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| <H1 class="no-header">curs_bkgd 3x</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> |
| |
| |
| |
| |
| </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 |
| |
| |
| </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>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> |
| <STRONG>chtype</STRONG> <STRONG>getbkgd(WINDOW</STRONG> <STRONG>*</STRONG><EM>win</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 com- |
| bination 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. |
| |
| To the extent possible on a particular 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-bkgd">bkgd</a></H3><PRE> |
| The <STRONG>bkgd</STRONG> and <STRONG>wbkgd</STRONG> functions set the background property of the current |
| or specified window and then apply this setting to every character |
| position in that window. According to X/Open Curses, it should do |
| this: |
| |
| <STRONG>o</STRONG> The rendition of every character on the screen is changed to the |
| new background rendition. |
| |
| <STRONG>o</STRONG> Wherever the former background character appears, it is changed to |
| the new background character. |
| |
| Neither X/Open Curses nor the SVr4 manual pages give details about the |
| 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 col- |
| ors 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 char- |
| acter. |
| |
| <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 back- |
| ground. |
| |
| <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 cur- |
| rent background, and then adding attributes from the new back- |
| ground. |
| |
| If the background's character value is zero, 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 |
| 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 |
| 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 fail- |
| ure conditions. |
| |
| 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 |
| 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 |
| 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). |
| |
| |
| </PRE><H2><a name="h2-SEE-ALSO">SEE ALSO</a></H2><PRE> |
| <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> |
| |
| |
| |
| <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(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-bkgdset">bkgdset</a></li> |
| <li><a href="#h3-bkgd">bkgd</a></li> |
| <li><a href="#h3-getbkgd">getbkgd</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> |
| </div> |
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