<!--
****************************************************************************
- * Copyright 2018-2021,2022 Thomas E. Dickey *
+ * Copyright 2018-2022,2023 Thomas E. Dickey *
* Copyright 1998-2015,2017 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: curs_bkgd.3x,v 1.34 2022/02/12 20:06:41 tom Exp @
+ * @Id: curs_bkgd.3x,v 1.51 2023/12/02 21:02:44 tom Exp @
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>
<HEAD>
<meta http-equiv="Content-Type" content="text/html; charset=us-ascii">
<meta name="generator" content="Manpage converted by man2html - see https://invisible-island.net/scripts/readme.html#others_scripts">
-<TITLE>curs_bkgd 3x</TITLE>
+<TITLE>curs_bkgd 3x 2023-12-02 ncurses 6.4 Library calls</TITLE>
<link rel="author" href="mailto:bug-ncurses@gnu.org">
</HEAD>
<BODY>
-<H1 class="no-header">curs_bkgd 3x</H1>
+<H1 class="no-header">curs_bkgd 3x 2023-12-02 ncurses 6.4 Library calls</H1>
<PRE>
-<STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
<STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
+<STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
Library calls <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
- <STRONG>bkgdset</STRONG>, <STRONG>wbkgdset</STRONG>, <STRONG>bkgd</STRONG>, <STRONG>wbkgd</STRONG>, <STRONG>getbkgd</STRONG> - <STRONG>curses</STRONG> window background
- manipulation routines
+ <STRONG>bkgdset</STRONG>, <STRONG>wbkgdset</STRONG>, <STRONG>bkgd</STRONG>, <STRONG>wbkgd</STRONG>, <STRONG>getbkgd</STRONG> - manipulate background of a
+ <EM>curses</EM> window of characters
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
<STRONG>void</STRONG> <STRONG>bkgdset(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
- <STRONG>void</STRONG> <STRONG>wbkgdset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win,</EM> <EM>chtype</EM> <EM>ch</EM><STRONG>);</STRONG>
+ <STRONG>void</STRONG> <STRONG>wbkgdset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>bkgd(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
<STRONG>int</STRONG> <STRONG>wbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
</PRE><H3><a name="h3-bkgdset">bkgdset</a></H3><PRE>
- The <STRONG>bkgdset</STRONG> and <STRONG>wbkgdset</STRONG> routines manipulate the background of the
- named window. The window background is a <STRONG>chtype</STRONG> consisting of any
- combination of attributes (i.e., rendition) and a character. The
- attribute part of the background is combined (OR'ed) with all non-blank
- characters that are written into the window with <STRONG>waddch</STRONG>. Both the
- character and attribute parts of the background are combined with the
- blank characters. The background becomes a property of the character
- and moves with the character through any scrolling and insert/delete
- line/character operations.
+ The <STRONG>bkgdset</STRONG> and <STRONG>wbkgdset</STRONG> routines set the <EM>background</EM> for a window. A
+ window's background is a <STRONG>chtype</STRONG> consisting of any combination of
+ attributes (i.e., rendition) and a character:
+
+ <STRONG>o</STRONG> The attribute part of the background is combined (OR'ed) with all
+ non-blank characters that are written into the window with <STRONG>waddch</STRONG>.
+
+ <STRONG>o</STRONG> Both the character and attribute parts of the background are
+ combined with blank characters that are written into the window.
+
+ The background becomes a property of each character and moves with the
+ character through any scrolling and insert/delete line/character
+ operations.
To the extent possible on a particular terminal, the attribute part of
the background is displayed as the graphic rendition of the character
way the rendition of characters on the screen is updated when <STRONG>bkgd</STRONG> or
<STRONG>wbkgd</STRONG> is used to change the background character.
- This implementation, like SVr4 curses, does not store the background
- and window attribute contributions to each cell separately. It updates
- the rendition by comparing the character, non-color attributes and
- colors contained in the background. For each cell in the window,
- whether or not it is blank:
+ <EM>ncurses</EM>, like SVr4 <EM>curses</EM>, does not store the background and window
+ attribute contributions to each cell separately. It updates the
+ rendition by comparing the character, non-color attributes and colors
+ contained in the background. For each cell in the window, whether or
+ not it is blank:
<STRONG>o</STRONG> The library first compares the <EM>character</EM>, and if it matches the
current character part of the background, it replaces that with the
new background character.
- <STRONG>o</STRONG> The library then checks if the cell uses color, i.e., 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
+ When <STRONG>bkgdset</STRONG> is used to set the background character, that does not
+ update each cell in the window. A subsequent call to <STRONG>bkgd</STRONG> will
+ only modify the <EM>character</EM> in cells which match the current
+ background character.
+
+ <STRONG>o</STRONG> The library then checks if the cell uses color, i.e., 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 that matches the color in the current
+ <STRONG>o</STRONG> If the cell uses color, and that matches the color in the current
background, the library removes attributes which may have come from
the current background and adds attributes from the new background.
- It finishes by setting the cell to use the color from the new
+ It finishes by setting the cell to use the color from the new
background.
- <STRONG>o</STRONG> If the cell uses color, and that does not match the color in the
- current background, the library updates only the non-color
- attributes, first removing those which may have come from the
+ <STRONG>o</STRONG> If the cell uses color, and that does not match the color in the
+ current background, the library updates only the non-color
+ attributes, first removing those which may have come from the
current background, and then adding attributes from the new
background.
- If the background's character value is zero, a space is assumed.
+ If the background's character value is zero (0), a space is assumed.
- If the terminal does not support color, or if color has not been
- started with <STRONG>start_color</STRONG>, the new background character's color
+ If the terminal does not support color, or if color has not been
+ started with <STRONG>start_color</STRONG>, the new background character's color
attribute will be ignored.
</PRE><H3><a name="h3-getbkgd">getbkgd</a></H3><PRE>
- The <STRONG>getbkgd</STRONG> function returns the given window's current background
+ The <STRONG>getbkgd</STRONG> function returns the given window's current background
character/attribute pair.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
- These functions are described in the XSI Curses standard, Issue 4. It
- specifies that <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return <STRONG>ERR</STRONG> on failure, but gives no
- failure conditions.
-
- The routines <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return the integer <STRONG>OK</STRONG>, unless the library
- has not been initialized.
+ Functions returning an <EM>int</EM> return <STRONG>OK</STRONG> on success. <STRONG>bkgd</STRONG> returns <STRONG>ERR</STRONG> if
+ the library has not been initialized. <STRONG>wbkgd</STRONG> and <STRONG>getbkgd</STRONG> return <STRONG>ERR</STRONG> if
+ the <EM>WINDOW</EM> pointer argument is null.
In contrast, the SVr4.0 manual says <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> may return <STRONG>OK</STRONG> "or a
non-negative integer if <STRONG>immedok</STRONG> is set", which refers to the return
- value from <STRONG>wrefresh</STRONG> (used to implement the immediate repainting). The
- SVr4 curses <STRONG>wrefresh</STRONG> returns the number of characters written to the
- screen during the refresh. This implementation does not do that.
+ value from <STRONG>wrefresh</STRONG> (used to implement the immediate repainting). SVr4
+ <EM>curses</EM> <STRONG>wrefresh</STRONG> returns the number of characters written to the screen
+ during the refresh. <EM>ncurses</EM> does not do that.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
+ Unusually, there is no <STRONG>wgetbkgd</STRONG> function; <STRONG>getbkgd</STRONG> behaves as one would
+ expect <STRONG>wgetbkgd</STRONG> to, accepting a <EM>WINDOW</EM> pointer argument.
+
Note that <STRONG>bkgdset</STRONG> and <STRONG>bkgd</STRONG> may be macros.
- X/Open Curses mentions that the character part of the background must
- be a single-byte value. This implementation, like SVr4, checks to
- ensure that, and will reuse the old background character if the check
- fails.
+ X/Open Curses mentions that the character part of the background must
+ be a single-byte value. <EM>ncurses</EM>, like SVr4 <EM>curses</EM>, checks to ensure
+ that, and will reuse the old background character if the check fails.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- These functions are described in the XSI Curses standard, Issue 4
- (X/Open Curses).
+ These functions are described in the XSI Curses standard, Issue 4. It
+ specifies that <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return <STRONG>ERR</STRONG> on failure, but gives no
+ failure conditions.
</PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
-
<STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
+
ncurses 6.4 2023-12-02 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
projects / ncurses.git / blobdiff