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/* imagediff - Compare two images
*
* Copyright © 2004 Richard D. Worth
*
* Permission to use, copy, modify, distribute, and sell this software
* and its documentation for any purpose is hereby granted without
* fee, provided that the above copyright notice appear in all copies
* and that both that copyright notice and this permission notice
* appear in supporting documentation, and that the name of Richard Worth
* not be used in advertising or publicity pertaining to distribution
* of the software without specific, written prior permission.
* Richard Worth makes no representations about the suitability of this
* software for any purpose. It is provided "as is" without express
* or implied warranty.
*
* RICHARD WORTH DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
* INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN
* NO EVENT SHALL RICHARD WORTH BE LIABLE FOR ANY SPECIAL, INDIRECT OR
* CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS
* OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT,
* NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
* Author: Richard D. Worth <richard@theworths.org> */
#include <stdio.h>
#include <unistd.h>
#include <errno.h>
#include <string.h>
#include "cairo-test.h"
#include "buffer-diff.h"
#include "read-png.h"
#include "write-png.h"
#include "xmalloc.h"
static void
xunlink (const char *pathname)
{
if (unlink (pathname) < 0 && errno != ENOENT) {
cairo_test_log (" Error: Cannot remove %s: %s\n",
pathname, strerror (errno));
exit (1);
}
}
int
buffer_diff (unsigned char *buf_a,
unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride)
{
int x, y;
unsigned char *row_a, *row_b, *row;
int pixels_changed = 0;
for (y = 0; y < height; y++)
{
row_a = buf_a + y * stride;
row_b = buf_b + y * stride;
row = buf_diff + y * stride;
for (x = 0; x < width; x++)
{
int channel;
unsigned char value_a, value_b;
int pixel_differs = 0;
for (channel = 0; channel < 4; channel++)
{
double diff;
value_a = row_a[x * 4 + channel];
value_b = row_b[x * 4 + channel];
if (value_a != value_b)
pixel_differs = 1;
diff = value_a - value_b;
row[x * 4 + channel] = 128 + diff / 3.0;
}
if (pixel_differs) {
pixels_changed++;
} else {
row[x*4+0] = 0;
row[x*4+1] = 0;
row[x*4+2] = 0;
}
row[x * 4 + 3] = 0xff; /* Set ALPHA to 100% (opaque) */
}
}
return pixels_changed;
}
/* Image comparison code courtesy of Richard Worth <richard@theworths.org>
* Returns number of pixels changed, (or -1 on error).
* Also saves a "diff" image intended to visually show where the
* images differ.
*/
int
image_diff (const char *filename_a,
const char *filename_b,
const char *filename_diff)
{
int pixels_changed;
unsigned int width_a, height_a, stride_a;
unsigned int width_b, height_b, stride_b;
unsigned char *buf_a, *buf_b, *buf_diff;
read_png_status_t status;
status = read_png_argb32 (filename_a, &buf_a, &width_a, &height_a, &stride_a);
if (status)
return -1;
status = read_png_argb32 (filename_b, &buf_b, &width_b, &height_b, &stride_b);
if (status)
return -1;
if (width_a != width_b ||
height_a != height_b ||
stride_a != stride_b)
{
cairo_test_log ("Error: Image size mismatch: (%dx%d@%d) vs. (%dx%d@%d)\n"
" for %s vs. %s\n",
width_a, height_a, stride_a,
width_b, height_b, stride_b,
filename_a, filename_b);
free (buf_a);
free (buf_b);
return -1;
}
buf_diff = xcalloc (stride_a * height_a, 1);
pixels_changed = buffer_diff (buf_a, buf_b, buf_diff,
width_a, height_a, stride_a);
if (pixels_changed) {
FILE *png_file = fopen (filename_diff, "wb");
write_png_argb32 (buf_diff, png_file, width_a, height_a, stride_a);
fclose (png_file);
} else {
xunlink (filename_diff);
}
free (buf_a);
free (buf_b);
free (buf_diff);
return pixels_changed;
}
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