gtk2/gtk/gtkcolorutils.c
2018-04-11 03:11:22 +02:00

256 lines
4.9 KiB
C

/* Color utilities
*
* Copyright (C) 1999 The Free Software Foundation
*
* Authors: Simon Budig <Simon.Budig@unix-ag.org> (original code)
* Federico Mena-Quintero <federico@gimp.org> (cleanup for GTK+)
* Jonathan Blandford <jrb@redhat.com> (cleanup for GTK+)
*
* 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/>.
*/
/*
* Modified by the GTK+ Team and others 1997-2000. See the AUTHORS
* file for a list of people on the GTK+ Team. See the ChangeLog
* files for a list of changes. These files are distributed with
* GTK+ at ftp://ftp.gtk.org/pub/gtk/.
*/
#include "config.h"
#include <math.h>
#include <string.h>
#include "gtkcolorutils.h"
/* Converts from HSV to RGB */
static void
hsv_to_rgb (gdouble *h,
gdouble *s,
gdouble *v)
{
gdouble hue, saturation, value;
gdouble f, p, q, t;
if (*s == 0.0)
{
*h = *v;
*s = *v;
*v = *v; /* heh */
}
else
{
hue = *h * 6.0;
saturation = *s;
value = *v;
if (hue == 6.0)
hue = 0.0;
f = hue - (int) hue;
p = value * (1.0 - saturation);
q = value * (1.0 - saturation * f);
t = value * (1.0 - saturation * (1.0 - f));
switch ((int) hue)
{
case 0:
*h = value;
*s = t;
*v = p;
break;
case 1:
*h = q;
*s = value;
*v = p;
break;
case 2:
*h = p;
*s = value;
*v = t;
break;
case 3:
*h = p;
*s = q;
*v = value;
break;
case 4:
*h = t;
*s = p;
*v = value;
break;
case 5:
*h = value;
*s = p;
*v = q;
break;
default:
g_assert_not_reached ();
}
}
}
/* Converts from RGB to HSV */
static void
rgb_to_hsv (gdouble *r,
gdouble *g,
gdouble *b)
{
gdouble red, green, blue;
gdouble h, s, v;
gdouble min, max;
gdouble delta;
red = *r;
green = *g;
blue = *b;
h = 0.0;
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;
}
v = max;
if (max != 0.0)
s = (max - min) / max;
else
s = 0.0;
if (s == 0.0)
h = 0.0;
else
{
delta = max - min;
if (red == max)
h = (green - blue) / delta;
else if (green == max)
h = 2 + (blue - red) / delta;
else if (blue == max)
h = 4 + (red - green) / delta;
h /= 6.0;
if (h < 0.0)
h += 1.0;
else if (h > 1.0)
h -= 1.0;
}
*r = h;
*g = s;
*b = v;
}
/**
* gtk_hsv_to_rgb:
* @h: Hue
* @s: Saturation
* @v: Value
* @r: (out): Return value for the red component
* @g: (out): Return value for the green component
* @b: (out): Return value for the blue component
*
* Converts a color from HSV space to RGB.
*
* Input values must be in the [0.0, 1.0] range;
* output values will be in the same range.
*
* Since: 2.14
*/
void
gtk_hsv_to_rgb (gdouble h, gdouble s, gdouble v,
gdouble *r, gdouble *g, gdouble *b)
{
g_return_if_fail (h >= 0.0 && h <= 1.0);
g_return_if_fail (s >= 0.0 && s <= 1.0);
g_return_if_fail (v >= 0.0 && v <= 1.0);
hsv_to_rgb (&h, &s, &v);
if (r)
*r = h;
if (g)
*g = s;
if (b)
*b = v;
}
/**
* gtk_rgb_to_hsv:
* @r: Red
* @g: Green
* @b: Blue
* @h: (out): Return value for the hue component
* @s: (out): Return value for the saturation component
* @v: (out): Return value for the value component
*
* Converts a color from RGB space to HSV.
*
* Input values must be in the [0.0, 1.0] range;
* output values will be in the same range.
*
* Since: 2.14
*/
void
gtk_rgb_to_hsv (gdouble r, gdouble g, gdouble b,
gdouble *h, gdouble *s, gdouble *v)
{
g_return_if_fail (r >= 0.0 && r <= 1.0);
g_return_if_fail (g >= 0.0 && g <= 1.0);
g_return_if_fail (b >= 0.0 && b <= 1.0);
rgb_to_hsv (&r, &g, &b);
if (h)
*h = r;
if (s)
*s = g;
if (v)
*v = b;
}