mirror of
https://gitlab.freedesktop.org/cairo/cairo.git
synced 2025-12-20 12:50:10 +01:00
74 lines
2.3 KiB
C
74 lines
2.3 KiB
C
|
/* 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 "buffer_diff.h"
|
||
|
|
|
||
|
|
/* Image comparison code courttesy of Richard Worth.
|
||
|
|
* Returns number of pixels changed.
|
||
|
|
* Also fills out a "diff" image intended to visually show where the
|
||
|
|
* images differ.
|
||
|
|
*/
|
||
|
|
int
|
||
|
|
buffer_diff (char *buf_a, char *buf_b, char *buf_diff,
|
||
|
|
int width, int height, int stride)
|
||
|
|
{
|
||
|
|
int x, y;
|
||
|
|
int total_pixels_changed = 0;
|
||
|
|
unsigned char *row_a, *row_b, *row;
|
||
|
|
|
||
|
|
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_changed = 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_changed = 1;
|
||
|
|
diff = value_a - value_b;
|
||
|
|
row[x * 4 + channel] = 128 + diff / 3.0;
|
||
|
|
}
|
||
|
|
if (pixel_changed) {
|
||
|
|
total_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 total_pixels_changed;
|
||
|
|
}
|