source: trunk/third/bonobo/bonobo/bonobo-ui-icon-modify.c @ 17169

/* bonobo-ui-icon-modify.h: Icon modifier for the Bonobo UI engine
 *
 * Copyright (C) 2001 Ximian, Inc.
 *
 * Author: Federico Mena-Quintero <federico@ximian.com>
 *
 * 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.
 */

#ifdef HAVE_CONFIG_H
#include <config.h>
#endif

#include "bonobo-ui-icon-modify.h"



/**
 * bonobo_ui_icon_modify:
 * @source: A pixbuf.
 * @saturation: Saturation value for the new image.  1.0 means full saturation and
 * leaves the original colors untouched.  0.0 means full desaturation and effectively
 * converts the image to grayscale.
 * @pixelate: Whether to apply a 50% dark stipple pattern to the destination image.
 * @pixelation_dark_factor: If @pixelate is TRUE, then the stipple pattern will
 * be created using the colors of the original image darkened by this factor.
 * 0.0 is completely black and 1.0 leaves the original colors untouched.
 * 
 * Modifies a @source pixbuf for use as a menu/toolbar icon by optionally
 * desaturating and applying a dark stipple pattern to it.
 * 
 * Return value: The generated, modified image or NULL if it could not be
 * created.
 **/
GdkPixbuf *
bonobo_ui_icon_modify (GdkPixbuf *source, double saturation,
                       gboolean pixelate, double pixelation_dark_factor)
{
        GdkPixbuf *dest;
        int width, height, source_rowstride, n_channels;
        int dest_rowstride;
        gboolean has_alpha;
        int x, y;
        guchar *src_row, *dest_row;

        g_return_val_if_fail (source != NULL, NULL);
        g_return_val_if_fail (gdk_pixbuf_get_colorspace (source) == GDK_COLORSPACE_RGB, NULL);

        n_channels = gdk_pixbuf_get_n_channels (source);
        has_alpha = gdk_pixbuf_get_has_alpha (source);

        g_assert ((!has_alpha && n_channels == 3) || (has_alpha && n_channels == 4));

        width = gdk_pixbuf_get_width (source);
        height = gdk_pixbuf_get_height (source);
        source_rowstride = gdk_pixbuf_get_rowstride (source);

        dest = gdk_pixbuf_new (GDK_COLORSPACE_RGB, has_alpha, 8, width, height);
        if (!dest)
                return NULL;

        dest_rowstride = gdk_pixbuf_get_rowstride (dest);

        src_row = gdk_pixbuf_get_pixels (source);
        dest_row = gdk_pixbuf_get_pixels (dest);

        for (y = 0; y < height; y++) {
                guchar *s, *d;

                s = src_row;
                d = dest_row;

                for (x = 0; x < width; x++) {
                        int r, g, b;

                        r = *s++;
                        g = *s++;
                        b = *s++;

                        /* Desaturate */

                        if (saturation != 1.0) {
                                int intensity;

                                intensity = r * 0.30 + g * 0.59 + b * 0.11 + 0.5;

                                r = intensity + (r - intensity) * saturation + 0.5;
                                g = intensity + (g - intensity) * saturation + 0.5;
                                b = intensity + (b - intensity) * saturation + 0.5;
                        }

                        /* Pixelate if needed */

                        if (pixelate && ((x + y) % 2) == 0) {
                                r = r * pixelation_dark_factor + 0.5;
                                g = g * pixelation_dark_factor + 0.5;
                                b = b * pixelation_dark_factor + 0.5;
                        }

                        /* Set destination pixel */
                        
                        *d++ = CLAMP (r, 0, 255);
                        *d++ = CLAMP (g, 0, 255);
                        *d++ = CLAMP (b, 0, 255);

                        if (has_alpha)
                                *d++ = *s++;
                }

                src_row += source_rowstride;
                dest_row += dest_rowstride;
        }

        return dest;
}