From fd5651a159da880b0c378ae9d2a2b4ac1c0614b3 Mon Sep 17 00:00:00 2001 From: Tavian Barnes Date: Tue, 11 Mar 2014 20:20:07 -0400 Subject: Refactor hue comparator into color.c. --- color.c | 22 ++++++++++++++++++++++ 1 file changed, 22 insertions(+) (limited to 'color.c') diff --git a/color.c b/color.c index 34eab01..d75d58f 100644 --- a/color.c +++ b/color.c @@ -11,6 +11,7 @@ #include "color.h" #include +#define PI 3.1415926535897932 void color_unpack(uint8_t pixel[3], uint32_t color) @@ -117,3 +118,24 @@ color_set_Luv(double coords[3], uint32_t color) coords[1] = 13.0*coords[0]*(uprime - unprime); coords[2] = 13.0*coords[0]*(vprime - vnprime); } + +static double +hue(uint32_t color) +{ + double RGB[3]; + color_set_RGB(RGB, color); + + double hue = atan2(sqrt(3.0)*(RGB[1] - RGB[2]), 2*RGB[0] - RGB[1] - RGB[2]); + if (hue < 0.0) { + hue += 2.0*PI; + } + return hue; +} + +int +color_comparator(const void *a, const void *b) +{ + double ahue = hue(*(uint32_t *)a); + double bhue = hue(*(uint32_t *)b); + return (ahue > bhue) - (ahue < bhue); +} -- cgit v1.2.3