NAME
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cmap2rgb, cmap2rgba, rgb2cmap – colors and color maps |
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) |
DESCRIPTION
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These routines convert between `true color' red/green/blue triples
and the Plan 9 color map. See color(6) 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(2) and memdraw(2) library
routines that take colors as arguments. |
SOURCE
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/sys/src/libdraw |
SEE ALSO
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graphics(2), allocimage(2), draw(2), image(6), color(6) |