The cpdf_setrgbcolor() function sets the current drawing and filling color to the given rgb color value. Returns TRUE on success or FALSE on failure.
Note: The values are expected to be floating point values between 0.0 and 1.0. (i.e black is (0.0, 0.0, 0.0) and white is (1.0, 1.0, 1.0)).
See also cpdf_setrgbcolor_stroke() and cpdf_setrgbcolor_fill().