forked from AuroraMiddleware/gtk
96 lines
2.9 KiB
C
96 lines
2.9 KiB
C
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/* GdkPixbuf library - Utilities and miscellaneous convenience functions
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*
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* Copyright (C) 1999 The Free Software Foundation
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*
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* Author: Federico Mena-Quintero <federico@gimp.org>
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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 Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 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 Library General Public
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* License along with this library; if not, write to the
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* Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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* Boston, MA 02111-1307, USA.
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*/
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#include <config.h>
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#include "gdk-pixbuf/gdk-pixbuf.h"
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/**
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* gdk_pixbuf_add_alpha:
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* @pixbuf: A pixbuf.
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* @substitute_color: Whether to substitute a color for zero opacity. If this
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* is #FALSE, then the (@r, @g, @b) arguments will be ignored.
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* @r: Red value to substitute.
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* @g: Green value to substitute.
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* @b: Blue value to substitute.
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*
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* Takes an existing pixbuf and adds an alpha channel to it. If the original
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* pixbuf already had alpha information, then the contents of the new pixbuf are
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* exactly the same as the original's. Otherwise, the new pixbuf will have all
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* pixels with full opacity if @substitute_color is #FALSE. If
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* @substitute_color is #TRUE, then the color specified by (@r, @g, @b) will be
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* substituted for zero opacity.
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*
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* Return value: A newly-created pixbuf with a reference count of 1.
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**/
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GdkPixbuf *
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gdk_pixbuf_add_alpha (GdkPixbuf *pixbuf, gboolean substitute_color, guchar r, guchar g, guchar b)
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{
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ArtPixBuf *apb;
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ArtPixBuf *new_apb;
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GdkPixbuf *new_pixbuf;
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int x, y;
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g_return_val_if_fail (pixbuf != NULL, NULL);
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apb = pixbuf->art_pixbuf;
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g_return_val_if_fail (apb->format == ART_PIX_RGB, NULL);
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g_return_val_if_fail (apb->n_channels == 3 || apb->n_channels == 4, NULL);
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g_return_val_if_fail (apb->bits_per_sample == 8, NULL);
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if (apb->has_alpha) {
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new_apb = art_pixbuf_duplicate (apb);
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if (!new_apb)
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return NULL;
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return gdk_pixbuf_new_from_art_pixbuf (new_apb);
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}
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new_pixbuf = gdk_pixbuf_new (ART_PIX_RGB, TRUE, 8, apb->width, apb->height);
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if (!new_pixbuf)
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return NULL;
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new_apb = new_pixbuf->art_pixbuf;
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for (y = 0; y < apb->height; y++) {
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guchar *src, *dest;
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guchar tr, tg, tb;
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src = apb->pixels + y * apb->rowstride;
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dest = new_apb->pixels + y * new_apb->rowstride;
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for (x = 0; x < apb->width; x++) {
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tr = *dest++ = *src++;
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tg = *dest++ = *src++;
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tb = *dest++ = *src++;
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if (substitute_color && tr == r && tg == g && tb == b)
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*dest++ = 0;
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else
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*dest++ = 255;
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}
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}
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return new_pixbuf;
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}
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