <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_add_wch.3x.html">curs_add_wch(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG> |
| |
| |
| |
| ncurses 6.5 2024-04-20 <STRONG><A HREF="curs_bkgrnd.3x.html">curs_bkgrnd(3x)</A></STRONG> |
| </PRE> |
| <div class="nav"> |
| <ul> |
| <li><a href="#h2-NAME">NAME</a></li> |
| <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li> |
| <li><a href="#h2-DESCRIPTION">DESCRIPTION</a> |
| <ul> |
| <li><a href="#h3-bkgrnd_wbkgrnd">bkgrnd, wbkgrnd</a></li> |
| <li><a href="#h3-bkgrndset_wbkgrndset">bkgrndset, wbkgrndset</a></li> |
| <li><a href="#h3-getbkgrnd_wgetbkgrnd">getbkgrnd, wgetbkgrnd</a></li> |
| </ul> |
| </li> |
| <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li> |
| <li><a href="#h2-NOTES">NOTES</a></li> |
| <li><a href="#h2-PORTABILITY">PORTABILITY</a></li> |
| <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li> |
| </ul> |
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