gtk/gdk/gdkpixbuf-render.c

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/* GdkPixbuf library - Rendering 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/gdk.h>
Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) 2000-04-11 Federico Mena Quintero <federico@helixcode.com> Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) to make GdkPixbuf's structures opaque and to remove the libart dependency. * gdk-pixbuf/gdk-pixbuf.h: Removed the public structures. (GdkColorspace): New enum that for now only contains GDK_COLORSPACE_RGB. (GdkPixbufDestroyNotify): New type for the pixbuf's pixels destroy notification function. (GdkInterpType): New num with interpolation types. * *.[ch]: Replace the libart stuff with our own stuff. * pixops/*.[ch]: Likewise. * gdk-pixbuf/gdk-pixbuf-private.h: New file with the private declarations of the GdkPixbuf structures. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_new_from_art_pixbuf): Removed function. (gdk_pixbuf_get_format): Constify. (gdk_pixbuf_get_n_channels): Constify. (gdk_pixbuf_get_has_alpha): Constify. (gdk_pixbuf_get_bits_per_sample): Constify. (gdk_pixbuf_get_pixels): Constify. (gdk_pixbuf_get_width): Constify. (gdk_pixbuf_get_height): Constify. (gdk_pixbuf_get_rowstride): Constify. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_copy): New function to copy a pixbuf. * gdk-pixbuf/gdk-pixbuf-data.c (gdk_pixbuf_new_from_data): Added a bits_per_sample argument; currently only 8 bits per sample are supported. * gdk-pixbuf/gdk-pixbuf-animation.c (gdk_pixbuf_frame_get_pixbuf): New accessor. (gdk_pixbuf_frame_get_x_offset): New accessor. (gdk_pixbuf_frame_get_y_offset): New accessor. (gdk_pixbuf_frame_get_delay_time): New accessor. (gdk_pixbuf_frame_get_action): New accessor. * gdk-pixbuf/gdk-pixbuf-render.c (gdk_pixbuf_render_pixmap_and_mask): Instead of returning a solid mask rectangle for pixbufs without an alpha channel, set the *mask_return to NULL. * gdk-pixbuf/gdk-pixbuf-util.c (gdk_pixbuf_add_alpha): Constify. * gdk-pixbuf/gdk-pixbuf-scale.c: Fix includes. * gdk-pixbuf/gdk-pixbuf-scale.c (gdk_pixbuf_scale): Added some preconditions. Maybe we should also check for the colorspace, bits per pixel, and such. (gdk_pixbuf_composite): Likewise. (gdk_pixbuf_composite_color): Likewise. (gdk_pixbuf_scale_simple): Likewise, and fail gracefully if we cannot allocate the new pixbuf. (gdk_pixbuf_composite_color_simple): Likewise. * gdk-pixbuf/gnome-canvas-pixbuf.c (gnome_canvas_pixbuf_render): Use art_rgb_rgba_affine() or art_rgb_affine() since we no longer have an ArtPixBuf. * gdk-pixbuf/io-bmp.c: Fix includes. * gdk-pixbuf/pixops/pixops.c (pixops_scale_nearest): Fixed cast in an lvalue. * TODO: Populated. * configure.in: Removed checks for libart. * gdk-pixbuf/Makefile.am: Removed references to libart. (noinst_HEADERS): Added gdk-pixbuf-private.h. * gdk-pixbuf/Makefile.am (libgdk_pixbuf_la_LDFLAGS): Incremented the version number of the libtool library to indicate that this definitely is not compatible with the old usage. I know you love me. I know you do. * configure.in: Bumped version number to 0.7.0. * README: Updated. * gdk-pixbuf-config.in (--libs): We no longer require libart. * DEPENDS.libgdk_pixbuf: We no longer depend on libart. * gdk-pixbuf.spec.in: Updated, but I don't guarantee anything.
2000-04-11 07:03:25 +00:00
#include "gdk-pixbuf-private.h"
#include "gdkpixbuf.h"
/**
* gdk_pixbuf_render_threshold_alpha:
* @pixbuf: A pixbuf.
* @bitmap: Bitmap where the bilevel mask will be painted to.
* @src_x: Source X coordinate.
* @src_y: source Y coordinate.
* @dest_x: Destination X coordinate.
* @dest_y: Destination Y coordinate.
* @width: Width of region to threshold.
* @height: Height of region to threshold.
* @alpha_threshold: Opacity values below this will be painted as zero; all
* other values will be painted as one.
*
* Takes the opacity values in a rectangular portion of a pixbuf and thresholds
* them to produce a bi-level alpha mask that can be used as a clipping mask for
* a drawable.
*
**/
void
gdk_pixbuf_render_threshold_alpha (GdkPixbuf *pixbuf,
GdkBitmap *bitmap,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
int alpha_threshold)
{
GdkGC *gc;
GdkColor color;
int x, y;
guchar *p;
int start, start_status;
int status;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (bitmap != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
g_return_if_fail (alpha_threshold >= 0 && alpha_threshold <= 255);
if (width == 0 || height == 0)
return;
gc = gdk_gc_new (bitmap);
if (!pixbuf->has_alpha)
{
color.pixel = (alpha_threshold == 255) ? 0 : 1;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
gdk_gc_unref (gc);
return;
}
color.pixel = 0;
gdk_gc_set_foreground (gc, &color);
gdk_draw_rectangle (bitmap, gc, TRUE, dest_x, dest_y, width, height);
color.pixel = 1;
gdk_gc_set_foreground (gc, &color);
for (y = 0; y < height; y++)
{
p = (pixbuf->pixels + (y + src_y) * pixbuf->rowstride + src_x * pixbuf->n_channels
+ pixbuf->n_channels - 1);
start = 0;
start_status = *p < alpha_threshold;
for (x = 0; x < width; x++)
{
status = *p < alpha_threshold;
if (status != start_status)
{
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
start = x;
start_status = status;
}
p += pixbuf->n_channels;
}
if (!start_status)
gdk_draw_line (bitmap, gc,
start + dest_x, y + dest_y,
x - 1 + dest_x, y + dest_y);
}
gdk_gc_unref (gc);
}
/* Creates a buffer by stripping the alpha channel of a pixbuf */
static guchar *
remove_alpha (GdkPixbuf *pixbuf,
int x, int y,
int width, int height,
int *rowstride)
{
guchar *buf;
int xx, yy;
guchar *src, *dest;
g_assert (pixbuf->n_channels == 4);
g_assert (pixbuf->has_alpha);
g_assert (width > 0 && height > 0);
g_assert (x >= 0 && x + width <= pixbuf->width);
g_assert (y >= 0 && y + height <= pixbuf->height);
*rowstride = 4 * ((width * 3 + 3) / 4);
buf = g_new (guchar, *rowstride * height);
for (yy = 0; yy < height; yy++)
{
src = pixbuf->pixels + pixbuf->rowstride * (yy + y) + x * pixbuf->n_channels;
dest = buf + *rowstride * yy;
for (xx = 0; xx < width; xx++)
{
*dest++ = *src++;
*dest++ = *src++;
*dest++ = *src++;
src++;
}
}
return buf;
}
/**
* gdk_pixbuf_render_to_drawable:
* @pixbuf: A pixbuf.
* @drawable: Destination drawable.
* @gc: GC used for rendering.
* @src_x: Source X coordinate within pixbuf.
* @src_y: Source Y coordinate within pixbuf.
* @dest_x: Destination X coordinate within drawable.
* @dest_y: Destination Y coordinate within drawable.
* @width: Width of region to render, in pixels.
* @height: Height of region to render, in pixels.
* @dither: Dithering mode for GdkRGB.
* @x_dither: X offset for dither.
* @y_dither: Y offset for dither.
*
* Renders a rectangular portion of a pixbuf to a drawable while using the
* specified GC. This is done using GdkRGB, so the specified drawable must have
* the GdkRGB visual and colormap. Note that this function will ignore the
* opacity information for images with an alpha channel; the GC must already
* have the clipping mask set if you want transparent regions to show through.
*
1999-11-04 21:52:08 +00:00
* For an explanation of dither offsets, see the GdkRGB documentation. In
* brief, the dither offset is important when re-rendering partial regions of an
* image to a rendered version of the full image, or for when the offsets to a
* base position change, as in scrolling. The dither matrix has to be shifted
* for consistent visual results. If you do not have any of these cases, the
* dither offsets can be both zero.
**/
void
gdk_pixbuf_render_to_drawable (GdkPixbuf *pixbuf,
GdkDrawable *drawable,
GdkGC *gc,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
GdkRgbDither dither,
int x_dither, int y_dither)
{
guchar *buf;
int rowstride;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (drawable != NULL);
g_return_if_fail (gc != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
if (width == 0 || height == 0)
return;
/* This will have to be modified once we support other image types.
* Also, GdkRGB does not have gdk_draw_rgb_32_image_dithalign(), so we
* have to pack the buffer first. Sigh.
*/
if (pixbuf->has_alpha)
buf = remove_alpha (pixbuf, src_x, src_y, width, height, &rowstride);
else
{
buf = pixbuf->pixels + src_y * pixbuf->rowstride + src_x * 3;
rowstride = pixbuf->rowstride;
}
gdk_draw_rgb_image_dithalign (drawable, gc,
dest_x, dest_y,
width, height,
dither,
buf, rowstride,
x_dither, y_dither);
if (pixbuf->has_alpha)
g_free (buf);
}
/**
* gdk_pixbuf_render_to_drawable_alpha:
* @pixbuf: A pixbuf.
* @drawable: Destination drawable.
* @src_x: Source X coordinate within pixbuf.
* @src_y: Source Y coordinates within pixbuf.
* @dest_x: Destination X coordinate within drawable.
* @dest_y: Destination Y coordinate within drawable.
* @width: Width of region to render, in pixels.
* @height: Height of region to render, in pixels.
* @alpha_mode: If the image does not have opacity information, this is ignored.
* Otherwise, specifies how to handle transparency when rendering.
* @alpha_threshold: If the image does have opacity information and @alpha_mode
* is GDK_PIXBUF_ALPHA_BILEVEL, specifies the threshold value for opacity
* values.
* @dither: Dithering mode for GdkRGB.
* @x_dither: X offset for dither.
* @y_dither: Y offset for dither.
*
* Renders a rectangular portion of a pixbuf to a drawable. This is done using
* GdkRGB, so the specified drawable must have the GdkRGB visual and colormap.
*
1999-11-04 21:52:08 +00:00
* When used with #GDK_PIXBUF_ALPHA_BILEVEL, this function has to create a bitmap
* out of the thresholded alpha channel of the image and, it has to set this
* bitmap as the clipping mask for the GC used for drawing. This can be a
* significant performance penalty depending on the size and the complexity of
* the alpha channel of the image. If performance is crucial, consider handling
* the alpha channel yourself (possibly by caching it in your application) and
* using gdk_pixbuf_render_to_drawable() or GdkRGB directly instead.
**/
void
gdk_pixbuf_render_to_drawable_alpha (GdkPixbuf *pixbuf,
GdkDrawable *drawable,
int src_x, int src_y,
int dest_x, int dest_y,
int width, int height,
GdkPixbufAlphaMode alpha_mode,
int alpha_threshold,
GdkRgbDither dither,
int x_dither, int y_dither)
{
GdkBitmap *bitmap = NULL;
GdkGC *gc;
g_return_if_fail (pixbuf != NULL);
g_return_if_fail (pixbuf->colorspace == GDK_COLORSPACE_RGB);
g_return_if_fail (pixbuf->n_channels == 3 || pixbuf->n_channels == 4);
g_return_if_fail (pixbuf->bits_per_sample == 8);
g_return_if_fail (drawable != NULL);
g_return_if_fail (width >= 0 && height >= 0);
g_return_if_fail (src_x >= 0 && src_x + width <= pixbuf->width);
g_return_if_fail (src_y >= 0 && src_y + height <= pixbuf->height);
if (width == 0 || height == 0)
return;
gc = gdk_gc_new (drawable);
if (pixbuf->has_alpha)
{
/* Right now we only support GDK_PIXBUF_ALPHA_BILEVEL, so we
* unconditionally create the clipping mask.
*/
bitmap = gdk_pixmap_new (NULL, width, height, 1);
gdk_pixbuf_render_threshold_alpha (pixbuf, bitmap,
src_x, src_y,
0, 0,
width, height,
alpha_threshold);
gdk_gc_set_clip_mask (gc, bitmap);
gdk_gc_set_clip_origin (gc, dest_x, dest_y);
}
gdk_pixbuf_render_to_drawable (pixbuf, drawable, gc,
src_x, src_y,
dest_x, dest_y,
width, height,
dither,
x_dither, y_dither);
if (bitmap)
gdk_bitmap_unref (bitmap);
gdk_gc_unref (gc);
}
/**
* gdk_pixbuf_render_pixmap_and_mask:
Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) 2000-04-11 Federico Mena Quintero <federico@helixcode.com> Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) to make GdkPixbuf's structures opaque and to remove the libart dependency. * gdk-pixbuf/gdk-pixbuf.h: Removed the public structures. (GdkColorspace): New enum that for now only contains GDK_COLORSPACE_RGB. (GdkPixbufDestroyNotify): New type for the pixbuf's pixels destroy notification function. (GdkInterpType): New num with interpolation types. * *.[ch]: Replace the libart stuff with our own stuff. * pixops/*.[ch]: Likewise. * gdk-pixbuf/gdk-pixbuf-private.h: New file with the private declarations of the GdkPixbuf structures. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_new_from_art_pixbuf): Removed function. (gdk_pixbuf_get_format): Constify. (gdk_pixbuf_get_n_channels): Constify. (gdk_pixbuf_get_has_alpha): Constify. (gdk_pixbuf_get_bits_per_sample): Constify. (gdk_pixbuf_get_pixels): Constify. (gdk_pixbuf_get_width): Constify. (gdk_pixbuf_get_height): Constify. (gdk_pixbuf_get_rowstride): Constify. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_copy): New function to copy a pixbuf. * gdk-pixbuf/gdk-pixbuf-data.c (gdk_pixbuf_new_from_data): Added a bits_per_sample argument; currently only 8 bits per sample are supported. * gdk-pixbuf/gdk-pixbuf-animation.c (gdk_pixbuf_frame_get_pixbuf): New accessor. (gdk_pixbuf_frame_get_x_offset): New accessor. (gdk_pixbuf_frame_get_y_offset): New accessor. (gdk_pixbuf_frame_get_delay_time): New accessor. (gdk_pixbuf_frame_get_action): New accessor. * gdk-pixbuf/gdk-pixbuf-render.c (gdk_pixbuf_render_pixmap_and_mask): Instead of returning a solid mask rectangle for pixbufs without an alpha channel, set the *mask_return to NULL. * gdk-pixbuf/gdk-pixbuf-util.c (gdk_pixbuf_add_alpha): Constify. * gdk-pixbuf/gdk-pixbuf-scale.c: Fix includes. * gdk-pixbuf/gdk-pixbuf-scale.c (gdk_pixbuf_scale): Added some preconditions. Maybe we should also check for the colorspace, bits per pixel, and such. (gdk_pixbuf_composite): Likewise. (gdk_pixbuf_composite_color): Likewise. (gdk_pixbuf_scale_simple): Likewise, and fail gracefully if we cannot allocate the new pixbuf. (gdk_pixbuf_composite_color_simple): Likewise. * gdk-pixbuf/gnome-canvas-pixbuf.c (gnome_canvas_pixbuf_render): Use art_rgb_rgba_affine() or art_rgb_affine() since we no longer have an ArtPixBuf. * gdk-pixbuf/io-bmp.c: Fix includes. * gdk-pixbuf/pixops/pixops.c (pixops_scale_nearest): Fixed cast in an lvalue. * TODO: Populated. * configure.in: Removed checks for libart. * gdk-pixbuf/Makefile.am: Removed references to libart. (noinst_HEADERS): Added gdk-pixbuf-private.h. * gdk-pixbuf/Makefile.am (libgdk_pixbuf_la_LDFLAGS): Incremented the version number of the libtool library to indicate that this definitely is not compatible with the old usage. I know you love me. I know you do. * configure.in: Bumped version number to 0.7.0. * README: Updated. * gdk-pixbuf-config.in (--libs): We no longer require libart. * DEPENDS.libgdk_pixbuf: We no longer depend on libart. * gdk-pixbuf.spec.in: Updated, but I don't guarantee anything.
2000-04-11 07:03:25 +00:00
* @pixbuf: A pixbuf.
* @pixmap_return: Return value for the created pixmap.
* @mask_return: Return value for the created mask.
* @alpha_threshold: Threshold value for opacity values.
*
* Creates a pixmap and a mask bitmap which are returned in the @pixmap_return
* and @mask_return arguments, respectively, and renders a pixbuf and its
* corresponding tresholded alpha mask to them. This is merely a convenience
* function; applications that need to render pixbufs with dither offsets or to
* given drawables should use gdk_pixbuf_render_to_drawable_alpha() or
* gdk_pixbuf_render_to_drawable(), and gdk_pixbuf_render_threshold_alpha().
Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) 2000-04-11 Federico Mena Quintero <federico@helixcode.com> Most of this patch is based on a patch by Havoc Pennington (hp@redhat.com) to make GdkPixbuf's structures opaque and to remove the libart dependency. * gdk-pixbuf/gdk-pixbuf.h: Removed the public structures. (GdkColorspace): New enum that for now only contains GDK_COLORSPACE_RGB. (GdkPixbufDestroyNotify): New type for the pixbuf's pixels destroy notification function. (GdkInterpType): New num with interpolation types. * *.[ch]: Replace the libart stuff with our own stuff. * pixops/*.[ch]: Likewise. * gdk-pixbuf/gdk-pixbuf-private.h: New file with the private declarations of the GdkPixbuf structures. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_new_from_art_pixbuf): Removed function. (gdk_pixbuf_get_format): Constify. (gdk_pixbuf_get_n_channels): Constify. (gdk_pixbuf_get_has_alpha): Constify. (gdk_pixbuf_get_bits_per_sample): Constify. (gdk_pixbuf_get_pixels): Constify. (gdk_pixbuf_get_width): Constify. (gdk_pixbuf_get_height): Constify. (gdk_pixbuf_get_rowstride): Constify. * gdk-pixbuf/gdk-pixbuf.c (gdk_pixbuf_copy): New function to copy a pixbuf. * gdk-pixbuf/gdk-pixbuf-data.c (gdk_pixbuf_new_from_data): Added a bits_per_sample argument; currently only 8 bits per sample are supported. * gdk-pixbuf/gdk-pixbuf-animation.c (gdk_pixbuf_frame_get_pixbuf): New accessor. (gdk_pixbuf_frame_get_x_offset): New accessor. (gdk_pixbuf_frame_get_y_offset): New accessor. (gdk_pixbuf_frame_get_delay_time): New accessor. (gdk_pixbuf_frame_get_action): New accessor. * gdk-pixbuf/gdk-pixbuf-render.c (gdk_pixbuf_render_pixmap_and_mask): Instead of returning a solid mask rectangle for pixbufs without an alpha channel, set the *mask_return to NULL. * gdk-pixbuf/gdk-pixbuf-util.c (gdk_pixbuf_add_alpha): Constify. * gdk-pixbuf/gdk-pixbuf-scale.c: Fix includes. * gdk-pixbuf/gdk-pixbuf-scale.c (gdk_pixbuf_scale): Added some preconditions. Maybe we should also check for the colorspace, bits per pixel, and such. (gdk_pixbuf_composite): Likewise. (gdk_pixbuf_composite_color): Likewise. (gdk_pixbuf_scale_simple): Likewise, and fail gracefully if we cannot allocate the new pixbuf. (gdk_pixbuf_composite_color_simple): Likewise. * gdk-pixbuf/gnome-canvas-pixbuf.c (gnome_canvas_pixbuf_render): Use art_rgb_rgba_affine() or art_rgb_affine() since we no longer have an ArtPixBuf. * gdk-pixbuf/io-bmp.c: Fix includes. * gdk-pixbuf/pixops/pixops.c (pixops_scale_nearest): Fixed cast in an lvalue. * TODO: Populated. * configure.in: Removed checks for libart. * gdk-pixbuf/Makefile.am: Removed references to libart. (noinst_HEADERS): Added gdk-pixbuf-private.h. * gdk-pixbuf/Makefile.am (libgdk_pixbuf_la_LDFLAGS): Incremented the version number of the libtool library to indicate that this definitely is not compatible with the old usage. I know you love me. I know you do. * configure.in: Bumped version number to 0.7.0. * README: Updated. * gdk-pixbuf-config.in (--libs): We no longer require libart. * DEPENDS.libgdk_pixbuf: We no longer depend on libart. * gdk-pixbuf.spec.in: Updated, but I don't guarantee anything.
2000-04-11 07:03:25 +00:00
*
* If the pixbuf does not have an alpha channel, then *@mask_return will be set
* to NULL.
**/
void
gdk_pixbuf_render_pixmap_and_mask (GdkPixbuf *pixbuf,
GdkPixmap **pixmap_return,
GdkBitmap **mask_return,
int alpha_threshold)
{
g_return_if_fail (pixbuf != NULL);
if (pixmap_return)
{
GdkGC *gc;
*pixmap_return = gdk_pixmap_new (NULL, pixbuf->width, pixbuf->height,
gdk_rgb_get_visual ()->depth);
gc = gdk_gc_new (*pixmap_return);
gdk_pixbuf_render_to_drawable (pixbuf, *pixmap_return, gc,
0, 0, 0, 0,
pixbuf->width, pixbuf->height,
GDK_RGB_DITHER_NORMAL,
0, 0);
gdk_gc_unref (gc);
}
if (mask_return)
{
if (pixbuf->has_alpha)
{
*mask_return = gdk_pixmap_new (NULL, pixbuf->width, pixbuf->height, 1);
gdk_pixbuf_render_threshold_alpha (pixbuf, *mask_return,
0, 0, 0, 0,
pixbuf->width, pixbuf->height,
alpha_threshold);
}
else
*mask_return = NULL;
}
}