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/*
* Copyright (C) 2010 Igalia S.L.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY APPLE COMPUTER, INC. ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL APPLE COMPUTER, INC. OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "config.h"
#include "GdkCairoUtilities.h"
#include <cairo.h>
#include <gtk/gtk.h>
static inline unsigned char* getCairoSurfacePixel(unsigned char* data, unsigned x, unsigned y, unsigned rowStride)
{
return data + (y * rowStride) + x * 4;
}
static inline guchar* getGdkPixbufPixel(guchar* data, unsigned x, unsigned y, unsigned rowStride)
{
return data + (y * rowStride) + x * 4;
}
GdkPixbuf* cairoImageSurfaceToGdkPixbuf(cairo_surface_t* surface)
{
int width = cairo_image_surface_get_width(surface);
int height = cairo_image_surface_get_height(surface);
unsigned char* surfaceData = cairo_image_surface_get_data(surface);
int surfaceRowStride = cairo_image_surface_get_stride(surface);
GdkPixbuf* dest = gdk_pixbuf_new(GDK_COLORSPACE_RGB, TRUE, 8, width, height);
if (!dest)
return 0;
guchar* pixbufData = gdk_pixbuf_get_pixels(dest);
int pixbufRowStride = gdk_pixbuf_get_rowstride(dest);
/* From: http://cairographics.org/manual/cairo-image-surface.html#cairo-format-t
* "CAIRO_FORMAT_ARGB32: each pixel is a 32-bit quantity, with alpha in
* the upper 8 bits, then red, then green, then blue. The 32-bit
* quantities are stored native-endian. Pre-multiplied alpha is used.
* (That is, 50% transparent red is 0x80800000, not 0x80ff0000.)"
*
* See http://developer.gimp.org/api/2.0/gdk-pixbuf/gdk-pixbuf-gdk-pixbuf.html#GdkPixbuf
* for information on the structure of GdkPixbufs stored with GDK_COLORSPACE_RGB.
*
* RGB color channels in CAIRO_FORMAT_ARGB32 are stored based on the
* endianness of the machine and are also multiplied by the alpha channel.
* To properly transfer the data from the Cairo surface we must divide each
* of the RGB channels by the alpha channel and then reorder all channels
* if this machine is little-endian.
*/
for (int y = 0; y < height; y++) {
for (int x = 0; x < width; x++) {
unsigned char* source = getCairoSurfacePixel(surfaceData, x, y, surfaceRowStride);
guchar* dest = getGdkPixbufPixel(pixbufData, x, y, pixbufRowStride);
#if G_BYTE_ORDER == G_LITTLE_ENDIAN
guchar alpha = source[3];
dest[0] = alpha ? ((source[2] * 255) / alpha) : 0;
dest[1] = alpha ? ((source[1] * 255) / alpha) : 0;
dest[2] = alpha ? ((source[0] * 255) / alpha) : 0;
dest[3] = alpha;
#else
guchar alpha = source[0];
dest[0] = alpha ? ((source[1] * 255) / alpha) : 0;
dest[1] = alpha ? ((source[2] * 255) / alpha) : 0;
dest[2] = alpha ? ((source[3] * 255) / alpha) : 0;
dest[3] = alpha;
#endif
}
}
return dest;
}
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