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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> */
#if HAVE_CONFIG_H
#include "config.h"
#endif
#include <stdio.h>
#include <stdlib.h>
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <errno.h>
#include <string.h>
#include <pixman.h>
#include "cairo-test.h"
#include "pdiff.h"
#include "buffer-diff.h"
/* Don't allow any differences greater than this value, even if pdiff
* claims that the images are identical */
#define PERCEPTUAL_DIFF_THRESHOLD 25
/* Compare two buffers, returning the number of pixels that are
* different and the maximum difference of any single color channel in
* result_ret.
*
* This function should be rewritten to compare all formats supported by
* cairo_format_t instead of taking a mask as a parameter.
*/
static void
buffer_diff_core (const unsigned char *_buf_a, int stride_a,
const unsigned char *_buf_b, int stride_b,
unsigned char *_buf_diff, int stride_diff,
int width,
int height,
uint32_t mask,
buffer_diff_result_t *result_ret)
{
const uint32_t *buf_a = (const uint32_t*) _buf_a;
const uint32_t *buf_b = (const uint32_t*) _buf_b;
uint32_t *buf_diff = (uint32_t*) _buf_diff;
int x, y;
buffer_diff_result_t result = {0, 0};
stride_a /= sizeof (uint32_t);
stride_b /= sizeof (uint32_t);
stride_diff /= sizeof (uint32_t);
for (y = 0; y < height; y++) {
const uint32_t *row_a = buf_a + y * stride_a;
const uint32_t *row_b = buf_b + y * stride_b;
uint32_t *row = buf_diff + y * stride_diff;
for (x = 0; x < width; x++) {
/* check if the pixels are the same */
if ((row_a[x] & mask) != (row_b[x] & mask)) {
int channel;
uint32_t diff_pixel = 0;
/* calculate a difference value for all 4 channels */
for (channel = 0; channel < 4; channel++) {
int value_a = (row_a[x] >> (channel*8)) & 0xff;
int value_b = (row_b[x] >> (channel*8)) & 0xff;
unsigned int diff;
diff = abs (value_a - value_b);
if (diff > result.max_diff)
result.max_diff = diff;
diff *= 4; /* emphasize */
if (diff)
diff += 128; /* make sure it's visible */
if (diff > 255)
diff = 255;
diff_pixel |= diff << (channel*8);
}
result.pixels_changed++;
if ((diff_pixel & 0x00ffffff) == 0) {
/* alpha only difference, convert to luminance */
uint8_t alpha = diff_pixel >> 24;
diff_pixel = alpha * 0x010101;
}
row[x] = diff_pixel;
} else {
row[x] = 0;
}
row[x] |= 0xff000000; /* Set ALPHA to 100% (opaque) */
}
}
*result_ret = result;
}
/* Compares two image surfaces
*
* Provides number of pixels changed and maximum single-channel
* difference in result.
*
* Also fills in a "diff" surface intended to visually show where the
* images differ.
*/
static void
compare_surfaces (const cairo_test_context_t *ctx,
cairo_surface_t *surface_a,
cairo_surface_t *surface_b,
cairo_surface_t *surface_diff,
buffer_diff_result_t *result)
{
/* These default values were taken straight from the
* perceptualdiff program. We'll probably want to tune these as
* necessary. */
double gamma = 2.2;
double luminance = 100.0;
double field_of_view = 45.0;
int discernible_pixels_changed;
/* First, we run cairo's old buffer_diff algorithm which looks for
* pixel-perfect images, (we do this first since the test suite
* runs about 3x slower if we run pdiff_compare first).
*/
buffer_diff_core (cairo_image_surface_get_data (surface_a),
cairo_image_surface_get_stride (surface_a),
cairo_image_surface_get_data (surface_b),
cairo_image_surface_get_stride (surface_b),
cairo_image_surface_get_data (surface_diff),
cairo_image_surface_get_stride (surface_diff),
cairo_image_surface_get_width (surface_a),
cairo_image_surface_get_height (surface_a),
cairo_surface_get_content (surface_a) & CAIRO_CONTENT_ALPHA ? 0xffffffff : 0x00ffffff,
result);
if (result->pixels_changed == 0)
return;
cairo_test_log (ctx,
"%d pixels differ (with maximum difference of %d) from reference image\n",
result->pixels_changed, result->max_diff);
/* Then, if there are any different pixels, we give the pdiff code
* a crack at the images. If it decides that there are no visually
* discernible differences in any pixels, then we accept this
* result as good enough.
*
* Only let pdiff have a crack at the comparison if the max difference
* is lower than a threshold, otherwise some problems could be masked.
*/
if (result->max_diff < PERCEPTUAL_DIFF_THRESHOLD) {
discernible_pixels_changed = pdiff_compare (surface_a, surface_b,
gamma, luminance, field_of_view);
if (discernible_pixels_changed == 0) {
result->pixels_changed = 0;
cairo_test_log (ctx,
"But perceptual diff finds no visually discernible difference.\n"
"Accepting result.\n");
}
}
}
void
buffer_diff_noalpha (const unsigned char *buf_a,
const unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride,
buffer_diff_result_t *result)
{
buffer_diff_core(buf_a, stride,
buf_b, stride,
buf_diff, stride,
width, height,
0x00ffffff,
result);
}
static cairo_bool_t
same_size (cairo_surface_t *a, cairo_surface_t *b)
{
unsigned int width_a, height_a;
unsigned int width_b, height_b;
width_a = cairo_image_surface_get_width (a);
height_a = cairo_image_surface_get_height (a);
width_b = cairo_image_surface_get_width (b);
height_b = cairo_image_surface_get_height (b);
return width_a == width_b && height_a == height_b;
}
/* 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.
*
* The return value simply indicates whether a check was successfully
* made, (as opposed to a file-not-found condition or similar). It
* does not indicate anything about how much the images differ. For
* that, see result.
*
* One failure mode is if the two images provided do not have the same
* dimensions. In this case, this function will return
* CAIRO_STATUS_SURFACE_TYPE_MISMATCH (which is a bit of an abuse, but
* oh well).
*/
cairo_status_t
image_diff (const cairo_test_context_t *ctx,
cairo_surface_t *surface_a,
cairo_surface_t *surface_b,
cairo_surface_t *surface_diff,
buffer_diff_result_t *result)
{
if (cairo_surface_status (surface_a))
return cairo_surface_status (surface_a);
if (cairo_surface_status (surface_b))
return cairo_surface_status (surface_b);
if (cairo_surface_status (surface_diff))
return cairo_surface_status (surface_diff);
if (! same_size (surface_a, surface_b) ||
! same_size (surface_a, surface_diff))
{
cairo_test_log (ctx, "Error: Image size mismatch\n");
return CAIRO_STATUS_SURFACE_TYPE_MISMATCH;
}
compare_surfaces (ctx, surface_a, surface_b, surface_diff, result);
return CAIRO_STATUS_SUCCESS;
}
cairo_bool_t
image_diff_is_failure (const buffer_diff_result_t *result,
unsigned int tolerance)
{
return result->pixels_changed &&
result->max_diff > tolerance;
}