curses support color attributes on terminals with that ca-
pability. To use these routines start_color must be
called, usually right after initscr. Colors are always
@@ -91,7 +94,9 @@
The routine pair_content allows a programmer to find out
how a given color-pair is currently defined.
- RoutineDescriptions
+
+
The start_color 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
@@ -104,28 +109,54 @@
terminal to the values they had when the terminal was just
turned on.
- The init_pair 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
+ These limits apply to color values and color pairs. Val-
+ ues outside these limits are not legal, and may result in
+ a runtime error:
+
+ oCOLORS corresponds to the terminal database's max_col-
+ ors capability, which is typically a signed 16-bit in-
+ teger (see terminfo(5)).
+
+ o color values are expected to be in the range 0 to COL-
+ ORS-1, inclusive (including 0 and COLORS-1).
+
+ o a special color value -1 is used in certain extended
+ functions to denote the defaultcolor (see use_de-
+ fault_colors).
+
+ oCOLOR_PAIRS corresponds to the terminal database's
+ max_pairs capability, which is typically a signed
+ 16-bit integer (see terminfo(5)).
+
+ o legal color pair values are in the range 1 to COL-
+ OR_PAIRS-1, inclusive.
+
+ o color pair 0 is special; it denotes "no color".
+
+ Color pair 0 is assumed to be white on black, but is
+ actually whatever the terminal implements before color
+ is initialized. It cannot be modified by the applica-
+ tion.
+
+ The init_pair 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:
- o The value of the first argument must be between 1 and
- COLOR_PAIRS-1, except that if default colors are used
- (see use_default_colors) the upper limit is adjusted
- to allow for extra pairs which use a default color in
- foreground and/or background.
+ o The first argument must be a legal color pair value.
+ If default colors are used (see use_default_colors)
+ the upper limit is adjusted to allow for extra pairs
+ which use a default color in foreground and/or back-
+ ground.
- o The value of the second and third arguments must be
- between 0 and COLORS. Color pair 0 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.
+ o The second and third arguments must be legal 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 definition.
- As an extension, ncurses allows you to set color pair 0
+ As an extension, ncurses allows you to set color pair 0
via the assume_default_colors routine, or to specify the
use of default colors (color number -1) if you first in-
voke the use_default_colors routine.
@@ -133,46 +164,50 @@
The init_color routine changes the definition of a color.
It takes four arguments: the number of the color to be
changed followed by three RGB values (for the amounts of
- red, green, and blue components). The value of the first
- argument must be between 0 and COLORS. (See the section
- Colors for the default color index.) Each of the last
- three arguments must be a value between 0 and 1000. When
- init_color is used, all occurrences of that color on the
- screen immediately change to the new definition.
-
- The has_colors routine requires no arguments. It returns
- TRUE if the terminal can manipulate colors; otherwise, it
+ red, green, and blue components). The first argument must
+ be a legal color value; default colors are not allowed
+ here. (See the section Colors for the default color in-
+ dex.) Each of the last three arguments must be a value in
+ the range 0 through 1000. When init_color is used, all
+ occurrences of that color on the screen immediately change
+ to the new definition.
+
+ The has_colors routine requires no arguments. It returns
+ TRUE if the terminal can manipulate colors; otherwise, it
returns FALSE. This routine facilitates writing terminal-
- independent programs. For example, a programmer can use
- it to decide whether to use color or some other video at-
+ independent programs. For example, a programmer can use
+ it to decide whether to use color or some other video at-
tribute.
- The can_change_color routine requires no arguments. It
- returns TRUE if the terminal supports colors and can
- change their definitions; other, it returns FALSE. This
+ The can_change_color routine requires no arguments. It
+ returns TRUE if the terminal supports colors and can
+ change their definitions; other, it returns FALSE. This
routine facilitates writing terminal-independent programs.
- The color_content routine gives programmers a way to find
+ The color_content 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 shorts for storing the information
- about the amounts of red, green, and blue components in
- the given color. The value of the first argument must be
- between 0 and COLORS. The values that are stored at the
- addresses pointed to by the last three arguments are be-
- tween 0 (no component) and 1000 (maximum amount of compo-
- nent).
-
- The pair_content routine allows programmers to find out
- what colors a given color-pair consists of. It requires
- three arguments: the color-pair number, and two addresses
- of shorts for storing the foreground and the background
- color numbers. The value of the first argument must be
- between 1 and COLOR_PAIRS-1. The values that are stored
- at the addresses pointed to by the second and third argu-
- ments are between 0 and COLORS.
-
- Colors
+ and three addresses of shorts for storing the information
+ about the amounts of red, green, and blue components in
+ the given color. The first argument must be a legal color
+ value, i.e., 0 through COLORS-1, inclusive. The values
+ that are stored at the addresses pointed to by the last
+ three arguments are in the range 0 (no component) through
+ 1000 (maximum amount of component), inclusive.
+
+ The pair_content routine allows programmers to find out
+ what colors a given color-pair consists of. It requires
+ three arguments: the color-pair number, and two addresses
+ of shorts for storing the foreground and the background
+ color numbers. The first argument must be a legal color
+ value, i.e., in the range 1 through COLOR_PAIRS-1, inclu-
+ sive. The values that are stored at the addresses pointed
+ to by the second and third arguments are in the range 0
+ through COLORS, inclusive.
+
+
+
In <curses.h> the following macros are defined. These are
the default colors. curses also assumes that COLOR_BLACK
is the default background color for all terminals.
@@ -188,7 +223,7 @@
The routines can_change_color() and has_colors() return
TRUE or FALSE.
@@ -198,12 +233,12 @@
X/Open defines no error conditions. This implementation
will return ERR on attempts to use color values outside
- the range 0 to COLORS-1 (except for the default colors ex-
- tension), or use color pairs outside the range 0 to COL-
- OR_PAIR-1. Color values used in init_color must be in the
- range 0 to 1000. An error is returned from all functions
- if the terminal has not been initialized. An error is re-
- turned from secondary functions such as init_pair if
+ the range 0 to COLORS-1 (except for the default colors ex-
+ tension), or use color pairs outside the range 0 to COL-
+ OR_PAIRS-1. Color values used in init_color must be in
+ the range 0 to 1000. An error is returned from all func-
+ tions if the terminal has not been initialized. An error
+ is returned from secondary functions such as init_pair if
start_color was not called.
init_color
@@ -217,7 +252,7 @@
In the ncurses implementation, there is a separate color
activation flag, color palette, color pairs table, and as-
sociated COLORS and COLOR_PAIRS counts for each screen;
@@ -249,7 +284,7 @@