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d1834cca19
The interface of the various buffer/image_diff functions is improved to provide the maximum pixel difference in addition to the number of pixels that differ. This value can then be used to compare against a per-backend tolerance. Currently I've set the SVG backend's tolerance to 1 to handle some issues we're currently seeing of single-bit differences on different systems, (but we're not exactly sure why yet). Also I improved the image_diff routines to properly report a status value on failure rather than the bogus value of -1 for pixels_changed.
71 lines
2.4 KiB
C
71 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 <stdio.h>
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#include <stdlib.h>
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#include "buffer-diff.h"
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#include "xmalloc.h"
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int
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main (int argc, char *argv[])
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{
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buffer_diff_result_t result;
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cairo_status_t status;
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unsigned int ax, ay, bx, by;
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if (argc != 3 && argc != 7) {
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fprintf (stderr, "Usage: %s image1.png image2.png [ax ay bx by]\n", argv[0]);
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fprintf (stderr, "Computes an output image designed to present a \"visual diff\" such that even\n");
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fprintf (stderr, "small errors in single pixels are readily apparent in the output.\n");
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fprintf (stderr, "The output image is written on stdout.\n");
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exit (1);
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}
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if (argc == 7) {
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ax = strtoul (argv[3], NULL, 0);
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ay = strtoul (argv[4], NULL, 0);
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bx = strtoul (argv[5], NULL, 0);
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by = strtoul (argv[6], NULL, 0);
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} else {
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ax = ay = bx = by = 0;
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}
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status = image_diff (argv[1], argv[2], NULL, ax, ay, bx, by, &result);
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if (status) {
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fprintf (stderr, "Error comparing images: %s\n",
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cairo_status_to_string (status));
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return 1;
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}
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if (result.pixels_changed)
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fprintf (stderr, "Total pixels changed: %d with a maximum channel difference of %d.\n",
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result.pixels_changed,
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result.max_diff);
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return (result.pixels_changed != 0);
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}
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