mirror of
https://github.com/9fans/plan9port.git
synced 2025-01-12 11:10:07 +00:00
977b25a76a
The overloading of IR emits magic \X'...' sequences that turn into HTML manual links. But not all such IR invocations should be manual links; those had to be written to avoid the IR macro before. Worse, the \X'...' ending the IR causes troff to emit only a single space after a period. Defining a new IM macro for manual references fixes both problems. Fixes #441.
56 lines
1.3 KiB
Groff
56 lines
1.3 KiB
Groff
.TH COLOR 3
|
|
.SH NAME
|
|
cmap2rgb, cmap2rgba, rgb2cmap \- colors and color maps
|
|
.SH SYNOPSIS
|
|
.B #include <u.h>
|
|
.br
|
|
.B #include <libc.h>
|
|
.br
|
|
.B #include <draw.h>
|
|
.PP
|
|
.B
|
|
int rgb2cmap(int red, int green, int blue)
|
|
.PP
|
|
.B
|
|
int cmap2rgb(int col)
|
|
.PP
|
|
.B
|
|
int cmap2rgba(int col)
|
|
.SH DESCRIPTION
|
|
These routines convert between `true color' red/green/blue triples and the Plan 9 color map.
|
|
See
|
|
.IM color (7)
|
|
for a description of RGBV, the standard color map.
|
|
.PP
|
|
.I Rgb2cmap
|
|
takes a trio of color values, scaled from 0 (no intensity) to 255 (full intensity),
|
|
and returns the index of the color in RGBV closest to that represented
|
|
by those values.
|
|
.PP
|
|
.I Cmap2rgb
|
|
decomposes the color of RGBV index
|
|
.I col
|
|
and returns a 24-bit integer with the low 8 bits representing the blue value,
|
|
the next 8 representing green, and the next 8 representing red.
|
|
.I Cmap2rgba
|
|
decomposes the color of RGBV index
|
|
.I col
|
|
and returns a 32-bit integer with the low 8 bits representing an alpha value,
|
|
defined to be 255,
|
|
and the next 8 representing blue, then green, then red, as for
|
|
.I cmap2rgba
|
|
shifted up 8 bits.
|
|
This 32-bit representation is the format used by
|
|
.IM draw (3)
|
|
and
|
|
.IM memdraw (3)
|
|
library routines that
|
|
take colors as arguments.
|
|
.SH SOURCE
|
|
.B \*9/src/libdraw
|
|
.SH SEE ALSO
|
|
.IM graphics (3) ,
|
|
.IM allocimage (3) ,
|
|
.IM draw (3) ,
|
|
.IM image (7) ,
|
|
.IM color (7)
|