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rewrite buffer_diff to be endian safe and add a new fuction buffer_diff_noalpha

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This commit is contained in:
Jeff Muizelaar 2005-08-05 11:15:04 +00:00
parent 2e1eaa88ff
commit 5f78feda5d
3 changed files with 77 additions and 27 deletions
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7
ChangeLog
View file

@ -1,3 +1,10 @@
2005-08-05 Jeff Muizelaar <jeff@infidigm.net>
* test/buffer-diff.c: (buffer_diff_core), (buffer_diff),
(buffer_diff_noalpha):
* test/buffer-diff.h: rewrite buffer_diff to be endian safe
and add a new fuction buffer_diff_noalpha
2005-08-05 Carl Worth <cworth@cworth.org>
* doc/public/cairo-sections.txt: Remove CAIRO_BEGIN_DECLS and

83
test/buffer-diff.c
View file

@ -33,6 +33,7 @@
#endif
#include <errno.h>
#include <string.h>
#include <pixman.h>
#include "cairo-test.h"
@ -51,18 +52,27 @@ xunlink (const char *pathname)
}
}
int
buffer_diff (unsigned char *buf_a,
unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride)
/* This function should be rewritten to compare all formats supported by
* cairo_format_t instead of taking a mask as a parameter.
*/
static int
buffer_diff_core (unsigned char *_buf_a,
unsigned char *_buf_b,
unsigned char *_buf_diff,
int width,
int height,
int stride,
pixman_bits_t mask)
{
int x, y;
unsigned char *row_a, *row_b, *row;
pixman_bits_t *row_a, *row_b, *row;
int pixels_changed = 0;
pixman_bits_t *buf_a = (pixman_bits_t*)_buf_a;
pixman_bits_t *buf_b = (pixman_bits_t*)_buf_b;
pixman_bits_t *buf_diff = (pixman_bits_t*)_buf_diff;
stride /= sizeof(pixman_bits_t);
for (y = 0; y < height; y++)
{
row_a = buf_a + y * stride;
@ -70,33 +80,54 @@ buffer_diff (unsigned char *buf_a,
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) {
/* check if the pixels are the same */
if ((row_a[x] & mask) != (row_b[x] & mask)) {
int channel;
pixman_bits_t diff_pixel = 0;
/* calculate a difference value for all 4 channels */
for (channel = 0; channel < 4; channel++) {
unsigned char value_a = (row_a[x] >> (channel*8));
unsigned char value_b = (row_b[x] >> (channel*8));
double diff;
diff = value_a - value_b;
diff_pixel |= (unsigned char)(128 + diff / 3.0) << (channel*8);
}
pixels_changed++;
row[x] = diff_pixel;
} else {
row[x*4+0] = 0;
row[x*4+1] = 0;
row[x*4+2] = 0;
row[x] = 0;
}
row[x * 4 + 3] = 0xff; /* Set ALPHA to 100% (opaque) */
row[x] |= 0xff000000; /* Set ALPHA to 100% (opaque) */
}
}
return pixels_changed;
}
int
buffer_diff (unsigned char *buf_a,
unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride)
{
return buffer_diff_core(buf_a, buf_b, buf_diff, width, height, stride, 0xffffffff);
}
int
buffer_diff_noalpha (unsigned char *buf_a,
unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride)
{
return buffer_diff_core(buf_a, buf_b, buf_diff, width, height, stride, 0x00ffffff);
}
/* 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

14
test/buffer-diff.h
View file

@ -26,7 +26,7 @@
#ifndef BUFFER_DIFF_H
#define BUFFER_DIFF_H
/* Returns number of pixels changed, (or -1 on error).
/* Returns number of pixels changed.
* Also fills in a "diff" buffer intended to visually show where the
* images differ.
*/
@ -38,6 +38,18 @@ buffer_diff (unsigned char *buf_a,
int height,
int stride);
/* Returns number of pixels changed ignoring the alpha channel.
* Also fills in a "diff" buffer intended to visually show where the
* images differ.
*/
int
buffer_diff_noalpha (unsigned char *buf_a,
unsigned char *buf_b,
unsigned char *buf_diff,
int width,
int height,
int stride);
/* Returns number of pixels changed, (or -1 on error).
* Also saves a "diff" image intended to visually show where the
* images differ.