139 lines
6.4 KiB
Groff
139 lines
6.4 KiB
Groff
.TH curs_color 3X ""
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.SH NAME
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\fBcurs_color\fR: \fBstart_color\fR, \fBinit_pair\fR,
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\fBinit_color\fR, \fBhas_colors\fR, \fBcan_change_color\fR,
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\fBcolor_content\fR, \fBpair_content\fR - \fBncurses\fR color
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manipulation routines
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.SH SYNOPSIS
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\fB# include <ncurses.h>\fR
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.br
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\fBint start_color(void);\fR
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.br
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\fBint init_pair(short pair, short f, short b);\fR
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.br
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\fBint init_color(short color, short r, short g, short b);\fR
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.br
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\fBbool has_colors(void);\fR
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.br
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\fBbool can_change_color(void);\fR
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.br
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\fBint color_content(short color, short *r, short *g, short *b);\fR
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.br
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\fBint pair_content(short pair, short *f, short *b);\fR
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.br
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.SH DESCRIPTION
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.SS Overview
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\fBncurses\fR support color attributes on terminals with that capability. To
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use these routines \fBstart_color\fR must be called, usually right after
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\fBinitscr\fR. Colors are always used in pairs (referred to as color-pairs).
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A color-pair consists of a foreground color (for characters) and a background
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color (for the blank field on which the characters are displayed). A
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programmer initializes a color-pair with the routine \fBinit_pair\fR. After it
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has been initialized, \fBCOLOR_PAIR\fR(\fIn\fR), a macro defined in
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\fB<ncurses.h>\fR, can be used as a new video attribute.
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If a terminal is capable of redefining colors, the programmer can use the
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routine \fBinit_color\fR to change the definition of a color. The routines
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\fBhas_colors\fR and \fBcan_change_color\fR return \fBTRUE\fR or \fBFALSE\fR,
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depending on whether the terminal has color capabilities and whether the
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programmer can change the colors. The routine \fBcolor_content\fR allows a
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programmer to extract the amounts of red, green, and blue components in an
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initialized color. The routine \fBpair_content\fR allows a programmer to find
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out how a given color-pair is currently defined.
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.SS Routine Descriptions
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The \fBstart_color\fR routine requires no arguments. It must be
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called if the programmer wants to use colors, and before any other
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color manipulation routine is called. It is good practice to call
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this routine right after \fBinitscr\fR. \fBstart_color\fR initializes
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eight basic colors (black, red, green, yellow, blue, magenta, cyan,
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and white), and two global variables, \fBCOLORS\fR and
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\fBCOLOR_PAIRS\fR (respectively defining the maximum number of colors
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and color-pairs the terminal can support). It also restores the
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colors on the terminal to the values they had when the terminal was
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just turned on.
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The \fBinit_pair\fR routine changes the definition of a color-pair. It takes
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three arguments: the number of the color-pair to be changed, the foreground
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color number, and the background color number. The value of the first argument
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must be between \fB1\fR and \fBCOLOR_PAIRS-1\fR. The value of the second and
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third arguments must be between 0 and \fBCOLORS\fR (the 0 color pair is wired
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to white on black and cannot be changed). If the color-pair was previously
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initialized, the screen is refreshed and all occurrences of that color-pair is
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changed to the new definition.
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The \fBinit_color\fR routine changes the definition of a color. It takes four
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arguments: the number of the color to be changed followed by three RGB values
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(for the amounts of red, green, and blue components). The value of the first
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argument must be between \fB0\fR and \fBCOLORS\fR. (See the section
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\fBColors\fR for the default color index.) Each of the last three arguments
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must be a value between 0 and 1000. When \fBinit_color\fR is used, all
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occurrences of that color on the screen immediately change to the new
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definition.
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The \fBhas_colors\fR routine requires no arguments. It returns \fBTRUE\fR if
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the terminal can manipulate colors; otherwise, it returns \fBFALSE\fR. This
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routine facilitates writing terminal-independent programs. For example, a
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programmer can use it to decide whether to use color or some other video
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attribute.
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The \fBcan_change_color\fR routine requires no arguments. It returns
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\fBTRUE\fR if the terminal supports colors and can change their definitions;
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other, it returns \fBFALSE\fR. This routine facilitates writing
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terminal-independent programs.
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The \fBcolor_content\fR routine gives programmers a way to find the intensity
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of the red, green, and blue (RGB) components in a color. It requires four
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arguments: the color number, and three addresses of \fBshort\fRs for storing
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the information about the amounts of red, green, and blue components in the
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given color. The value of the first argument must be between 0 and
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\fBCOLORS\fR. The values that are stored at the addresses pointed to by the
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last three arguments are between 0 (no component) and 1000 (maximum amount of
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component).
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The \fBpair_content\fR routine allows programmers to find out what colors a
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given color-pair consists of. It requires three arguments: the color-pair
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number, and two addresses of \fBshort\fRs for storing the foreground and the
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background color numbers. The value of the first argument must be between 1
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and \fBCOLOR_PAIRS-1\fR. The values that are stored at the addresses pointed
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to by the second and third arguments are between 0 and \fBCOLORS\fR.
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.SS Colors
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In \fB<ncurses.h>\fR the following macros are defined. These are the default
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colors. \fBncurses\fR also assumes that \fBCOLOR_BLACK\fR is the default
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background color for all terminals.
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.nf
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\fBCOLOR_BLACK\fR
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\fBCOLOR_RED\fR
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\fBCOLOR_GREEN\fR
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\fBCOLOR_YELLOW\fR
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\fBCOLOR_BLUE\fR
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\fBCOLOR_MAGENTA\fR
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\fBCOLOR_CYAN\fR
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\fBCOLOR_WHITE\fR
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.fi
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.SH RETURN VALUE
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All routines that return an integer return \fBERR\fR upon failure and \fBOK\fR
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upon successful completion.
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.SH BUGS
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Several caveats apply onn 386 and 486 machines with VGA-compatible graphics:
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COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW combined with
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the \fBA_BOLD\fR attribute.
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The A_BLINK attribute should in theory cause the background to go bright. This
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often fails to work, and even some cards for which it mostly works (such as the
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Paradise and compatibles) do the wrong thing when you try to set a bright
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"yellow" background (you get a blinking yellow foreground instead).
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Color RGB values are not settable.
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.SH CAPABILITIES
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\fBsetf\fR, \fBsetb\fR, \fBsetaf\fR, \fBsetab\fR. The ncurses library uses
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the second pair by preference, falling back to the first.
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.SH SEE ALSO
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\fBncurses\fR(3X), \fBcurs_initscr\fR(3X), \fBcurs_attr\fR(3X)
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.\"#
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.\"# The following sets edit modes for GNU EMACS
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.\"# Local Variables:
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.\"# mode:nroff
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.\"# fill-column:79
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