| .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 (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 |
| .IR draw (3) |
| and |
| .IR memdraw (3) |
| library routines that |
| take colors as arguments. |
| .SH SOURCE |
| .B \*9/src/libdraw |
| .SH SEE ALSO |
| .IR graphics (3), |
| .IR allocimage (3), |
| .IR draw (3), |
| .IR image (7), |
| .IR color (7) |