* 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 1.35 2022/06/25 21:55:45 tom Exp @
-->
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</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
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
+ 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
+ The routines <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return the integer <STRONG>OK</STRONG>, unless the library
has not been initialized.
- 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
+ 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.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
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
+ 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.
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- These functions are described in the XSI Curses standard, Issue 4
+ These functions are described in the XSI Curses standard, Issue 4
(X/Open Curses).
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