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30 * @Id: curs_bkgd.3x,v 1.30 2020/02/02 23:34:34 tom Exp @
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42 <H1 class="no-header">curs_bkgd 3x</H1>
44 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG> <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
49 </PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
50 <STRONG>bkgdset</STRONG>, <STRONG>wbkgdset</STRONG>, <STRONG>bkgd</STRONG>, <STRONG>wbkgd</STRONG>, <STRONG>getbkgd</STRONG> - <STRONG>curses</STRONG> window background
54 </PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
55 <STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
57 <STRONG>void</STRONG> <STRONG>bkgdset(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
58 <STRONG>void</STRONG> <STRONG>wbkgdset(WINDOW</STRONG> <STRONG>*</STRONG><EM>win,</EM> <EM>chtype</EM> <EM>ch</EM><STRONG>);</STRONG>
59 <STRONG>int</STRONG> <STRONG>bkgd(chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
60 <STRONG>int</STRONG> <STRONG>wbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>,</STRONG> <STRONG>chtype</STRONG> <EM>ch</EM><STRONG>);</STRONG>
61 <STRONG>chtype</STRONG> <STRONG>getbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</EM><STRONG>);</STRONG>
64 </PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
66 </PRE><H3><a name="h3-bkgdset">bkgdset</a></H3><PRE>
67 The <STRONG>bkgdset</STRONG> and <STRONG>wbkgdset</STRONG> routines manipulate the background of the
68 named window. The window background is a <STRONG>chtype</STRONG> consisting of any com-
69 bination of attributes (i.e., rendition) and a character. The
70 attribute part of the background is combined (OR'ed) with all non-blank
71 characters that are written into the window with <STRONG>waddch</STRONG>. Both the
72 character and attribute parts of the background are combined with the
73 blank characters. The background becomes a property of the character
74 and moves with the character through any scrolling and insert/delete
75 line/character operations.
77 To the extent possible on a particular terminal, the attribute part of
78 the background is displayed as the graphic rendition of the character
82 </PRE><H3><a name="h3-bkgd">bkgd</a></H3><PRE>
83 The <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> functions set the background property of the current
84 or specified window and then apply this setting to every character
85 position in that window. According to X/Open Curses, it should do
88 <STRONG>o</STRONG> The rendition of every character on the screen is changed to the
89 new background rendition.
91 <STRONG>o</STRONG> Wherever the former background character appears, it is changed to
92 the new background character.
94 Neither X/Open Curses nor the SVr4 manual pages give details about the
95 way the rendition of characters on the screen is updated when <STRONG>bkgd</STRONG> or
96 <STRONG>wbkgd</STRONG> is used to change the background character.
98 This implementation, like SVr4 curses, does not store the background
99 and window attribute contributions to each cell separately. It updates
100 the rendition by comparing the character, non-color attributes and col-
101 ors contained in the background. For each cell in the window, whether
104 <STRONG>o</STRONG> The library first compares the <EM>character</EM>, and if it matches the
105 current character part of the background, it replaces that with the
106 new background character.
108 <STRONG>o</STRONG> The library then checks if the cell uses color, i.e., its color
109 pair value is nonzero. If not, it simply replaces the attributes
110 and color pair in the cell with those from the new background char-
113 <STRONG>o</STRONG> If the cell uses color, and that matches the color in the current
114 background, the library removes attributes which may have come from
115 the current background and adds attributes from the new background.
116 It finishes by setting the cell to use the color from the new back-
119 <STRONG>o</STRONG> If the cell uses color, and that does not match the color in the
120 current background, the library updates only the non-color
121 attributes, first removing those which may have come from the cur-
122 rent background, and then adding attributes from the new back-
125 If the background's character value is zero, a space is assumed.
127 If the terminal does not support color, or if color has not been
128 started with <STRONG>start_color</STRONG>, the new background character's color
129 attribute will be ignored.
132 </PRE><H3><a name="h3-getbkgd">getbkgd</a></H3><PRE>
133 The <STRONG>getbkgd</STRONG> function returns the given window's current background
134 character/attribute pair.
137 </PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
138 These functions are described in the XSI Curses standard, Issue 4. It
139 specifies that <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return <STRONG>ERR</STRONG> on failure, but gives no fail-
142 The routines <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> return the integer <STRONG>OK</STRONG>, unless the library
143 has not been initialized.
145 In contrast, the SVr4.0 manual says <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> may return <STRONG>OK</STRONG> "or a
146 non-negative integer if <STRONG>immedok</STRONG> is set", which refers to the return
147 value from <STRONG>wrefresh</STRONG> (used to implement the immediate repainting). The
148 SVr4 curses <STRONG>wrefresh</STRONG> returns the number of characters written to the
149 screen during the refresh. This implementation does not do that.
152 </PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
153 Note that <STRONG>bkgdset</STRONG> and <STRONG>bkgd</STRONG> may be macros.
155 X/Open Curses mentions that the character part of the background must
156 be a single-byte value. This implementation, like SVr4, checks to
157 ensure that, and will reuse the old background character if the check
161 </PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
162 These functions are described in the XSI Curses standard, Issue 4
166 </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE>
167 <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>
171 <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>
175 <li><a href="#h2-NAME">NAME</a></li>
176 <li><a href="#h2-SYNOPSIS">SYNOPSIS</a></li>
177 <li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
179 <li><a href="#h3-bkgdset">bkgdset</a></li>
180 <li><a href="#h3-bkgd">bkgd</a></li>
181 <li><a href="#h3-getbkgd">getbkgd</a></li>
184 <li><a href="#h2-RETURN-VALUE">RETURN VALUE</a></li>
185 <li><a href="#h2-NOTES">NOTES</a></li>
186 <li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
187 <li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>