<!--
****************************************************************************
- * Copyright (c) 1998-2009,2010 Free Software Foundation, Inc. *
+ * Copyright (c) 1998-2010,2015 Free Software Foundation, Inc. *
* *
* Permission is hereby granted, free of charge, to any person obtaining a *
* copy of this software and associated documentation files (the *
* sale, use or other dealings in this Software without prior written *
* authorization. *
****************************************************************************
- * @Id: curs_color.3x,v 1.36 2014/11/16 00:44:29 tom Exp @
+ * @Id: curs_color.3x,v 1.38 2015/05/23 21:36:35 tom Exp @
-->
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01//EN">
<HTML>
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1">
</HEAD>
<BODY>
-<H1>curs_color 3x</H1>
-<HR>
+<H1 class="no-header">curs_color 3x</H1>
<PRE>
<STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG> <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
</PRE>
<H3><a name="h3-Overview">Overview</a></H3><PRE>
- <STRONG>curses</STRONG> support color attributes on terminals with that ca-
- pability. To use these routines <STRONG>start_color</STRONG> must be
+ <STRONG>curses</STRONG> supports color attributes on terminals with that
+ capability. To use these routines <STRONG>start_color</STRONG> must be
called, usually right after <STRONG>initscr</STRONG>. Colors are always
used in pairs (referred to as color-pairs). A color-pair
consists of a foreground color (for characters) and a
how a given color-pair is currently defined.
+</PRE>
+<H3><a name="h3-Color-Rendering">Color Rendering</a></H3><PRE>
+ The <STRONG>curses</STRONG> library combines these inputs to produce the
+ actual foreground and background colors shown on the
+ screen:
+
+ <STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>),
+
+ <STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and
+
+ <STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>).
+
+ Per-character and window attributes are usually set by a
+ parameter containing video attributes including a <STRONG>COL-</STRONG>
+ <STRONG>OR_PAIR</STRONG> value. Some functions such as <STRONG>wattr_set</STRONG> use a
+ separate parameter which is the color pair number.
+
+ The background character is a special case: it includes a
+ character value, just as if it were passed to <STRONG>waddch</STRONG>.
+
+ The <STRONG>curses</STRONG> library does the actual work of combining these
+ color pairs in an internal function called from <STRONG>waddch</STRONG>:
+
+ <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>blank</EM>, and it us-
+ es the special color pair 0,
+
+ <STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute.
+
+ <STRONG>o</STRONG> If the window attribute does not use color pair 0,
+ <STRONG>curses</STRONG> uses the color pair from the window at-
+ tribute.
+
+ <STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character.
+
+ <STRONG>o</STRONG> If the parameter passed to <STRONG>waddch</STRONG> is <EM>not</EM> <EM>blank</EM>, or it
+ does not use the special color pair 0, <STRONG>curses</STRONG> prefers
+ the color pair from the parameter, if it is nonzero.
+ Otherwise, it tries the window attribute next, and fi-
+ nally the background character.
+
+ Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those
+ do not combine its parameter with a color pair. Conse-
+ quently those calls use only the window attribute or the
+ background character.
+
+
</PRE>
<H3><a name="h3-Routine-Descriptions">Routine Descriptions</a></H3><PRE>
The <STRONG>start_color</STRONG> routine requires no arguments. It must be
- called if the programmer wants to use colors, and before
- any other color manipulation routine is called. It is
- good practice to call this routine right after <STRONG>initscr</STRONG>.
- <STRONG>start_color</STRONG> initializes eight basic colors (black, red,
- green, yellow, blue, magenta, cyan, and white), and two
- global variables, <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG> (respectively
- defining the maximum number of colors and color-pairs the
- terminal can support). It also restores the colors on the
- terminal to the values they had when the terminal was just
- turned on.
+ called if the programmer wants to use colors, and before
+ any other color manipulation routine is called. It is
+ good practice to call this routine right after <STRONG>initscr</STRONG>.
+ <STRONG>start_color</STRONG> does this:
+
+ <STRONG>o</STRONG> It initializes two global variables, <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
+ <STRONG>OR_PAIRS</STRONG> (respectively defining the maximum number of
+ colors and color-pairs the terminal can support).
+
+ <STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default
+ foreground and background colors. No other color
+ pairs are initialized.
+
+ <STRONG>o</STRONG> It restores the colors on the terminal to the values
+ they had when the terminal was just turned on.
+
+ <STRONG>o</STRONG> If the terminal supports the <STRONG>initc</STRONG> (<STRONG>initialize_color</STRONG>)
+ capability, <STRONG>start_color</STRONG> initializes its internal table
+ representing the red, green and blue components of the
+ color palette.
+
+ The components depend on whether the terminal uses CGA
+ (aka "ANSI") or HLS (i.e., the <STRONG>hls</STRONG> (<STRONG>hue_lightness_sat-</STRONG>
+ <STRONG>uration</STRONG>) capability is set). The table is initialized
+ first for eight basic colors (black, red, green, yel-
+ low, blue, magenta, cyan, and white), and after that
+ (if the terminal supports more than eight colors) the
+ components are initialized to <STRONG>1000</STRONG>.
+
+ <STRONG>start_color</STRONG> does not attempt to set the terminal's
+ color palette to match its built-in table. An appli-
+ cation may use <STRONG>init_color</STRONG> to alter the internal table
+ along with the terminal's color.
These limits apply to color values and color pairs. Val-
ues outside these limits are not legal, and may result in
<li><a href="#h2-DESCRIPTION">DESCRIPTION</a>
<ul>
<li><a href="#h3-Overview">Overview</a></li>
+<li><a href="#h3-Color-Rendering">Color Rendering</a></li>
<li><a href="#h3-Routine-Descriptions">Routine Descriptions</a></li>
<li><a href="#h3-Colors">Colors</a></li>
</ul>