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-<H1 class="no-header">curs_color 3x 2023-10-21 ncurses 6.4 Library calls</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> Library calls <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
<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> - manipulate terminal colors with <EM>curses</EM>
+ <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>void</STRONG> <STRONG>reset_color_pairs(void);</STRONG>
<STRONG>int</STRONG> <STRONG>COLOR_PAIR(int</STRONG> <EM>n</EM><STRONG>);</STRONG>
- <STRONG>PAIR_NUMBER(</STRONG><EM>attrs</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>
- <EM>curses</EM> 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
- displayed). 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.
-
- 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
- routines <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 programmer can change the colors. The routine <STRONG>color_content</STRONG> allows
- a programmer 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.
+ <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 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 <EM>curses</EM> library combines these inputs to produce the actual
- foreground 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
- containing video attributes including a color pair value. Some
- functions such as <STRONG>wattr_set</STRONG> use a separate parameter which is the color
- pair number.
+ 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 <EM>curses</EM> 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
<STRONG>o</STRONG> <EM>curses</EM> next checks the window attribute.
- <STRONG>o</STRONG> If the window attribute does not use color pair 0, <EM>curses</EM> 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, <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, <EM>curses</EM> prefers the color pair from the
- parameter, if it is nonzero. Otherwise, it tries the window
+ <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 <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
+ 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.
<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
+ 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>
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>
- (respectively defining the maximum number of colors and color-pairs
+ (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
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>
capability, (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>,
+ <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".
</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
+ 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
+ <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
+ 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
+ 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
- extension <STRONG>init_extended_pair</STRONG> uses <STRONG>int</STRONG>s for the color-pair and color-
+ 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.
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.)
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-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
</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
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
+ 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
+ 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
- extension), or use color pairs outside the range <STRONG>0</STRONG> to
+ 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 all functions if the terminal has not
+ An error is returned from all functions if the terminal has not
been initialized.
- An error is returned from secondary functions such as <STRONG>init_pair</STRONG> if
+ 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_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
+ <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.
<STRONG>init_color</STRONG>
returns an error if the terminal does not support this feature,
- e.g., if the <STRONG>initialize_color</STRONG> capability is absent from the
+ e.g., if the <STRONG>initialize_color</STRONG> capability is absent from the
terminal description.
<STRONG>start_color</STRONG>
</PRE><H2><a name="h2-NOTES">NOTES</a></H2><PRE>
- 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
+ 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.
- To change the background color used when parts of a window are blanked
+ Setting an implicit background color via a color pair affects only
+ character cells that a character write operation explicitly touches.
+ To change the background color used when parts of a window are blanked
by erasing or scrolling operations, see <STRONG><A HREF="curs_bkgd.3x.html">curs_bkgd(3x)</A></STRONG>.
- Several caveats apply on older x86 machines (e.g., i386, i486) with
+ Several caveats apply on older x86 machines (e.g., i386, i486) with
VGA-compatible graphics:
- <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW
+ <STRONG>o</STRONG> COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW
combined with the <STRONG>A_BOLD</STRONG> attribute.
- <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the background to go
+ <STRONG>o</STRONG> The A_BLINK attribute should in theory cause the background to go
bright. This often fails to work, and even some cards for which it
- mostly works (such as the Paradise and compatibles) do the wrong
- thing when you try to set a bright "yellow" background (you get a
+ mostly works (such as the Paradise and compatibles) do the wrong
+ thing when you try to set a bright "yellow" background (you get a
blinking yellow foreground instead).
<STRONG>o</STRONG> Color RGB values are not settable.
-</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 <STRONG>SCREEN</STRONG> structure) to <STRONG>cur_term</STRONG> (the <STRONG>TERMINAL</STRONG>
- 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> ncurses (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 ncurses 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-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>
+ Applications employing <EM>ncurses</EM> extensions should condition their use on
+ the visibility of the <STRONG>NCURSES_VERSION</STRONG> preprocessor macro.
-</PRE><H3><a name="h3-Extensions">Extensions</a></H3><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 curses, 4.4BSD curses, or any other previous
- version of curses.
-
-
-</PRE><H3><a name="h3-Standards">Standards</a></H3><PRE>
- This implementation satisfies XSI Curses's minimum maximums for <STRONG>COLORS</STRONG>
- and <STRONG>COLOR_PAIRS</STRONG>.
+ 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
background color to support the <STRONG><A HREF="default_colors.3x.html">use_default_colors(3x)</A></STRONG> extension, but
<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><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>
-ncurses 6.4 202
3-10-21 <STRONG><A HREF="curs_color.3x.html">curs_color(3x)</A></STRONG>
+ncurses 6.4 202
4-04-20 <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-PORTABILITY">PORTABILITY</a>
-<ul>
-<li><a href="#h3-Extensions">Extensions</a></li>
-<li><a href="#h3-Standards">Standards</a></li>
-</ul>
-</li>
<li><a href="#h2-SEE-ALSO">SEE ALSO</a></li>
</ul>
</div>
projects / ncurses.git / blobdiff