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29 * @Id: curs_bkgd.3x,v 1.29 2019/07/13 21:01:06 tom Exp @
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41 <H1 class="no-header">curs_bkgd 3x</H1>
43 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG> <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
48 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
49 <STRONG>bkgdset</STRONG>, <STRONG>wbkgdset</STRONG>, <STRONG>bkgd</STRONG>, <STRONG>wbkgd</STRONG>, <STRONG>getbkgd</STRONG> - <STRONG>curses</STRONG> window background
53 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
54 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
56 <STRONG>void</STRONG> <STRONG>bkgdset(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
57 <STRONG>void</STRONG> <STRONG>wbkgdset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win,</EM> <EM>chtype</EM> <EM>ch</EM><STRONG>);</STRONG>
58 <STRONG>int</STRONG> <STRONG>bkgd(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
59 <STRONG>int</STRONG> <STRONG>wbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
60 <STRONG>chtype</STRONG> <STRONG>getbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
63 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
65 </PRE><H3><a name="h3-bkgdset">bkgdset</a></H3><PRE>
66 The <STRONG>bkgdset</STRONG> and <STRONG>wbkgdset</STRONG> routines manipulate the background of the
67 named window. The window background is a <STRONG>chtype</STRONG> consisting of any com-
68 bination of attributes (i.e., rendition) and a character. The
69 attribute part of the background is combined (OR'ed) with all non-blank
70 characters that are written into the window with <STRONG>waddch</STRONG>. Both the
71 character and attribute parts of the background are combined with the
72 blank characters. The background becomes a property of the character
73 and moves with the character through any scrolling and insert/delete
74 line/character operations.
76 To the extent possible on a particular terminal, the attribute part of
77 the background is displayed as the graphic rendition of the character
81 </PRE><H3><a name="h3-bkgd">bkgd</a></H3><PRE>
82 The <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> functions set the background property of the current
83 or specified window and then apply this setting to every character
84 position in that window. According to X/Open Curses, it should do
87 <STRONG>o</STRONG> The rendition of every character on the screen is changed to the
88 new background rendition.
90 <STRONG>o</STRONG> Wherever the former background character appears, it is changed to
91 the new background character.
93 Neither X/Open Curses nor the SVr4 manual pages give details about the
94 way the rendition of characters on the screen is updated when <STRONG>bkgd</STRONG> or
95 <STRONG>wbkgd</STRONG> is used to change the background character.
97 This implementation, like SVr4 curses, does not store the background
98 and window attribute contributions to each cell separately. It updates
99 the rendition by comparing the character, non-color attributes and col-
100 ors contained in the background. For each cell in the window, whether
103 <STRONG>o</STRONG> The library first compares the <EM>character</EM>, and if it matches the
104 current character part of the background, it replaces that with the
105 new background character.
107 <STRONG>o</STRONG> The library then checks if the cell uses color, i.e., its color
108 pair value is nonzero. If not, it simply replaces the attributes
109 and color pair in the cell with those from the new background char-
112 <STRONG>o</STRONG> If the cell uses color, and that matches the color in the current
113 background, the library removes attributes which may have come from
114 the current background and adds attributes from the new background.
115 It finishes by setting the cell to use the color from the new back-
118 <STRONG>o</STRONG> If the cell uses color, and that does not match the color in the
119 current background, the library updates only the non-color
120 attributes, first removing those which may have come from the cur-
121 rent background, and then adding attributes from the new back-
124 If the background's character value is zero, a space is assumed.
126 If the terminal does not support color, or if color has not been
127 started with <STRONG>start_color</STRONG>, the new background character's color
128 attribute will be ignored.
131 </PRE><H3><a name="h3-getbkgd">getbkgd</a></H3><PRE>
132 The <STRONG>getbkgd</STRONG> function returns the given window's current background
133 character/attribute pair.
136 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
137 These functions are described in the XSI Curses standard, Issue 4. It
138 specifies that <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return <STRONG>ERR</STRONG> on failure, but gives no fail-
141 The routines <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return the integer <STRONG>OK</STRONG>, unless the library
142 has not been initialized.
144 In contrast, the SVr4.0 manual says <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> may return <STRONG>OK</STRONG> "or a
145 non-negative integer if <STRONG>immedok</STRONG> is set", which refers to the return
146 value from <STRONG>wrefresh</STRONG> (used to implement the immediate repainting). The
147 SVr4 curses <STRONG>wrefresh</STRONG> returns the number of characters written to the
148 screen during the refresh. This implementation does not do that.
151 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
152 Note that <STRONG>bkgdset</STRONG> and <STRONG>bkgd</STRONG> may be macros.
154 X/Open Curses mentions that the character part of the background must
155 be a single-byte value. This implementation, like SVr4, checks to
156 ensure that, and will reuse the old background character if the check
160 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
161 These functions are described in the XSI Curses standard, Issue 4
165 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
166 <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_addch.3x.html">curs_addch(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_outopts.3x.html">curs_outopts(3x)</A></STRONG>
170 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
174 <li><a href="#h2-NAME">NAME</a></li>
175 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
176 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
178 <li><a href="#h3-bkgdset">bkgdset</a></li>
179 <li><a href="#h3-bkgd">bkgd</a></li>
180 <li><a href="#h3-getbkgd">getbkgd</a></li>
183 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
184 <li><a href="#h2-NOTES">NOTES</a></li>
185 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
186 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>