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Diffstat (limited to 'man/man3/color.3')
| -rw-r--r-- | man/man3/color.3 | 56 |
1 files changed, 56 insertions, 0 deletions
diff --git a/man/man3/color.3 b/man/man3/color.3 new file mode 100644 index 00000000..91d34a62 --- /dev/null +++ b/man/man3/color.3 @@ -0,0 +1,56 @@ +.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 +.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) |