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Initial checkin of Pika from heckimp

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2023-09-25 15:35:21 -07:00
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libpikacolor/pikacolorspace.c
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/* LIBPIKA - The PIKA Library
* Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
*
* 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 3 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
* Library 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
* <https://www.gnu.org/licenses/>.
*/
#include "config.h"
#include <babl/babl.h>
#include <glib-object.h>
#include "libpikamath/pikamath.h"
#include "pikacolortypes.h"
#include "pikacolorspace.h"
#include "pikargb.h"
#include "pikahsv.h"
/**
* SECTION: pikacolorspace
* @title: PikaColorSpace
* @short_description: Utility functions which convert colors between
* different color models.
*
* When programming pixel data manipulation functions you will often
* use algorithms operating on a color model different from the one
* PIKA uses. This file provides utility functions to convert colors
* between different color spaces.
**/
#define PIKA_HSL_UNDEFINED -1.0
/* PikaRGB functions */
/**
* pika_rgb_to_hsv:
* @rgb: A color value in the RGB colorspace
* @hsv: (out caller-allocates): The value converted to the HSV colorspace
*
* Does a conversion from RGB to HSV (Hue, Saturation,
* Value) colorspace.
**/
void
pika_rgb_to_hsv (const PikaRGB *rgb,
PikaHSV *hsv)
{
gdouble max, min, delta;
g_return_if_fail (rgb != NULL);
g_return_if_fail (hsv != NULL);
max = pika_rgb_max (rgb);
min = pika_rgb_min (rgb);
hsv->v = max;
delta = max - min;
if (delta > 0.0001)
{
hsv->s = delta / max;
if (rgb->r == max)
{
hsv->h = (rgb->g - rgb->b) / delta;
if (hsv->h < 0.0)
hsv->h += 6.0;
}
else if (rgb->g == max)
{
hsv->h = 2.0 + (rgb->b - rgb->r) / delta;
}
else
{
hsv->h = 4.0 + (rgb->r - rgb->g) / delta;
}
hsv->h /= 6.0;
}
else
{
hsv->s = 0.0;
hsv->h = 0.0;
}
hsv->a = rgb->a;
}
/**
* pika_hsv_to_rgb:
* @hsv: A color value in the HSV colorspace
* @rgb: (out caller-allocates): The returned RGB value.
*
* Converts a color value from HSV to RGB colorspace
**/
void
pika_hsv_to_rgb (const PikaHSV *hsv,
PikaRGB *rgb)
{
gint i;
gdouble f, w, q, t;
gdouble hue;
g_return_if_fail (rgb != NULL);
g_return_if_fail (hsv != NULL);
if (hsv->s == 0.0)
{
rgb->r = hsv->v;
rgb->g = hsv->v;
rgb->b = hsv->v;
}
else
{
hue = hsv->h;
if (hue == 1.0)
hue = 0.0;
hue *= 6.0;
i = (gint) hue;
f = hue - i;
w = hsv->v * (1.0 - hsv->s);
q = hsv->v * (1.0 - (hsv->s * f));
t = hsv->v * (1.0 - (hsv->s * (1.0 - f)));
switch (i)
{
case 0:
rgb->r = hsv->v;
rgb->g = t;
rgb->b = w;
break;
case 1:
rgb->r = q;
rgb->g = hsv->v;
rgb->b = w;
break;
case 2:
rgb->r = w;
rgb->g = hsv->v;
rgb->b = t;
break;
case 3:
rgb->r = w;
rgb->g = q;
rgb->b = hsv->v;
break;
case 4:
rgb->r = t;
rgb->g = w;
rgb->b = hsv->v;
break;
case 5:
rgb->r = hsv->v;
rgb->g = w;
rgb->b = q;
break;
}
}
rgb->a = hsv->a;
}
/**
* pika_rgb_to_hsl:
* @rgb: A color value in the RGB colorspace
* @hsl: (out caller-allocates): The value converted to HSL
*
* Convert an RGB color value to a HSL (Hue, Saturation, Lightness)
* color value.
**/
void
pika_rgb_to_hsl (const PikaRGB *rgb,
PikaHSL *hsl)
{
gdouble max, min, delta;
g_return_if_fail (rgb != NULL);
g_return_if_fail (hsl != NULL);
max = pika_rgb_max (rgb);
min = pika_rgb_min (rgb);
hsl->l = (max + min) / 2.0;
if (max == min)
{
hsl->s = 0.0;
hsl->h = PIKA_HSL_UNDEFINED;
}
else
{
if (hsl->l <= 0.5)
hsl->s = (max - min) / (max + min);
else
hsl->s = (max - min) / (2.0 - max - min);
delta = max - min;
if (delta == 0.0)
delta = 1.0;
if (rgb->r == max)
{
hsl->h = (rgb->g - rgb->b) / delta;
}
else if (rgb->g == max)
{
hsl->h = 2.0 + (rgb->b - rgb->r) / delta;
}
else
{
hsl->h = 4.0 + (rgb->r - rgb->g) / delta;
}
hsl->h /= 6.0;
if (hsl->h < 0.0)
hsl->h += 1.0;
}
hsl->a = rgb->a;
}
static inline gdouble
pika_hsl_value (gdouble n1,
gdouble n2,
gdouble hue)
{
gdouble val;
if (hue > 6.0)
hue -= 6.0;
else if (hue < 0.0)
hue += 6.0;
if (hue < 1.0)
val = n1 + (n2 - n1) * hue;
else if (hue < 3.0)
val = n2;
else if (hue < 4.0)
val = n1 + (n2 - n1) * (4.0 - hue);
else
val = n1;
return val;
}
/**
* pika_hsl_to_rgb:
* @hsl: A color value in the HSL colorspace
* @rgb: (out caller-allocates): The value converted to a value
* in the RGB colorspace
*
* Convert a HSL color value to an RGB color value.
**/
void
pika_hsl_to_rgb (const PikaHSL *hsl,
PikaRGB *rgb)
{
g_return_if_fail (hsl != NULL);
g_return_if_fail (rgb != NULL);
if (hsl->s == 0)
{
/* achromatic case */
rgb->r = hsl->l;
rgb->g = hsl->l;
rgb->b = hsl->l;
}
else
{
gdouble m1, m2;
if (hsl->l <= 0.5)
m2 = hsl->l * (1.0 + hsl->s);
else
m2 = hsl->l + hsl->s - hsl->l * hsl->s;
m1 = 2.0 * hsl->l - m2;
rgb->r = pika_hsl_value (m1, m2, hsl->h * 6.0 + 2.0);
rgb->g = pika_hsl_value (m1, m2, hsl->h * 6.0);
rgb->b = pika_hsl_value (m1, m2, hsl->h * 6.0 - 2.0);
}
rgb->a = hsl->a;
}
/**
* pika_rgb_to_cmyk:
* @rgb: A value in the RGB colorspace
* @pullout: A scaling value (0-1) indicating how much black should be
* pulled out
* @cmyk: (out caller-allocates): The input value naively converted
* to the CMYK colorspace
*
* Does a naive conversion from RGB to CMYK colorspace. A simple
* formula that doesn't take any color-profiles into account is used.
* The amount of black pullout how can be controlled via the @pullout
* parameter. A @pullout value of 0 makes this a conversion to CMY.
* A value of 1 causes the maximum amount of black to be pulled out.
**/
void
pika_rgb_to_cmyk (const PikaRGB *rgb,
gdouble pullout,
PikaCMYK *cmyk)
{
gdouble c, m, y, k;
g_return_if_fail (rgb != NULL);
g_return_if_fail (cmyk != NULL);
c = 1.0 - rgb->r;
m = 1.0 - rgb->g;
y = 1.0 - rgb->b;
k = 1.0;
if (c < k) k = c;
if (m < k) k = m;
if (y < k) k = y;
k *= pullout;
if (k < 1.0)
{
cmyk->c = (c - k) / (1.0 - k);
cmyk->m = (m - k) / (1.0 - k);
cmyk->y = (y - k) / (1.0 - k);
}
else
{
cmyk->c = 0.0;
cmyk->m = 0.0;
cmyk->y = 0.0;
}
cmyk->k = k;
cmyk->a = rgb->a;
}
/**
* pika_cmyk_to_rgb:
* @cmyk: A color value in the CMYK colorspace
* @rgb: (out caller-allocates): The value converted to the RGB colorspace
*
* Does a simple transformation from the CMYK colorspace to the RGB
* colorspace, without taking color profiles into account.
**/
void
pika_cmyk_to_rgb (const PikaCMYK *cmyk,
PikaRGB *rgb)
{
gdouble c, m, y, k;
g_return_if_fail (cmyk != NULL);
g_return_if_fail (rgb != NULL);
k = cmyk->k;
if (k < 1.0)
{
c = cmyk->c * (1.0 - k) + k;
m = cmyk->m * (1.0 - k) + k;
y = cmyk->y * (1.0 - k) + k;
}
else
{
c = 1.0;
m = 1.0;
y = 1.0;
}
rgb->r = 1.0 - c;
rgb->g = 1.0 - m;
rgb->b = 1.0 - y;
rgb->a = cmyk->a;
}