gimp/libgimpcolor/gimpbilinear.c

238 lines
4.5 KiB
C

/* LIBGIMP - The GIMP 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 <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "gimpcolortypes.h"
#include "gimpbilinear.h"
/**
* SECTION: gimpbilinear
* @title: GimpBilinear
* @short_description: Utility functions for bilinear interpolation.
*
* Utility functions for bilinear interpolation.
**/
gdouble
gimp_bilinear (gdouble x,
gdouble y,
gdouble *values)
{
gdouble m0, m1;
g_return_val_if_fail (values != NULL, 0.0);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0.0)
x += 1.0;
if (y < 0.0)
y += 1.0;
m0 = (1.0 - x) * values[0] + x * values[1];
m1 = (1.0 - x) * values[2] + x * values[3];
return (1.0 - y) * m0 + y * m1;
}
guchar
gimp_bilinear_8 (gdouble x,
gdouble y,
guchar *values)
{
gdouble m0, m1;
g_return_val_if_fail (values != NULL, 0);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0.0)
x += 1.0;
if (y < 0.0)
y += 1.0;
m0 = (1.0 - x) * values[0] + x * values[1];
m1 = (1.0 - x) * values[2] + x * values[3];
return (guchar) ((1.0 - y) * m0 + y * m1);
}
guint16
gimp_bilinear_16 (gdouble x,
gdouble y,
guint16 *values)
{
gdouble m0, m1;
g_return_val_if_fail (values != NULL, 0);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0.0)
x += 1.0;
if (y < 0.0)
y += 1.0;
m0 = (1.0 - x) * values[0] + x * values[1];
m1 = (1.0 - x) * values[2] + x * values[3];
return (guint16) ((1.0 - y) * m0 + y * m1);
}
guint32
gimp_bilinear_32 (gdouble x,
gdouble y,
guint32 *values)
{
gdouble m0, m1;
g_return_val_if_fail (values != NULL, 0);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0.0)
x += 1.0;
if (y < 0.0)
y += 1.0;
m0 = (1.0 - x) * values[0] + x * values[1];
m1 = (1.0 - x) * values[2] + x * values[3];
return (guint32) ((1.0 - y) * m0 + y * m1);
}
GimpRGB
gimp_bilinear_rgb (gdouble x,
gdouble y,
GimpRGB *values)
{
gdouble m0, m1;
gdouble ix, iy;
GimpRGB v = { 0, };
g_return_val_if_fail (values != NULL, v);
x = fmod(x, 1.0);
y = fmod(y, 1.0);
if (x < 0)
x += 1.0;
if (y < 0)
y += 1.0;
ix = 1.0 - x;
iy = 1.0 - y;
/* Red */
m0 = ix * values[0].r + x * values[1].r;
m1 = ix * values[2].r + x * values[3].r;
v.r = iy * m0 + y * m1;
/* Green */
m0 = ix * values[0].g + x * values[1].g;
m1 = ix * values[2].g + x * values[3].g;
v.g = iy * m0 + y * m1;
/* Blue */
m0 = ix * values[0].b + x * values[1].b;
m1 = ix * values[2].b + x * values[3].b;
v.b = iy * m0 + y * m1;
return v;
}
GimpRGB
gimp_bilinear_rgba (gdouble x,
gdouble y,
GimpRGB *values)
{
gdouble m0, m1;
gdouble ix, iy;
gdouble a0, a1, a2, a3, alpha;
GimpRGB v = { 0, };
g_return_val_if_fail (values != NULL, v);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0)
x += 1.0;
if (y < 0)
y += 1.0;
ix = 1.0 - x;
iy = 1.0 - y;
a0 = values[0].a;
a1 = values[1].a;
a2 = values[2].a;
a3 = values[3].a;
/* Alpha */
m0 = ix * a0 + x * a1;
m1 = ix * a2 + x * a3;
alpha = v.a = iy * m0 + y * m1;
if (alpha > 0)
{
/* Red */
m0 = ix * a0 * values[0].r + x * a1 * values[1].r;
m1 = ix * a2 * values[2].r + x * a3 * values[3].r;
v.r = (iy * m0 + y * m1)/alpha;
/* Green */
m0 = ix * a0 * values[0].g + x * a1 * values[1].g;
m1 = ix * a2 * values[2].g + x * a3 * values[3].g;
v.g = (iy * m0 + y * m1)/alpha;
/* Blue */
m0 = ix * a0 * values[0].b + x * a1 * values[1].b;
m1 = ix * a2 * values[2].b + x * a3 * values[3].b;
v.b = (iy * m0 + y * m1)/alpha;
}
return v;
}