forked from openkylin/gimp
314 lines
6.6 KiB
C
314 lines
6.6 KiB
C
/* LIBGIMP - The GIMP Library
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* Copyright (C) 1995-1997 Peter Mattis and Spencer Kimball
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*
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* This library is free software: you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 3 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library. If not, see
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* <https://www.gnu.org/licenses/>.
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*/
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#include "config.h"
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#include <glib-object.h>
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#include "libgimpmath/gimpmath.h"
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#include "gimpcolortypes.h"
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#include "gimpbilinear.h"
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/**
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* SECTION: gimpbilinear
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* @title: GimpBilinear
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* @short_description: Utility functions for bilinear interpolation.
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*
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* Utility functions for bilinear interpolation.
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**/
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gdouble
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gimp_bilinear (gdouble x,
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gdouble y,
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gdouble *values)
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{
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gdouble m0, m1;
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g_return_val_if_fail (values != NULL, 0.0);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0.0)
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x += 1.0;
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if (y < 0.0)
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y += 1.0;
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m0 = (1.0 - x) * values[0] + x * values[1];
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m1 = (1.0 - x) * values[2] + x * values[3];
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return (1.0 - y) * m0 + y * m1;
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}
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guchar
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gimp_bilinear_8 (gdouble x,
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gdouble y,
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guchar *values)
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{
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gdouble m0, m1;
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g_return_val_if_fail (values != NULL, 0);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0.0)
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x += 1.0;
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if (y < 0.0)
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y += 1.0;
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m0 = (1.0 - x) * values[0] + x * values[1];
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m1 = (1.0 - x) * values[2] + x * values[3];
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return (guchar) ((1.0 - y) * m0 + y * m1);
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}
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guint16
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gimp_bilinear_16 (gdouble x,
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gdouble y,
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guint16 *values)
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{
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gdouble m0, m1;
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g_return_val_if_fail (values != NULL, 0);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0.0)
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x += 1.0;
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if (y < 0.0)
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y += 1.0;
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m0 = (1.0 - x) * values[0] + x * values[1];
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m1 = (1.0 - x) * values[2] + x * values[3];
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return (guint16) ((1.0 - y) * m0 + y * m1);
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}
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guint32
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gimp_bilinear_32 (gdouble x,
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gdouble y,
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guint32 *values)
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{
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gdouble m0, m1;
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g_return_val_if_fail (values != NULL, 0);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0.0)
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x += 1.0;
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if (y < 0.0)
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y += 1.0;
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m0 = (1.0 - x) * values[0] + x * values[1];
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m1 = (1.0 - x) * values[2] + x * values[3];
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return (guint32) ((1.0 - y) * m0 + y * m1);
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}
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GimpRGB
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gimp_bilinear_rgb (gdouble x,
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gdouble y,
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GimpRGB *values)
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{
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gdouble m0, m1;
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gdouble ix, iy;
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GimpRGB v = { 0, };
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g_return_val_if_fail (values != NULL, v);
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x = fmod(x, 1.0);
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y = fmod(y, 1.0);
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if (x < 0)
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x += 1.0;
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if (y < 0)
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y += 1.0;
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ix = 1.0 - x;
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iy = 1.0 - y;
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/* Red */
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m0 = ix * values[0].r + x * values[1].r;
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m1 = ix * values[2].r + x * values[3].r;
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v.r = iy * m0 + y * m1;
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/* Green */
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m0 = ix * values[0].g + x * values[1].g;
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m1 = ix * values[2].g + x * values[3].g;
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v.g = iy * m0 + y * m1;
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/* Blue */
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m0 = ix * values[0].b + x * values[1].b;
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m1 = ix * values[2].b + x * values[3].b;
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v.b = iy * m0 + y * m1;
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return v;
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}
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GimpRGB
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gimp_bilinear_rgba (gdouble x,
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gdouble y,
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GimpRGB *values)
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{
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gdouble m0, m1;
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gdouble ix, iy;
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gdouble a0, a1, a2, a3, alpha;
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GimpRGB v = { 0, };
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g_return_val_if_fail (values != NULL, v);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0)
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x += 1.0;
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if (y < 0)
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y += 1.0;
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ix = 1.0 - x;
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iy = 1.0 - y;
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a0 = values[0].a;
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a1 = values[1].a;
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a2 = values[2].a;
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a3 = values[3].a;
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/* Alpha */
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m0 = ix * a0 + x * a1;
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m1 = ix * a2 + x * a3;
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alpha = v.a = iy * m0 + y * m1;
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if (alpha > 0)
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{
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/* Red */
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m0 = ix * a0 * values[0].r + x * a1 * values[1].r;
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m1 = ix * a2 * values[2].r + x * a3 * values[3].r;
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v.r = (iy * m0 + y * m1)/alpha;
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/* Green */
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m0 = ix * a0 * values[0].g + x * a1 * values[1].g;
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m1 = ix * a2 * values[2].g + x * a3 * values[3].g;
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v.g = (iy * m0 + y * m1)/alpha;
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/* Blue */
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m0 = ix * a0 * values[0].b + x * a1 * values[1].b;
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m1 = ix * a2 * values[2].b + x * a3 * values[3].b;
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v.b = (iy * m0 + y * m1)/alpha;
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}
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return v;
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}
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/**
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* gimp_bilinear_pixels_8:
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* @dest: Pixel, where interpolation result is to be stored.
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* @x: x-coordinate (0.0 to 1.0).
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* @y: y-coordinate (0.0 to 1.0).
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* @bpp: Bytes per pixel. @dest and each @values item is an array of
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* @bpp bytes.
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* @has_alpha: %TRUE if the last channel is an alpha channel.
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* @values: Array of four pointers to pixels.
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*
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* Computes bilinear interpolation of four pixels.
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*
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* When @has_alpha is %FALSE, it's identical to gimp_bilinear_8() on
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* each channel separately. When @has_alpha is %TRUE, it handles
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* alpha channel correctly.
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*
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* The pixels in @values correspond to corner x, y coordinates in the
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* following order: [0,0], [1,0], [0,1], [1,1].
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**/
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void
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gimp_bilinear_pixels_8 (guchar *dest,
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gdouble x,
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gdouble y,
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guint bpp,
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gboolean has_alpha,
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guchar **values)
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{
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guint i;
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g_return_if_fail (dest != NULL);
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g_return_if_fail (values != NULL);
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x = fmod (x, 1.0);
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y = fmod (y, 1.0);
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if (x < 0.0)
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x += 1.0;
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if (y < 0.0)
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y += 1.0;
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if (has_alpha)
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{
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guint ai = bpp - 1;
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gdouble alpha0 = values[0][ai];
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gdouble alpha1 = values[1][ai];
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gdouble alpha2 = values[2][ai];
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gdouble alpha3 = values[3][ai];
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gdouble alpha = ((1.0 - y) * ((1.0 - x) * alpha0 + x * alpha1)
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+ y * ((1.0 - x) * alpha2 + x * alpha3));
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dest[ai] = (guchar) alpha;
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if (dest[ai])
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{
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for (i = 0; i < ai; i++)
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{
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gdouble m0 = ((1.0 - x) * values[0][i] * alpha0
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+ x * values[1][i] * alpha1);
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gdouble m1 = ((1.0 - x) * values[2][i] * alpha2
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+ x * values[3][i] * alpha3);
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dest[i] = (guchar) (((1.0 - y) * m0 + y * m1) / alpha);
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}
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}
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}
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else
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{
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for (i = 0; i < bpp; i++)
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{
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gdouble m0 = (1.0 - x) * values[0][i] + x * values[1][i];
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gdouble m1 = (1.0 - x) * values[2][i] + x * values[3][i];
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dest[i] = (guchar) ((1.0 - y) * m0 + y * m1);
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}
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}
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}
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