New file with utility and convenience functions for pixbufs.

1999-12-02  Federico Mena Quintero  <federico@redhat.com>

	* src/gdk-pixbuf-util.c: New file with utility and convenience
	functions for pixbufs.

	* src/Makefile.am (libgdk_pixbuf_la_SOURCES): Added gdk-pixbuf-util.c.

	* doc/gdk-pixbuf-sections.txt: Added section for utility functions.

	* doc/Makefile.am (tmpl_sources): Added tmpl/util.sgml.

	* doc/gdk-pixbuf.sgml: Added the utilities section.

	* doc/tmpl/util.sgml: Documentation for the utility functions.

1 files changed, 95 insertions, 0 deletions

diff --git a/gdk-pixbuf/gdk-pixbuf-util.c b/gdk-pixbuf/gdk-pixbuf-util.c
new file mode 100644
index 0000000000..c274c30f56
--- /dev/null
+++ b/gdk-pixbuf/gdk-pixbuf-util.c
@@ -0,0 +1,95 @@
+/* GdkPixbuf library - Utilities and miscellaneous convenience functions
+ *
+ * Copyright (C) 1999 The Free Software Foundation
+ *
+ * Author: Federico Mena-Quintero <federico@gimp.org>
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Library 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 Library 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 "gdk-pixbuf/gdk-pixbuf.h"
+
+
+
+/**
+ * gdk_pixbuf_add_alpha:
+ * @pixbuf: A pixbuf.
+ * @substitute_color: Whether to substitute a color for zero opacity.  If this
+ * is #FALSE, then the (@r, @g, @b) arguments will be ignored.
+ * @r: Red value to substitute.
+ * @g: Green value to substitute.
+ * @b: Blue value to substitute.
+ *
+ * Takes an existing pixbuf and adds an alpha channel to it.  If the original
+ * pixbuf already had alpha information, then the contents of the new pixbuf are
+ * exactly the same as the original's.  Otherwise, the new pixbuf will have all
+ * pixels with full opacity if @substitute_color is #FALSE.  If
+ * @substitute_color is #TRUE, then the color specified by (@r, @g, @b) will be
+ * substituted for zero opacity.
+ *
+ * Return value: A newly-created pixbuf with a reference count of 1.
+ **/
+GdkPixbuf *
+gdk_pixbuf_add_alpha (GdkPixbuf *pixbuf, gboolean substitute_color, guchar r, guchar g, guchar b)
+{
+	ArtPixBuf *apb;
+	ArtPixBuf *new_apb;
+	GdkPixbuf *new_pixbuf;
+	int x, y;
+
+	g_return_val_if_fail (pixbuf != NULL, NULL);
+
+	apb = pixbuf->art_pixbuf;
+	g_return_val_if_fail (apb->format == ART_PIX_RGB, NULL);
+	g_return_val_if_fail (apb->n_channels == 3 || apb->n_channels == 4, NULL);
+	g_return_val_if_fail (apb->bits_per_sample == 8, NULL);
+
+	if (apb->has_alpha) {
+		new_apb = art_pixbuf_duplicate (apb);
+		if (!new_apb)
+			return NULL;
+
+		return gdk_pixbuf_new_from_art_pixbuf (new_apb);
+	}
+
+	new_pixbuf = gdk_pixbuf_new (ART_PIX_RGB, TRUE, 8, apb->width, apb->height);
+	if (!new_pixbuf)
+		return NULL;
+
+	new_apb = new_pixbuf->art_pixbuf;
+
+	for (y = 0; y < apb->height; y++) {
+		guchar *src, *dest;
+		guchar tr, tg, tb;
+
+		src = apb->pixels + y * apb->rowstride;
+		dest = new_apb->pixels + y * new_apb->rowstride;
+
+		for (x = 0; x < apb->width; x++) {
+			tr = *dest++ = *src++;
+			tg = *dest++ = *src++;
+			tb = *dest++ = *src++;
+
+			if (substitute_color && tr == r && tg == g && tb == b)
+				*dest++ = 0;
+			else
+				*dest++ = 255;
+		}
+	}
+
+	return new_pixbuf;
+}