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NAME
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cmap2rgb, cmap2rgba, rgb2cmap – colors and color maps
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <draw.h>
int rgb2cmap(int red, int green, int blue)
int cmap2rgb(int col)
int cmap2rgba(int col)
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DESCRIPTION
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These routines convert between ‘true color’ red/green/blue triples
and the Plan 9 color map. See color(7) for a description of RGBV,
the standard color map.
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.
Cmap2rgb decomposes the color of RGBV index 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.
Cmap2rgba decomposes the color of RGBV index 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 cmap2rgba shifted
up 8 bits. This 32-bit representation is the format used by draw(3)
and memdraw(3) library routines that take colors as arguments.
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SOURCE
SEE ALSO
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