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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 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
* 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, write to the
* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
* Boston, MA 02111-1307, USA.
*/
#include "config.h"
#include <glib-object.h>
#include "libgimpmath/gimpmath.h"
#include "gimpcolortypes.h"
#include "gimpbilinear.h"
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;
}
/**
* gimp_bilinear_pixels_8:
* @dest: Pixel, where interpolation result is to be stored.
* @x: x-coordinate (0.0 to 1.0).
* @y: y-coordinate (0.0 to 1.0).
* @bpp: Bytes per pixel. @dest and each @values item is an array of
* @bpp bytes.
* @has_alpha: %TRUE if the last channel is an alpha channel.
* @values: Array of four pointers to pixels.
*
* Computes bilinear interpolation of four pixels.
*
* When @has_alpha is %FALSE, it's identical to gimp_bilinear_8() on
* each channel separately. When @has_alpha is %TRUE, it handles
* alpha channel correctly.
*
* The pixels in @values correspond to corner x, y coordinates in the
* following order: [0,0], [1,0], [0,1], [1,1].
**/
void
gimp_bilinear_pixels_8 (guchar *dest,
gdouble x,
gdouble y,
guint bpp,
gboolean has_alpha,
guchar **values)
{
guint i;
g_return_if_fail (dest != NULL);
g_return_if_fail (values != NULL);
x = fmod (x, 1.0);
y = fmod (y, 1.0);
if (x < 0.0)
x += 1.0;
if (y < 0.0)
y += 1.0;
if (has_alpha)
{
guint ai = bpp - 1;
gdouble alpha0 = values[0][ai];
gdouble alpha1 = values[1][ai];
gdouble alpha2 = values[2][ai];
gdouble alpha3 = values[3][ai];
gdouble alpha = ((1.0 - y) * ((1.0 - x) * alpha0 + x * alpha1)
+ y * ((1.0 - x) * alpha2 + x * alpha3));
dest[ai] = (guchar) alpha;
if (dest[ai])
{
for (i = 0; i < ai; i++)
{
gdouble m0 = ((1.0 - x) * values[0][i] * alpha0
+ x * values[1][i] * alpha1);
gdouble m1 = ((1.0 - x) * values[2][i] * alpha2
+ x * values[3][i] * alpha3);
dest[i] = (guchar) (((1.0 - y) * m0 + y * m1) / alpha);
}
}
}
else
{
for (i = 0; i < bpp; i++)
{
gdouble m0 = (1.0 - x) * values[0][i] + x * values[1][i];
gdouble m1 = (1.0 - x) * values[2][i] + x * values[3][i];
dest[i] = (guchar) ((1.0 - y) * m0 + y * m1);
}
}
}
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