ref: a24a294465b5e4c4d68618c4bec13e900dbd4ff7
dir: /sys/man/2/color/
.TH COLOR 2 .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 .IR color (6) 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 .IR draw (2) and .IR memdraw (2) library routines that take colors as arguments. .SH SOURCE .B /sys/src/libdraw .SH SEE ALSO .IR graphics (2), .IR allocimage (2), .IR draw (2), .IR image (6), .IR color (6)