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-<H1 class="no-header">curs_color 3x</H1>
+<H1 class="no-header">curs_color 3x 2024-04-20 ncurses 6.4 Library calls</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>
+<STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
Library calls <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
</PRE><H2><a name="h2-NAME">NAME</a></H2><PRE>
- <STRONG>start_color</STRONG>, <STRONG>has_colors</STRONG>, <STRONG>can_change_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>,
- <STRONG>init_extended_pair</STRONG>, <STRONG>init_extended_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>,
- <STRONG>extended_color_content</STRONG>, <STRONG>extended_pair_content</STRONG>, <STRONG>reset_color_pairs</STRONG>,
- <STRONG>COLOR_PAIR</STRONG>, <STRONG>PAIR_NUMBER</STRONG> - <STRONG>curses</STRONG> color manipulation routines
+ <STRONG>start_color</STRONG>, <STRONG>has_colors</STRONG>, <STRONG>can_change_color</STRONG>, <STRONG>init_pair</STRONG>, <STRONG>init_color</STRONG>,
+ <STRONG>init_extended_pair</STRONG>, <STRONG>init_extended_color</STRONG>, <STRONG>color_content</STRONG>, <STRONG>pair_content</STRONG>,
+ <STRONG>extended_color_content</STRONG>, <STRONG>extended_pair_content</STRONG>, <STRONG>reset_color_pairs</STRONG>,
+ <STRONG>COLOR_PAIR</STRONG>, <STRONG>PAIR_NUMBER</STRONG>, <STRONG>COLORS</STRONG>, <STRONG>COLOR_PAIRS</STRONG>, <STRONG>COLOR_BLACK</STRONG>, <STRONG>COLOR_RED</STRONG>,
+ <STRONG>COLOR_GREEN</STRONG>, <STRONG>COLOR_YELLOW</STRONG>, <STRONG>COLOR_BLUE</STRONG>, <STRONG>COLOR_MAGENTA</STRONG>, <STRONG>COLOR_CYAN</STRONG>,
+ <STRONG>COLOR_WHITE</STRONG> - manipulate terminal colors with <EM>curses</EM>
</PRE><H2><a name="h2-SYNOPSIS">SYNOPSIS</a></H2><PRE>
<STRONG>#include</STRONG> <STRONG><curses.h></STRONG>
+ <EM>/*</EM> <EM>variables</EM> <EM>*/</EM>
+ <STRONG>int</STRONG> <STRONG>COLOR_PAIRS;</STRONG>
+ <STRONG>int</STRONG> <STRONG>COLORS;</STRONG>
+
<STRONG>int</STRONG> <STRONG>start_color(void);</STRONG>
<STRONG>bool</STRONG> <STRONG>has_colors(void);</STRONG>
<STRONG>bool</STRONG> <STRONG>can_change_color(void);</STRONG>
- <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>f,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
- <STRONG>int</STRONG> <STRONG>init_color(short</STRONG> <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>r,</STRONG> <STRONG>short</STRONG> <STRONG>g,</STRONG> <STRONG>short</STRONG> <STRONG>b);</STRONG>
- /* extensions */
- <STRONG>int</STRONG> <STRONG>init_extended_pair(int</STRONG> <STRONG>pair,</STRONG> <STRONG>int</STRONG> <STRONG>f,</STRONG> <STRONG>int</STRONG> <STRONG>b);</STRONG>
- <STRONG>int</STRONG> <STRONG>init_extended_color(int</STRONG> <STRONG>color,</STRONG> <STRONG>int</STRONG> <STRONG>r,</STRONG> <STRONG>int</STRONG> <STRONG>g,</STRONG> <STRONG>int</STRONG> <STRONG>b);</STRONG>
+ <STRONG>int</STRONG> <STRONG>init_pair(short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>f</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>b</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>init_color(short</STRONG> <EM>color</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>r</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>g</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <EM>b</EM><STRONG>);</STRONG>
+ <EM>/*</EM> <EM>extensions</EM> <EM>*/</EM>
+ <STRONG>int</STRONG> <STRONG>init_extended_pair(int</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>f</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>b</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>init_extended_color(int</STRONG> <EM>color</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>r</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>g</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <EM>b</EM><STRONG>);</STRONG>
- <STRONG>int</STRONG> <STRONG>color_content(short</STRONG> <STRONG>color,</STRONG> <STRONG>short</STRONG> <STRONG>*r,</STRONG> <STRONG>short</STRONG> <STRONG>*g,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
- <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <STRONG>pair,</STRONG> <STRONG>short</STRONG> <STRONG>*f,</STRONG> <STRONG>short</STRONG> <STRONG>*b);</STRONG>
- /* extensions */
- <STRONG>int</STRONG> <STRONG>extended_color_content(int</STRONG> <STRONG>color,</STRONG> <STRONG>int</STRONG> <STRONG>*r,</STRONG> <STRONG>int</STRONG> <STRONG>*g,</STRONG> <STRONG>int</STRONG> <STRONG>*b);</STRONG>
- <STRONG>int</STRONG> <STRONG>extended_pair_content(int</STRONG> <STRONG>pair,</STRONG> <STRONG>int</STRONG> <STRONG>*f,</STRONG> <STRONG>int</STRONG> <STRONG>*b);</STRONG>
+ <STRONG>int</STRONG> <STRONG>color_content(short</STRONG> <EM>color</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>r</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>g</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>b</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>pair_content(short</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>f</EM><STRONG>,</STRONG> <STRONG>short</STRONG> <STRONG>*</STRONG><EM>b</EM><STRONG>);</STRONG>
+ <EM>/*</EM> <EM>extensions</EM> <EM>*/</EM>
+ <STRONG>int</STRONG> <STRONG>extended_color_content(int</STRONG> <EM>color</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>*</STRONG><EM>r</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>*</STRONG><EM>g</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>*</STRONG><EM>b</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>extended_pair_content(int</STRONG> <EM>pair</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>*</STRONG><EM>f</EM><STRONG>,</STRONG> <STRONG>int</STRONG> <STRONG>*</STRONG><EM>b</EM><STRONG>);</STRONG>
- /* extensions */
+ <EM>/*</EM> <EM>extension</EM> <EM>*/</EM>
<STRONG>void</STRONG> <STRONG>reset_color_pairs(void);</STRONG>
- <STRONG>int</STRONG> <STRONG>COLOR_PAIR(int</STRONG> <STRONG>n);</STRONG>
- <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</EM><STRONG>);</STRONG>
+ <STRONG>int</STRONG> <STRONG>COLOR_PAIR(int</STRONG> <EM>n</EM><STRONG>);</STRONG>
+ <STRONG>PAIR_NUMBER(int</STRONG> <EM>attr</EM><STRONG>);</STRONG>
</PRE><H2><a name="h2-DESCRIPTION">DESCRIPTION</a></H2><PRE>
</PRE><H3><a name="h3-Overview">Overview</a></H3><PRE>
- <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
- background color (for the blank field on which the characters are dis-
- played). A programmer initializes a color-pair with the routine
- <STRONG>init_pair</STRONG>. After it has been initialized, <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>) can be used to
- convert the pair to a video attribute.
+ <EM>curses</EM> supports color attributes on terminals with that capability.
+ Call <STRONG>start_color</STRONG> (typically right after <STRONG><A HREF="curs_initscr.3x.html">initscr(3x)</A></STRONG>) to enable this
+ feature. Colors are always used in pairs. A <EM>color</EM> <EM>pair</EM> couples a
+ foreground color for characters with a background color for the blank
+ field on which characters are rendered. <STRONG>init_pair</STRONG> initializes a color
+ pair. The macro <STRONG>COLOR_PAIR</STRONG>(<EM>n</EM>) can then convert the pair to a video
+ attribute.
- If a terminal is capable of redefining colors, the programmer can use
- the routine <STRONG>init_color</STRONG> to change the definition of a color. The rou-
- tines <STRONG>has_colors</STRONG> and <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>, depending
- on whether the terminal has color capabilities and whether the program-
- mer can change the colors. The routine <STRONG>color_content</STRONG> allows a program-
- mer to extract the amounts of red, green, and blue components in an
- initialized color. The routine <STRONG>pair_content</STRONG> allows a programmer to
- find out how a given color-pair is currently defined.
+ If a terminal has the relevant capability, <STRONG>init_color</STRONG> permits
+ (re)definition of a color. <STRONG>has_colors</STRONG> and <STRONG>can_change_color</STRONG> return <STRONG>TRUE</STRONG>
+ or <STRONG>FALSE</STRONG>, depending on whether the terminal has color capability and
+ whether the programmer can change the colors. <STRONG>color_content</STRONG> permits
+ extraction of the red, green, and blue components of an initialized
+ color. <STRONG>pair_content</STRONG> permits discovery of a color pair's current
+ definition.
-</PRE><H3><a name="h3-
Color-Rendering">Color Rendering</a></H3><PRE>
- The <STRONG>curses</STRONG> library combines these inputs to produce the actual fore-
- ground and background colors shown on the screen:
+</PRE><H3><a name="h3-
Rendering">Rendering</a></H3><PRE>
+ <EM>curses</EM> combines the following data to render a character cell. Any of
+ them can include color information.
- <STRONG>o</STRONG> per-character video attributes (e.g., via <STRONG>waddch</STRONG>),
+ <STRONG>o</STRONG> <EM>curses</EM> character attributes, as from <STRONG><A HREF="curs_addch.3x.html">waddch(3x)</A></STRONG> or <STRONG><A HREF="curs_add_wch.3x.html">wadd_wch(3x)</A></STRONG>
- <STRONG>o</STRONG> the window attribute (e.g., by <STRONG>wattrset</STRONG>), and
+ <STRONG>o</STRONG> window attributes, as from <STRONG><A HREF="curs_attr.3x.html">wattrset(3x)</A></STRONG> or <STRONG><A HREF="curs_attr.3x.html">wattr_set(3x)</A></STRONG>
- <STRONG>o</STRONG> the background character (e.g., <STRONG>wbkgdset</STRONG>).
+ <STRONG>o</STRONG> window background character attributes, as from <STRONG><A HREF="curs_bkgd.3x.html">wbkgdset(3x)</A></STRONG> or
+ <STRONG><A HREF="curs_bkgrnd.3x.html">wbkgrndset(3x)</A></STRONG>
- Per-character and window attributes are usually set by a parameter con-
- taining video attributes including a color pair value. Some functions
- such as <STRONG>wattr_set</STRONG> use a separate parameter which is the color pair num-
- ber.
+ Per-character and window attributes are usually set through a function
+ parameter containing attributes including a color pair value. Some
+ functions, such as <STRONG>wattr_set</STRONG>, use a separate color pair number
+ parameter.
- The background character is a special case: it includes a character
- value, just as if it were passed to <STRONG>waddch</STRONG>.
+ The background character is a special case: it includes a character
+ code, just as if it were passed to <STRONG>waddch</STRONG>.
- The <STRONG>curses</STRONG> library does the actual work of combining these color pairs
+ The <EM>curses</EM> 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 uses the special
color pair 0,
- <STRONG>o</STRONG> <STRONG>curses</STRONG> next checks the window attribute.
+ <STRONG>o</STRONG> <EM>curses</EM> next checks the window attribute.
- <STRONG>o</STRONG> If the window attribute does not use color pair 0, <STRONG>curses</STRONG> uses
+ <STRONG>o</STRONG> If the window attribute does not use color pair 0, <EM>curses</EM> uses
the color pair from the window attribute.
- <STRONG>o</STRONG> Otherwise, <STRONG>curses</STRONG> uses the background character.
+ <STRONG>o</STRONG> Otherwise, <EM>curses</EM> 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 at-
- tribute next, and finally 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, <EM>curses</EM> prefers the color pair from the
+ parameter, if it is nonzero. Otherwise, it tries the window
+ attribute next, and finally the background character.
- Some <STRONG>curses</STRONG> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those do not com-
- bine its parameter with a color pair. Consequently those calls use on-
- ly the window attribute or the background character.
+ Some <EM>curses</EM> functions such as <STRONG>wprintw</STRONG> call <STRONG>waddch</STRONG>. Those do not
+ combine its parameter with a color pair. Consequently those calls use
+ only the window attribute or the background character.
</PRE><H2><a name="h2-CONSTANTS">CONSTANTS</a></H2><PRE>
In <STRONG><curses.h></STRONG> the following macros are defined. These are the standard
- colors (ISO-6429). <STRONG>curses</STRONG> also assumes that <STRONG>COLOR_BLACK</STRONG> is the default
+ colors (ISO-6429). <EM>curses</EM> also assumes that <STRONG>COLOR_BLACK</STRONG> is the default
background color for all terminals.
<STRONG>COLOR_BLACK</STRONG>
<STRONG>COLOR_CYAN</STRONG>
<STRONG>COLOR_WHITE</STRONG>
- Some terminals support more than the eight (8) "ANSI" colors. There
+ Some terminals support more than the eight (8) "ANSI" colors. There
are no standard names for those additional colors.
</PRE><H2><a name="h2-VARIABLES">VARIABLES</a></H2><PRE>
</PRE><H3><a name="h3-COLORS">COLORS</a></H3><PRE>
- is initialized by <STRONG>start_color</STRONG> to the maximum number of colors the ter-
- minal can support.
+ is initialized by <STRONG>start_color</STRONG> to the maximum number of colors the
+ terminal can support.
</PRE><H3><a name="h3-COLOR_PAIRS">COLOR_PAIRS</a></H3><PRE>
- is initialized by <STRONG>start_color</STRONG> to the maximum number of color pairs the
- terminal can support.
+ is initialized by <STRONG>start_color</STRONG> to the maximum number of color pairs the
+ terminal can support. Often, its value is the product <STRONG>COLORS</STRONG> x <STRONG>COLORS</STRONG>,
+ but this is not always true.
+
+ <STRONG>o</STRONG> A few terminals use the HLS color space (see <STRONG>start_color</STRONG> below),
+ ignoring this rule; and
+
+ <STRONG>o</STRONG> terminals supporting a large number of colors are limited to the
+ number of color pairs that a <EM>signed</EM> <EM>short</EM> value can represent.
</PRE><H2><a name="h2-FUNCTIONS">FUNCTIONS</a></H2><PRE>
</PRE><H3><a name="h3-start_color">start_color</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 manipu-
- lation routine is called. It is good practice to call this routine
- right after <STRONG>initscr</STRONG>. <STRONG>start_color</STRONG> does this:
+ 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>COLOR_PAIRS</STRONG> (re-
- spectively defining the maximum number of colors and color-pairs
+ <STRONG>o</STRONG> It initializes 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).
<STRONG>o</STRONG> It initializes the special color pair <STRONG>0</STRONG> to the default foreground
initial eight colors.
<STRONG>start_color</STRONG> does not attempt to set the terminal's color palette to
- match its built-in table. An application may use <STRONG>init_color</STRONG> to al-
- ter the internal table along with the terminal's color.
+ match its built-in table. An application 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. Values outside
- these limits are not legal, and may result in a runtime error:
+ these limits are not valid, and may result in a runtime error:
- <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_colors</STRONG> capabili-
- ty, (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
+ <STRONG>o</STRONG> <STRONG>COLORS</STRONG> corresponds to the terminal database's <STRONG>max_colors</STRONG>
+
capability, (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
- <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COLORS-1</STRONG>, inclu-
- sive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
+ <STRONG>o</STRONG> color values are expected to be in the range <STRONG>0</STRONG> to <STRONG>COLORS-1</STRONG>,
+ inclusive (including <STRONG>0</STRONG> and <STRONG>COLORS-1</STRONG>).
<STRONG>o</STRONG> a special color value <STRONG>-1</STRONG> is used in certain extended functions to
denote the <EM>default</EM> <EM>color</EM> (see <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>).
- <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's <STRONG>max_pairs</STRONG> capa-
- bility, (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
+ <STRONG>o</STRONG> <STRONG>COLOR_PAIRS</STRONG> corresponds to the terminal database's <STRONG>max_pairs</STRONG>
+
capability, (see <STRONG><A HREF="terminfo.5.html">terminfo(5)</A></STRONG>).
- <STRONG>o</STRONG> legal color pair values are in the range <STRONG>1</STRONG> to <STRONG>COLOR_PAIRS-1</STRONG>, inclu-
- sive.
+ <STRONG>o</STRONG> valid color pair values are in the range <STRONG>1</STRONG> to <STRONG>COLOR_PAIRS-1</STRONG>,
+ inclusive.
<STRONG>o</STRONG> color pair <STRONG>0</STRONG> is special; it denotes "no color".
- Color pair <STRONG>0</STRONG> is assumed to be white on black, but is actually what-
- ever the terminal implements before color is initialized. It can-
- not be modified by the application.
+ Color pair <STRONG>0</STRONG> is assumed to be white on black, but is actually
+ whatever the terminal implements before color is initialized. It
+ cannot be modified by the application.
</PRE><H3><a name="h3-has_colors">has_colors</a></H3><PRE>
The <STRONG>has_colors</STRONG> routine requires no arguments. It returns <STRONG>TRUE</STRONG> if the
- terminal can manipulate colors; otherwise, it returns <STRONG>FALSE</STRONG>. This rou-
- tine facilitates writing terminal-independent programs. For example, a
- programmer can use it to decide whether to use color or some other
- video attribute.
+ terminal can manipulate colors; otherwise, it returns <STRONG>FALSE</STRONG>. This
+ routine facilitates writing terminal-independent programs. For
+ example, a programmer can use it to decide whether to use color or some
+ other video attribute.
</PRE><H3><a name="h3-can_change_color">can_change_color</a></H3><PRE>
The <STRONG>can_change_color</STRONG> routine requires no arguments. It returns <STRONG>TRUE</STRONG> if
the terminal supports colors and can change their definitions; other,
- it returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-indepen-
- dent programs.
+ it returns <STRONG>FALSE</STRONG>. This routine facilitates writing terminal-
+ independent programs.
</PRE><H3><a name="h3-init_pair">init_pair</a></H3><PRE>
- The <STRONG>init_pair</STRONG> routine changes the definition of a color-pair. It takes
- three arguments: the number of the color-pair to be changed, the fore-
- ground color number, and the background color number. For portable ap-
- plications:
+ The <STRONG>init_pair</STRONG> routine changes the definition of a color pair. It takes
+ three arguments: the number of the color pair to be changed, the
+ foreground color number, and the background color number. For portable
+ applications:
- <STRONG>o</STRONG> The first argument must be a legal color pair value. If default
- colors are used (see <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>) the upper limit is ad-
- justed to allow for extra pairs which use a default color in fore-
- ground and/or background.
+ <STRONG>o</STRONG> The first argument must be a valid color pair value. If default
+ colors are used (see <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>) the upper limit is
+ adjusted to allow for extra pairs which use a default color in
+ foreground and/or background.
- <STRONG>o</STRONG> The second and third arguments must be legal color values.
+ <STRONG>o</STRONG> The second and third arguments must be valid color values.
- If the color-pair was previously initialized, the screen is refreshed
- and all occurrences of that color-pair are changed to the new defini-
- tion.
+ If the color pair was previously initialized, the screen is refreshed
+ and all occurrences of that color pair are changed to the new
+ definition.
- As an extension, ncurses allows you to set color pair <STRONG>0</STRONG> via the <STRONG>as-</STRONG>
- <STRONG><A HREF="assume_default_colors.3x.html">sume_default_colors(3x)</A></STRONG> routine, or to specify the use of default col-
-
ors (color number <STRONG>-1</STRONG>) if you first invoke the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>
+ As an extension, <EM>ncurses</EM> allows you to set color pair <STRONG>0</STRONG> via the
+ <STRONG><A HREF="default_colors.3x.html">assume_default_colors(3x)</A></STRONG> routine, or to specify the use of default
+
colors (color number <STRONG>-1</STRONG>) if you first invoke the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG>
routine.
</PRE><H3><a name="h3-init_extended_pair">init_extended_pair</a></H3><PRE>
Because <STRONG>init_pair</STRONG> uses signed <STRONG>short</STRONG>s for its parameters, that limits
- color-pairs and color-values to 32767 on modern hardware. The exten-
- sion <STRONG>init_extended_pair</STRONG> uses <STRONG>int</STRONG>s for the color-pair and color-value,
- allowing a larger number of colors to be supported.
+ color pairs and color-values to 32767 on modern hardware. The
+ extension <STRONG>init_extended_pair</STRONG> uses <STRONG>int</STRONG>s for the color pair and color-
+ value, allowing a larger number of colors to be supported.
</PRE><H3><a name="h3-init_color">init_color</a></H3><PRE>
four arguments: the number of the color to be changed followed by three
RGB values (for the amounts of red, green, and blue components).
- <STRONG>o</STRONG> The first argument must be a legal color value; default colors are
+ <STRONG>o</STRONG> The first argument must be a valid color value; default colors are
not allowed here. (See the section <STRONG>Colors</STRONG> for the default color
index.)
</PRE><H3><a name="h3-init_extended_color">init_extended_color</a></H3><PRE>
Because <STRONG>init_color</STRONG> uses signed <STRONG>short</STRONG>s for its parameters, that limits
- color-values and their red, green, and blue components to 32767 on mod-
- ern hardware. The extension <STRONG>init_extended_color</STRONG> uses <STRONG>int</STRONG>s for the col-
- or value and for setting the red, green, and blue components, allowing
- a larger number of colors to be supported.
+ color-values and their red, green, and blue components to 32767 on
+ modern hardware. The extension <STRONG>init_extended_color</STRONG> uses <STRONG>int</STRONG>s for the
+ color value and for setting the red, green, and blue components,
+ allowing a larger number of colors to be supported.
</PRE><H3><a name="h3-color_content">color_content</a></H3><PRE>
The <STRONG>color_content</STRONG> routine gives programmers a way to find the intensity
of the red, green, and blue (RGB) components in a color. It requires
four arguments: the color number, and three addresses of <STRONG>short</STRONG>s for
- storing the information about the amounts of red, green, and blue com-
- ponents in the given color.
+ storing the information about the amounts of red, green, and blue
+ components in the given color.
- <STRONG>o</STRONG> The first argument must be a legal color value, i.e., <STRONG>0</STRONG> through
+ <STRONG>o</STRONG> The first argument must be a valid color value, i.e., <STRONG>0</STRONG> through
<STRONG>COLORS-1</STRONG>, inclusive.
<STRONG>o</STRONG> The values that are stored at the addresses pointed to by the last
</PRE><H3><a name="h3-extended_color_content">extended_color_content</a></H3><PRE>
- Because <STRONG>color_content</STRONG> uses signed <STRONG>short</STRONG>s for its parameters, that lim-
- its color-values and their red, green, and blue components to 32767 on
- modern hardware. The extension <STRONG>extended_color_content</STRONG> uses <STRONG>int</STRONG>s for
+ Because <STRONG>color_content</STRONG> uses signed <STRONG>short</STRONG>s for its parameters, that
+ limits color-values and their red, green, and blue components to 32767
+ on modern hardware. The extension <STRONG>extended_color_content</STRONG> uses <STRONG>int</STRONG>s for
the color value and for returning the red, green, and blue components,
allowing a larger number of colors to be supported.
</PRE><H3><a name="h3-pair_content">pair_content</a></H3><PRE>
The <STRONG>pair_content</STRONG> routine allows programmers to find out what colors a
- given color-pair consists of. It requires three arguments: the color-
+ given color pair consists of. It requires three arguments: the color
pair number, and two addresses of <STRONG>short</STRONG>s for storing the foreground and
the background color numbers.
- <STRONG>o</STRONG> The first argument must be a legal color value, i.e., in the range
+ <STRONG>o</STRONG> The first argument must be a valid color value, i.e., in the range
<STRONG>1</STRONG> through <STRONG>COLOR_PAIRS-1</STRONG>, inclusive.
- <STRONG>o</STRONG> The values that are stored at the addresses pointed to by the sec-
- ond and third arguments are in the range <STRONG>0</STRONG> through <STRONG>COLORS</STRONG>, inclu-
- sive.
+ <STRONG>o</STRONG> The values that are stored at the addresses pointed to by the
+ second and third arguments are in the range <STRONG>0</STRONG> through <STRONG>COLORS</STRONG>,
+ inclusive.
</PRE><H3><a name="h3-extended_pair_content">extended_pair_content</a></H3><PRE>
Because <STRONG>pair_content</STRONG> uses signed <STRONG>short</STRONG>s for its parameters, that limits
- color-pair and color-values to 32767 on modern hardware. The extension
+ color pair and color-values to 32767 on modern hardware. The extension
<STRONG>extended_pair_content</STRONG> uses <STRONG>int</STRONG>s for the color pair and for returning
- the foreground and background colors, allowing a larger number of col-
- ors to be supported.
+ the foreground and background colors, allowing a larger number of
+ colors to be supported.
</PRE><H3><a name="h3-reset_color_pairs">reset_color_pairs</a></H3><PRE>
- The extension <STRONG>reset_color_pairs</STRONG> tells ncurses to discard all of the
- color-pair information which was set with <STRONG>init_pair</STRONG>. It also touches
+ The extension <STRONG>reset_color_pairs</STRONG> tells <EM>ncurses</EM> to discard all of the
+ color pair information which was set with <STRONG>init_pair</STRONG>. It also touches
the current- and standard-screens, allowing an application to switch
color palettes rapidly.
-</PRE><H3><a name="h3-PAIR_NUMBER">PAIR_NUMBER</a></H3><PRE>
- <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</EM>) extracts the color value from its <EM>attrs</EM> parameter
- and returns it as a color pair number.
+</PRE><H3><a name="h3-COLOR_PAIR">COLOR_PAIR</a></H3><PRE>
+ <STRONG>COLOR_PAIR(</STRONG><EM>n</EM><STRONG>)</STRONG> converts a color pair number to an attribute. Attributes
+ can hold color pairs in the range 0 to 255. If you need a color pair
+ larger than that, you must use functions such as <STRONG>attr_set</STRONG> (which pass
+ the color pair as a separate parameter) rather than the legacy
+ functions such as <STRONG>attrset</STRONG>.
-</PRE><H3><a name="h3-COLOR_PAIR">COLOR_PAIR</a></H3><PRE>
- Its inverse <STRONG>COLOR_PAIR(</STRONG><EM>n</EM><STRONG>)</STRONG> converts a color pair number to an attribute.
- Attributes can hold color pairs in the range 0 to 255. If you need a
- color pair larger than that, you must use functions such as <STRONG>attr_set</STRONG>
- (which pass the color pair as a separate parameter) rather than the
- legacy functions such as <STRONG>attrset</STRONG>.
+</PRE><H3><a name="h3-PAIR_NUMBER">PAIR_NUMBER</a></H3><PRE>
+ <STRONG>PAIR_NUMBER(</STRONG><EM>attr</EM>) extracts the color information from its <EM>attr</EM>
+ parameter and returns it as a color pair number; it is the inverse
+ operation of <STRONG>COLOR_PAIR</STRONG>.
</PRE><H2><a name="h2-RETURN-VALUE">RETURN VALUE</a></H2><PRE>
The routines <STRONG>can_change_color</STRONG> and <STRONG>has_colors</STRONG> return <STRONG>TRUE</STRONG> or <STRONG>FALSE</STRONG>.
- All other routines return the integer <STRONG>ERR</STRONG> upon failure and an <STRONG>OK</STRONG> (SVr4
- specifies only "an integer value other than <STRONG>ERR</STRONG>") upon successful com-
- pletion.
+ All other routines return the integer <STRONG>ERR</STRONG> upon failure and an <STRONG>OK</STRONG> (SVr4
+ specifies only "an integer value other than <STRONG>ERR</STRONG>") upon successful
+ completion.
- X/Open defines no error conditions. SVr4 does document some error con-
- ditions which apply in general:
+ X/Open defines no error conditions. SVr4 does document some error
+ conditions which apply in general:
<STRONG>o</STRONG> This implementation will return <STRONG>ERR</STRONG> on attempts to use color values
- outside the range <STRONG>0</STRONG> to <STRONG>COLORS</STRONG>-1 (except for the default colors ex-
- tension), or use color pairs outside the range <STRONG>0</STRONG> to <STRONG>COLOR_PAIRS-1</STRONG>.
+ outside the range <STRONG>0</STRONG> to <STRONG>COLORS</STRONG>-1 (except for the default colors
+ extension), or use color pairs outside the range <STRONG>0</STRONG> to
+ <STRONG>COLOR_PAIRS-1</STRONG>.
Color values used in <STRONG>init_color</STRONG> must be in the range <STRONG>0</STRONG> to <STRONG>1000</STRONG>.
An error is returned from secondary functions such as <STRONG>init_pair</STRONG> if
<STRONG>start_color</STRONG> was not called.
- <STRONG>o</STRONG> SVr4 does much the same, except that it returns <STRONG>ERR</STRONG> from <STRONG>pair_con-</STRONG>
- <STRONG>tent</STRONG> if the pair was not initialized using <STRONG>init_pairs</STRONG> and it re-
- turns <STRONG>ERR</STRONG> from <STRONG>color_content</STRONG> if the terminal does not support
+ <STRONG>o</STRONG> SVr4 does much the same, except that it returns <STRONG>ERR</STRONG> from
+ <STRONG>pair_content</STRONG> if the pair was not initialized using <STRONG>init_pairs</STRONG> and
+ it returns <STRONG>ERR</STRONG> from <STRONG>color_content</STRONG> if the terminal does not support
changing colors.
This implementation does not return <STRONG>ERR</STRONG> for either case.
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
- In the <STRONG>ncurses</STRONG> implementation, there is a separate color activation
- flag, color palette, color pairs table, and associated <STRONG>COLORS</STRONG> and <STRONG>COL-</STRONG>
- <STRONG>OR_PAIRS</STRONG> counts for each screen; the <STRONG>start_color</STRONG> function only affects
- the current screen. The SVr4/XSI interface is not really designed with
- this in mind, and historical implementations may use a single shared
- color palette.
+ In the <EM>ncurses</EM> implementation, there is a separate color activation
+ flag, color palette, color pairs table, and associated <STRONG>COLORS</STRONG> and
+ <STRONG>COLOR_PAIRS</STRONG> counts for each screen; the <STRONG>start_color</STRONG> function only
+ affects the current screen. The SVr4/XSI interface is not really
+ designed with this in mind, and historical implementations may use a
+ single shared color palette.
Setting an implicit background color via a color pair affects only
character cells that a character write operation explicitly touches.
<STRONG>o</STRONG> Color RGB values are not settable.
+</PRE><H2><a name="h2-EXTENSIONS">EXTENSIONS</a></H2><PRE>
+ The functions marked as extensions were designed for <STRONG><A HREF="ncurses.3x.html">ncurses(3x)</A></STRONG>, and
+ are not found in SVr4 <EM>curses</EM>, 4.4BSD <EM>curses</EM>, or any other previous
+ curses implementation.
+
+
</PRE><H2><a name="h2-PORTABILITY">PORTABILITY</a></H2><PRE>
- This implementation satisfies XSI Curses's minimum maximums for <STRONG>COLORS</STRONG>
- and <STRONG>COLOR_PAIRS</STRONG>.
+ Applications employing <EM>ncurses</EM> extensions should condition their use on
+ the visibility of the <STRONG>NCURSES_VERSION</STRONG> preprocessor macro.
+
+ This implementation satisfies X/Open Curses's minimum maximums for
+ <STRONG>COLORS</STRONG> and <STRONG>COLOR_PAIRS</STRONG>.
- The <STRONG>init_pair</STRONG> routine accepts negative values of foreground and back-
- ground color to support the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG> extension, but only
- if that routine has been first invoked.
+ The <STRONG>init_pair</STRONG> routine accepts negative values of foreground and
+ background color to support the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG> extension, but
+ only if that routine has been first invoked.
The assumption that <STRONG>COLOR_BLACK</STRONG> is the default background color for all
- terminals can be modified using the <STRONG><A HREF="default_colors.3x.html">assume_default_colors(3x)</A></STRONG> exten-
- sion.
+ terminals can be modified using the <STRONG><A HREF="default_colors.3x.html">assume_default_colors(3x)</A></STRONG>
+ extension.
- This implementation checks the pointers, e.g., for the values returned
- by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and will treat those as optional pa-
- rameters when null.
+ This implementation checks the pointers, e.g., for the values returned
+ by <STRONG>color_content</STRONG> and <STRONG>pair_content</STRONG>, and will treat those as optional
+ parameters when null.
- X/Open Curses does not specify a limit for the number of colors and
+ X/Open Curses does not specify a limit for the number of colors and
color pairs which a terminal can support. However, in its use of <STRONG>short</STRONG>
- for the parameters, it carries over SVr4's implementation detail for
+ for the parameters, it carries over SVr4's implementation detail for
the compiled terminfo database, which uses signed 16-bit numbers. This
- implementation provides extended versions of those functions which use
- <STRONG>short</STRONG> parameters, allowing applications to use larger color- and pair-
+ implementation provides extended versions of those functions which use
+ <STRONG>short</STRONG> parameters, allowing applications to use larger color- and pair-
numbers.
- The <STRONG>reset_color_pairs</STRONG> function is an extension of ncurses.
+ The <STRONG>reset_color_pairs</STRONG> function is an extension of <EM>ncurses</EM>.
+
+
+</PRE><H2><a name="h2-HISTORY">HISTORY</a></H2><PRE>
+ SVr3.2 introduced color support to curses in 1987.
+
+ SVr4 made internal changes, e.g., moving the storage for the color
+ state from <STRONG>SP</STRONG> (the <EM>SCREEN</EM> structure) to <STRONG>cur_term</STRONG> (the <EM>TERMINAL</EM>
+ structure), but provided the same set of library functions.
+
+ SVr4 curses limits the number of color pairs to 64, reserving color
+ pair zero (0) as the terminal's initial uncolored state. This limit
+ arises because the color pair information is a bitfield in the <STRONG>chtype</STRONG>
+ data type (denoted by <STRONG>A_COLOR</STRONG>).
+
+ Other implementations of curses had different limits:
+
+ <STRONG>o</STRONG> PCCurses (1987-1990) provided for only eight (8) colors.
+
+ <STRONG>o</STRONG> PDCurses (1992-present) inherited the 8-color limitation from
+ PCCurses, but changed this to 256 in version 2.5 (2001), along with
+ changing <STRONG>chtype</STRONG> from 16-bits to 32-bits.
+
+ <STRONG>o</STRONG> X/Open Curses (1992-present) added a new structure <STRONG>cchar_t</STRONG> to store
+ the character, attributes and color pair values, allowing increased
+ range of color pairs. Both color pairs and color-values used a
+ signed <STRONG>short</STRONG>, limiting values to 15 bits.
+
+ <STRONG>o</STRONG> <EM>ncurses</EM> (1992-present) uses eight bits for <STRONG>A_COLOR</STRONG> in <STRONG>chtype</STRONG>
+ values.
+
+ Version 5.3 provided a wide-character interface (2002), but left
+ color pairs as part of the attributes-field.
+
+ Since version 6 (2015), ncurses uses a separate <STRONG>int</STRONG> for color pairs
+ in the <STRONG>cchar_t</STRONG> values. When those color pair values fit in 8 bits,
+ ncurses allows color pairs to be manipulated via the functions
+ using <STRONG>chtype</STRONG> values.
+
+ <STRONG>o</STRONG> NetBSD curses used 6 bits from 2000 (when colors were first
+ supported) until 2004. At that point, NetBSD changed to use 10
+ bits. As of 2021, that size is unchanged. Like <EM>ncurses</EM> before
+ version 6, the NetBSD color pair information is stored in the
+ attributes field of <STRONG>cchar_t</STRONG>, limiting the number of color pairs by
+ the size of the bitfield.
</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_initscr.3x.html">curs_initscr(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>, <STRONG>de-</STRONG>
- <STRONG><A HREF="default_colors.3x.html">fault_colors(3x)</A></STRONG>
+ <STRONG><A HREF="ncurses.3x.html">curses(3x)</A></STRONG>, <STRONG><A HREF="curs_attr.3x.html">curs_attr(3x)</A></STRONG>, <STRONG><A HREF="curs_initscr.3x.html">curs_initscr(3x)</A></STRONG>, <STRONG><A HREF="curs_variables.3x.html">curs_variables(3x)</A></STRONG>,
+ <STRONG><A HREF="default_colors.3x.html">default_colors(3x)</A></STRONG>
-
<STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
+
ncurses 6.4 2024-04-20 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
</PRE>
<div class="nav">
<ul>
<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-Rendering">Rendering</a></li>
</ul>
</li>
<li><a href="#h2-CONSTANTS">CONSTANTS</a></li>
<li><a href="#h3-pair_content">pair_content</a></li>
<li><a href="#h3-extended_pair_content">extended_pair_content</a></li>
<li><a href="#h3-reset_color_pairs">reset_color_pairs</a></li>
-<li><a href="#h3-PAIR_NUMBER">PAIR_NUMBER</a></li>
<li><a href="#h3-COLOR_PAIR">COLOR_PAIR</a></li>
+<li><a href="#h3-PAIR_NUMBER">PAIR_NUMBER</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-EXTENSIONS">EXTENSIONS</a></li>
<li><a href="#h2-PORTABILITY">PORTABILITY</a></li>
+<li><a href="#h2-HISTORY">HISTORY</a></li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
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