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/* 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 <gegl.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.
**/
/**
* gimp_bilinear:
* @x:
* @y:
* @values: (array fixed-size=4):
*/
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;
}
/**
* gimp_bilinear_8:
* @x:
* @y:
* @values: (array fixed-size=4):
*/
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);
}
/**
* gimp_bilinear_16:
* @x:
* @y:
* @values: (array fixed-size=4):
*/
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);
}
/**
* gimp_bilinear_32:
* @x:
* @y:
* @values: (array fixed-size=4):
*/
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);
}
/**
* gimp_bilinear_rgb:
* @x:
* @y:
* @values: (array fixed-size=16): Array of pixels in RGBA double format
* @has_alpha: Whether @values has an alpha channel
* @retvalues: (array fixed-size=4): Resulting pixel
*/
void
gimp_bilinear_rgb (gdouble x,
gdouble y,
gdouble *values,
gboolean has_alpha,
gdouble *retvalues)
{
gdouble m0;
gdouble m1;
gdouble ix;
gdouble iy;
gdouble a[4] = { 1.0, 1.0, 1.0, 1.0 };
gdouble alpha = 1.0;
for (gint i = 0; i < 3; i++)
retvalues[i] = 0.0;
retvalues[3] = 1.0;
g_return_if_fail (values != NULL);
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;
if (has_alpha)
{
for (gint i = 0; i < 4; i++)
a[i] = values[(i * 4) + 3];
m0 = ix * a[0] + x * a[1];
m1 = ix * a[2] + x * a[3];
alpha = retvalues[3] = iy * m0 + y * m1;
}
if (alpha > 0)
{
for (gint i = 0; i < 3; i++)
{
m0 = ix * a[0] * values[0 + i] + x * a[1] * values[4 + i];
m1 = ix * a[2] * values[8 + i] + x * a[3] * values[12 + i];
retvalues[i] = (iy * m0 + y * m1) / alpha;
}
}
}
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