.\" $OpenBSD: curs_color.3,v 1.10 2010/01/12 23:21:59 nicm Exp $ .\" .\"*************************************************************************** .\" Copyright (c) 1998-2004,2005 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 * .\" "Software"), to deal in the Software without restriction, including * .\" without limitation the rights to use, copy, modify, merge, publish, * .\" distribute, distribute with modifications, sublicense, and/or sell * .\" copies of the Software, and to permit persons to whom the Software is * .\" furnished to do so, subject to the following conditions: * .\" * .\" The above copyright notice and this permission notice shall be included * .\" in all copies or substantial portions of the Software. * .\" * .\" THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS * .\" OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF * .\" MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. * .\" IN NO EVENT SHALL THE ABOVE COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, * .\" DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR * .\" OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR * .\" THE USE OR OTHER DEALINGS IN THE SOFTWARE. * .\" * .\" Except as contained in this notice, the name(s) of the above copyright * .\" holders shall not be used in advertising or otherwise to promote the * .\" sale, use or other dealings in this Software without prior written * .\" authorization. * .\"*************************************************************************** .\" .\" $Id: curs_color.3,v 1.10 2010/01/12 23:21:59 nicm Exp $ .TH curs_color 3 "" .na .hy 0 .SH NAME \fBstart_color\fR, \fBinit_pair\fR, \fBinit_color\fR, \fBhas_colors\fR, \fBcan_change_color\fR, \fBcolor_content\fR, \fBpair_content\fR, \fBCOLOR_PAIR\fR - \fBcurses\fR color manipulation routines .ad .hy .SH SYNOPSIS \fB# include \fR .br \fBint start_color(void);\fR .br \fBint init_pair(short pair, short f, short b);\fR .br \fBint init_color(short color, short r, short g, short b);\fR .br \fBbool has_colors(void);\fR .br \fBbool can_change_color(void);\fR .br \fBint color_content(short color, short *r, short *g, short *b);\fR .br \fBint pair_content(short pair, short *f, short *b);\fR .br .SH DESCRIPTION .SS Overview \fBcurses\fR support color attributes on terminals with that capability. To use these routines \fBstart_color\fR must be called, usually right after \fBinitscr\fR. 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 \fBinit_pair\fR. After it has been initialized, \fBCOLOR_PAIR\fR(\fIn\fR), a macro defined in \fB\fR, can be used as a new video attribute. .PP If a terminal is capable of redefining colors, the programmer can use the routine \fBinit_color\fR to change the definition of a color. The routines \fBhas_colors\fR and \fBcan_change_color\fR return \fBTRUE\fR or \fBFALSE\fR, depending on whether the terminal has color capabilities and whether the programmer can change the colors. The routine \fBcolor_content\fR allows a programmer to extract the amounts of red, green, and blue components in an initialized color. The routine \fBpair_content\fR allows a programmer to find out how a given color-pair is currently defined. .SS Routine Descriptions The \fBstart_color\fR 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 \fBinitscr\fR. \fBstart_color\fR initializes eight basic colors (black, red, green, yellow, blue, magenta, cyan, and white), and two global variables, \fBCOLORS\fR and \fBCOLOR_PAIRS\fR (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. .PP The \fBinit_pair\fR 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: .TP 5 - The value of the first argument must be between \fB1\fR and \fBCOLOR_PAIRS-1\fR. .TP 5 - The value of the second and third arguments must be between 0 and \fBCOLORS\fR. 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. .PP If the color-pair was previously initialized, the screen is refreshed and all occurrences of that color-pair are changed to the new definition. .PP As an extension, ncurses allows you to set color pair 0 via the \fBassume_default_colors\fR routine, or to specify the use of default colors (color number \fB-1\fR) if you first invoke the \fBuse_default_colors\fR routine. .PP The \fBinit_color\fR 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 \fB0\fR and \fBCOLORS\fR. (See the section \fBColors\fR for the default color index.) Each of the last three arguments must be a value between 0 and 1000. When \fBinit_color\fR is used, all occurrences of that color on the screen immediately change to the new definition. .PP The \fBhas_colors\fR routine requires no arguments. It returns \fBTRUE\fR if the terminal can manipulate colors; otherwise, it returns \fBFALSE\fR. 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. .PP The \fBcan_change_color\fR routine requires no arguments. It returns \fBTRUE\fR if the terminal supports colors and can change their definitions; other, it returns \fBFALSE\fR. This routine facilitates writing terminal-independent programs. .PP The \fBcolor_content\fR 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 \fBshort\fRs 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 \fBCOLORS\fR. The values that are stored at the addresses pointed to by the last three arguments are between 0 (no component) and 1000 (maximum amount of component). .PP The \fBpair_content\fR 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 \fBshort\fRs for storing the foreground and the background color numbers. The value of the first argument must be between 1 and \fBCOLOR_PAIRS-1\fR. The values that are stored at the addresses pointed to by the second and third arguments are between 0 and \fBCOLORS\fR. .SS Colors In \fB\fR the following macros are defined. These are the default colors. \fBcurses\fR also assumes that \fBCOLOR_BLACK\fR is the default background color for all terminals. .PP .nf \fBCOLOR_BLACK\fR \fBCOLOR_RED\fR \fBCOLOR_GREEN\fR \fBCOLOR_YELLOW\fR \fBCOLOR_BLUE\fR \fBCOLOR_MAGENTA\fR \fBCOLOR_CYAN\fR \fBCOLOR_WHITE\fR .fi .SH RETURN VALUE The routines \fBcan_change_color()\fR and \fBhas_colors()\fR return \fBTRUE\fR or \fBFALSE\fR. .PP All other routines return the integer \fBERR\fR upon failure and an \fBOK\fR (SVr4 specifies only "an integer value other than \fBERR\fR") upon successful completion. .PP X/Open defines no error conditions. This implementation will return \fBERR\fR on attempts to use color values outside the range 0 to COLORS-1 (except for the default colors extension), or use color pairs outside the range 0 to COLOR_PAIR-1. Color values used in \fBinit_color\fP 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 returned from secondary functions such as \fBinit_pair\fP if \fBstart_color\fP was not called. .RS .TP 5 \fBinit_color\fP returns an error if the terminal does not support this feature, e.g., if the \fIinitialize_color\fP capability is absent from the terminal description. .TP 5 \fBstart_color\fP returns an error If the color table cannot be allocated. .RE .SH NOTES In the \fIncurses\fR implementation, there is a separate color activation flag, color palette, color pairs table, and associated COLORS and COLOR_PAIRS counts for each screen; the \fBstart_color\fR 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. .PP Note that 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 \fBcurs_bkgd\fR(3). .PP Several caveats apply on 386 and 486 machines with VGA-compatible graphics: .TP 5 - COLOR_YELLOW is actually brown. To get yellow, use COLOR_YELLOW combined with the \fBA_BOLD\fR attribute. .TP 5 - 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 blinking yellow foreground instead). .TP 5 - Color RGB values are not settable. .SH PORTABILITY This implementation satisfies XSI Curses's minimum maximums for \fBCOLORS\fR and \fBCOLOR_PAIRS\fR. .PP The \fBinit_pair\fP routine accepts negative values of foreground and background color to support the \fBuse_default_colors\fP extension, but only if that routine has been first invoked. .PP The assumption that \fBCOLOR_BLACK\fR is the default background color for all terminals can be modified using the \fBassume_default_colors\fP extension. .PP This implementation checks the pointers, e.g., for the values returned by \fBcolor_content\fP and \fBpair_content\fP, and will treat those as optional parameters when null. .SH SEE ALSO \fBcurses\fR(3), \fBcurs_initscr\fR(3), \fBcurs_attr\fR(3), \fBdefault_colors\fR(3) .\"# .\"# The following sets edit modes for GNU EMACS .\"# Local Variables: .\"# mode:nroff .\"# fill-column:79 .\"# End: