The cpdf_setrgbcolor_stroke() function sets the current drawing color to the given rgb color value. 成功回傳TRUE失敗回傳FALSE。
備注: 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_fill() and cpdf_setrgbcolor().