summaryrefslogtreecommitdiff
path: root/test/buffer-diff.c
blob: f37ef6e4054805da24b5844f6e0cb4d5d297ce5c (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
/* 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"
#include "xmalloc.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++;
		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;
}