From 5858cac873dac28087b3d31cac254c31a7b04e38 Mon Sep 17 00:00:00 2001 From: Damien Lespiau Date: Mon, 13 May 2013 13:24:21 +0100 Subject: [PATCH] color: Add HSL conversion functions This allows to easily caculate shades of the same color or pick colors with the same saturation/luminance. In short, all sorts of interesting things. Reviewed-by: Robert Bragg Reviewed-by: Neil Roberts (cherry picked from commit edcbeaf3c941f7a2335fbec47d5248cd9b0e8088) --- cogl/cogl-color.c | 125 ++++++++++++++++++ cogl/cogl-color.h | 38 ++++++ .../cogl-2.0-experimental-sections.txt | 4 + doc/reference/cogl/cogl-sections.txt | 4 + 4 files changed, 171 insertions(+) diff --git a/cogl/cogl-color.c b/cogl/cogl-color.c index 1f9a01ee9..7d5db0f8c 100644 --- a/cogl/cogl-color.c +++ b/cogl/cogl-color.c @@ -312,3 +312,128 @@ _cogl_color_get_rgba_4ubv (const CoglColor *color, memcpy (dest, color, 4); } +void +cogl_color_to_hsl (const CoglColor *color, + float *hue, + float *saturation, + float *luminance) +{ + float red, green, blue; + float min, max, delta; + float h, l, s; + + red = color->red / 255.0; + green = color->green / 255.0; + blue = color->blue / 255.0; + + if (red > green) + { + if (red > blue) + max = red; + else + max = blue; + + if (green < blue) + min = green; + else + min = blue; + } + else + { + if (green > blue) + max = green; + else + max = blue; + + if (red < blue) + min = red; + else + min = blue; + } + + l = (max + min) / 2; + s = 0; + h = 0; + + if (max != min) + { + if (l <= 0.5) + s = (max - min) / (max + min); + else + s = (max - min) / (2.0 - max - min); + + delta = max - min; + + if (red == max) + h = (green - blue) / delta; + else if (green == max) + h = 2.0 + (blue - red) / delta; + else if (blue == max) + h = 4.0 + (red - green) / delta; + + h *= 60; + + if (h < 0) + h += 360.0; + } + + if (hue) + *hue = h; + + if (luminance) + *luminance = l; + + if (saturation) + *saturation = s; +} + +void +cogl_color_init_from_hsl (CoglColor *color, + float hue, + float saturation, + float luminance) +{ + float tmp1, tmp2; + float tmp3[3]; + float clr[3]; + int i; + + hue /= 360.0; + + if (saturation == 0) + { + cogl_color_init_from_4f (color, luminance, luminance, luminance, 1.0f); + return; + } + + if (luminance <= 0.5) + tmp2 = luminance * (1.0 + saturation); + else + tmp2 = luminance + saturation - (luminance * saturation); + + tmp1 = 2.0 * luminance - tmp2; + + tmp3[0] = hue + 1.0 / 3.0; + tmp3[1] = hue; + tmp3[2] = hue - 1.0 / 3.0; + + for (i = 0; i < 3; i++) + { + if (tmp3[i] < 0) + tmp3[i] += 1.0; + + if (tmp3[i] > 1) + tmp3[i] -= 1.0; + + if (6.0 * tmp3[i] < 1.0) + clr[i] = tmp1 + (tmp2 - tmp1) * tmp3[i] * 6.0; + else if (2.0 * tmp3[i] < 1.0) + clr[i] = tmp2; + else if (3.0 * tmp3[i] < 2.0) + clr[i] = (tmp1 + (tmp2 - tmp1) * ((2.0 / 3.0) - tmp3[i]) * 6.0); + else + clr[i] = tmp1; + } + + cogl_color_init_from_4f (color, clr[0], clr[1], clr[2], 1.0f); +} diff --git a/cogl/cogl-color.h b/cogl/cogl-color.h index 70c034712..713f567c7 100644 --- a/cogl/cogl-color.h +++ b/cogl/cogl-color.h @@ -541,6 +541,44 @@ cogl_color_unpremultiply (CoglColor *color); CoglBool cogl_color_equal (const void *v1, const void *v2); +/** + * cogl_color_to_hsl: + * @color: a #CoglColor + * @hue: (out): return location for the hue value or %NULL + * @saturation: (out): return location for the saturation value or %NULL + * @luminance: (out): return location for the luminance value or %NULL + * + * Converts @color to the HLS format. + * + * The @hue value is in the 0 .. 360 range. The @luminance and + * @saturation values are in the 0 .. 1 range. + * + * Since: 1.16 + */ +void +cogl_color_to_hsl (const CoglColor *color, + float *hue, + float *saturation, + float *luminance); + +/** + * cogl_color_init_from_hsl: + * @color: (out): return location for a #CoglColor + * @hue: hue value, in the 0 .. 360 range + * @saturation: saturation value, in the 0 .. 1 range + * @luminance: luminance value, in the 0 .. 1 range + * + * Converts a color expressed in HLS (hue, luminance and saturation) + * values into a #CoglColor. + * + * Since: 1.16 + */ +void +cogl_color_init_from_hsl (CoglColor *color, + float hue, + float saturation, + float luminance); + COGL_END_DECLS #endif /* __COGL_COLOR_H__ */ diff --git a/doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-sections.txt b/doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-sections.txt index 00ed18ffd..4cea49ddc 100644 --- a/doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-sections.txt +++ b/doc/reference/cogl-2.0-experimental/cogl-2.0-experimental-sections.txt @@ -692,6 +692,10 @@ cogl_color_set_alpha_float cogl_color_premultiply cogl_color_unpremultiply cogl_color_equal + + +cogl_color_init_from_hsl +cogl_color_to_hsl
diff --git a/doc/reference/cogl/cogl-sections.txt b/doc/reference/cogl/cogl-sections.txt index 60db06d87..60c0048a4 100644 --- a/doc/reference/cogl/cogl-sections.txt +++ b/doc/reference/cogl/cogl-sections.txt @@ -417,6 +417,10 @@ cogl_color_set_alpha_float cogl_color_premultiply cogl_color_unpremultiply cogl_color_equal + + +cogl_color_init_from_hsl +cogl_color_to_hsl