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/*
* Copyright (C) 2001 Havoc Pennington
* Copyright (C) 2016 Alberts Muktupāvels
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "meta-hsla-private.h"
/**
* meta_hsla_from_rgba:
* @hsla: (out): location to store #MetaHSLA color
* @rgba: #GdkRGBA color
*
* Convert RGBA color to HSLA color.
*/
void
meta_hsla_from_rgba (MetaHSLA *hsla,
const GdkRGBA *rgba)
{
gdouble min;
gdouble max;
gdouble red;
gdouble green;
gdouble blue;
gdouble delta;
g_return_if_fail (hsla != NULL || rgba != NULL);
red = rgba->red;
green = rgba->green;
blue = rgba->blue;
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;
}
hsla->hue = 0;
hsla->saturation = 0;
hsla->lightness = (max + min) / 2;
hsla->alpha = rgba->alpha;
if (max != min)
{
if (hsla->lightness <= 0.5)
hsla->saturation = (max - min) / (max + min);
else
hsla->saturation = (max - min) / (2 - max - min);
delta = max - min;
if (red == max)
hsla->hue = (green - blue) / delta;
else if (green == max)
hsla->hue = 2 + (blue - red) / delta;
else if (blue == max)
hsla->hue = 4 + (red - green) / delta;
hsla->hue *= 60;
if (hsla->hue < 0.0)
hsla->hue += 360;
}
}
/**
* meta_hsla_to_rgba:
* @hsla: #MetaHSLA color
* @rgba: (out): location to store #GdkRGBA color
*
* Convert HSLA color to RGBA color.
*/
void
meta_hsla_to_rgba (const MetaHSLA *hsla,
GdkRGBA *rgba)
{
gdouble hue;
gdouble saturation;
gdouble lightness;
gdouble m1;
gdouble m2;
g_return_if_fail (hsla != NULL || rgba != NULL);
saturation = hsla->saturation;
lightness = hsla->lightness;
if (lightness <= 0.5)
m2 = lightness * (1 + saturation);
else
m2 = lightness + saturation - lightness * saturation;
m1 = 2 * lightness - m2;
if (saturation == 0)
{
rgba->red = lightness;
rgba->green = lightness;
rgba->blue = lightness;
}
else
{
hue = hsla->hue + 120;
while (hue > 360)
hue -= 360;
while (hue < 0)
hue += 360;
if (hue < 60)
rgba->red = m1 + (m2 - m1) * hue / 60;
else if (hue < 180)
rgba->red = m2;
else if (hue < 240)
rgba->red = m1 + (m2 - m1) * (240 - hue) / 60;
else
rgba->red = m1;
hue = hsla->hue;
while (hue > 360)
hue -= 360;
while (hue < 0)
hue += 360;
if (hue < 60)
rgba->green = m1 + (m2 - m1) * hue / 60;
else if (hue < 180)
rgba->green = m2;
else if (hue < 240)
rgba->green = m1 + (m2 - m1) * (240 - hue) / 60;
else
rgba->green = m1;
hue = hsla->hue - 120;
while (hue > 360)
hue -= 360;
while (hue < 0)
hue += 360;
if (hue < 60)
rgba->blue = m1 + (m2 - m1) * hue / 60;
else if (hue < 180)
rgba->blue = m2;
else if (hue < 240)
rgba->blue = m1 + (m2 - m1) * (240 - hue) / 60;
else
rgba->blue = m1;
}
rgba->alpha = hsla->alpha;
}
/**
* meta_hsla_shade:
* @source: #MetaHSLA color
* @factor: amount to scale saturation and lightness
* @destination: (out): location to store #MetaHSLA color
*
* Takes a @source color, scales saturation and lightness by @factor and
* sets @destionation to the resulting color.
*/
void
meta_hsla_shade (const MetaHSLA *source,
const gdouble factor,
MetaHSLA *destination)
{
g_return_if_fail (source != NULL || destination != NULL);
destination->hue = source->hue;
destination->saturation = source->saturation * factor;
destination->saturation = CLAMP (destination->saturation, 0.0, 1.0);
destination->lightness = source->lightness * factor;
destination->lightness = CLAMP (destination->lightness, 0.0, 1.0);
destination->alpha = source->alpha;
}
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