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https://gitlab.freedesktop.org/cairo/cairo.git
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a6d9b6a671
Propagate the unsigned char* change down the stack. Add cast since XImage uses char* rather than unsigned char*. Fix memory leak of image data. Switch to use cairo_surface_write_png rather than a custom write_png_argb32. Add test to exercise the cairo_image_surface_create_for_png function.
75 lines
2.4 KiB
C
75 lines
2.4 KiB
C
/* imagediff - Compare two images
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*
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* Copyright © 2004 Richard D. Worth
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*
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* Permission to use, copy, modify, distribute, and sell this software
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* and its documentation for any purpose is hereby granted without
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* fee, provided that the above copyright notice appear in all copies
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* and that both that copyright notice and this permission notice
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* appear in supporting documentation, and that the name of Richard Worth
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* not be used in advertising or publicity pertaining to distribution
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* of the software without specific, written prior permission.
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* Richard Worth makes no representations about the suitability of this
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* software for any purpose. It is provided "as is" without express
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* or implied warranty.
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*
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* RICHARD WORTH DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
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* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
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* NO EVENT SHALL RICHARD WORTH BE LIABLE FOR ANY SPECIAL, INDIRECT OR
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* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
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* OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
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* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* Author: Richard D. Worth <richard@theworths.org> */
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#include "buffer-diff.h"
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/* Image comparison code courttesy of Richard Worth.
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* Returns number of pixels changed.
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* Also fills out a "diff" image intended to visually show where the
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* images differ.
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*/
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int
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buffer_diff (unsigned char *buf_a,
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unsigned char *buf_b,
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unsigned char *buf_diff,
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int width, int height, int stride)
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{
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int x, y;
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int total_pixels_changed = 0;
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unsigned char *row_a, *row_b, *row;
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for (y = 0; y < height; y++)
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{
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row_a = buf_a + y * stride;
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row_b = buf_b + y * stride;
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row = buf_diff + y * stride;
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for (x = 0; x < width; x++)
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{
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int channel;
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unsigned char value_a, value_b;
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int pixel_changed = 0;
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for (channel = 0; channel < 4; channel++)
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{
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double diff;
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value_a = row_a[x * 4 + channel];
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value_b = row_b[x * 4 + channel];
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if (value_a != value_b)
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pixel_changed = 1;
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diff = value_a - value_b;
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row[x * 4 + channel] = 128 + diff / 3.0;
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}
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if (pixel_changed) {
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total_pixels_changed++;
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} else {
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row[x*4+0] = 0;
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row[x*4+1] = 0;
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row[x*4+2] = 0;
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}
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row[x * 4 + 3] = 0xff; /* Set ALPHA to 100% (opaque) */
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}
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}
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return total_pixels_changed;
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}
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