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symboliccolor: Split out HSLA code

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This commit is contained in:
Benjamin Otte
2012-11-08 15:26:33 +01:00
parent cff4718e91
commit e063a0fdf1
4 changed files with 242 additions and 165 deletions
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185
gtk/gtkhsla.c Normal file
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/* GTK - The GIMP Toolkit
* Copyright (C) 2012 Benjamin Otte <otte@gnome.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "gtkhslaprivate.h"
#include <math.h>
void
_gtk_hsla_init (GtkHSLA *hsla,
double hue,
double saturation,
double lightness,
double alpha)
{
g_return_if_fail (hsla != NULL);
if (hue >= 0)
hsla->hue = fmod (hue, 360);
else
hsla->hue = fmod (hue, 360) + 360;
hsla->saturation = CLAMP (saturation, 0, 1);
hsla->lightness = CLAMP (lightness, 0, 1);
hsla->alpha = CLAMP (alpha, 0, 1);
}
void
_gtk_hsla_init_from_rgba (GtkHSLA *hsla,
const GdkRGBA *rgba)
{
gdouble min;
gdouble max;
gdouble red;
gdouble green;
gdouble blue;
gdouble delta;
g_return_if_fail (hsla != NULL);
g_return_if_fail (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->lightness = (max + min) / 2;
hsla->saturation = 0;
hsla->hue = 0;
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;
}
}
void
_gdk_rgba_init_from_hsla (GdkRGBA *rgba,
const GtkHSLA *hsla)
{
gdouble hue;
gdouble lightness;
gdouble saturation;
gdouble m1, m2;
lightness = hsla->lightness;
saturation = hsla->saturation;
if (lightness <= 0.5)
m2 = lightness * (1 + saturation);
else
m2 = lightness + saturation - lightness * saturation;
m1 = 2 * lightness - m2;
rgba->alpha = hsla->alpha;
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;
}
}