147 lines
2.9 KiB
C
147 lines
2.9 KiB
C
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#include <gdk/gdk.h>
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#include "hsla.h"
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void
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_gdk_hsla_init_from_rgba (GdkHSLA *hsla,
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const GdkRGBA *rgba)
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{
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float min;
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float max;
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float red;
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float green;
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float blue;
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float delta;
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g_return_if_fail (hsla != NULL);
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g_return_if_fail (rgba != NULL);
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red = rgba->red;
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green = rgba->green;
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blue = rgba->blue;
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if (red > green)
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{
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if (red > blue)
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max = red;
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else
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max = blue;
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if (green < blue)
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min = green;
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else
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min = blue;
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}
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else
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{
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if (green > blue)
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max = green;
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else
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max = blue;
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if (red < blue)
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min = red;
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else
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min = blue;
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}
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hsla->lightness = (max + min) / 2;
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hsla->saturation = 0;
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hsla->hue = 0;
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hsla->alpha = rgba->alpha;
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if (max != min)
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{
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if (hsla->lightness <= 0.5)
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hsla->saturation = (max - min) / (max + min);
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else
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hsla->saturation = (max - min) / (2 - max - min);
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delta = max -min;
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if (red == max)
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hsla->hue = (green - blue) / delta;
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else if (green == max)
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hsla->hue = 2 + (blue - red) / delta;
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else if (blue == max)
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hsla->hue = 4 + (red - green) / delta;
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hsla->hue *= 60;
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if (hsla->hue < 0.0)
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hsla->hue += 360;
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}
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}
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void
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_gdk_rgba_init_from_hsla (GdkRGBA *rgba,
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const GdkHSLA *hsla)
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{
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float hue;
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float lightness;
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float saturation;
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float m1, m2;
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lightness = hsla->lightness;
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saturation = hsla->saturation;
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if (lightness <= 0.5)
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m2 = lightness * (1 + saturation);
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else
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m2 = lightness + saturation - lightness * saturation;
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m1 = 2 * lightness - m2;
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rgba->alpha = hsla->alpha;
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if (saturation == 0)
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{
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rgba->red = lightness;
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rgba->green = lightness;
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rgba->blue = lightness;
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}
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else
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{
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hue = hsla->hue + 120;
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while (hue > 360)
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hue -= 360;
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while (hue < 0)
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hue += 360;
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if (hue < 60)
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rgba->red = m1 + (m2 - m1) * hue / 60;
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else if (hue < 180)
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rgba->red = m2;
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else if (hue < 240)
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rgba->red = m1 + (m2 - m1) * (240 - hue) / 60;
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else
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rgba->red = m1;
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hue = hsla->hue;
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while (hue > 360)
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hue -= 360;
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while (hue < 0)
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hue += 360;
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if (hue < 60)
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rgba->green = m1 + (m2 - m1) * hue / 60;
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else if (hue < 180)
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rgba->green = m2;
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else if (hue < 240)
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rgba->green = m1 + (m2 - m1) * (240 - hue) / 60;
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else
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rgba->green = m1;
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hue = hsla->hue - 120;
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while (hue > 360)
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hue -= 360;
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while (hue < 0)
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hue += 360;
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if (hue < 60)
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rgba->blue = m1 + (m2 - m1) * hue / 60;
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else if (hue < 180)
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rgba->blue = m2;
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else if (hue < 240)
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rgba->blue = m1 + (m2 - m1) * (240 - hue) / 60;
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else
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rgba->blue = m1;
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}
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}
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