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/*
* Copyright (C) 2011 Red Hat Inc.
*
* Author:
* Benjamin Otte <otte@gnome.org>
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Library General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Library General Public License for more details.
*
* You should have received a copy of the GNU Library General Public
* License along with this library. If not, see <http://www.gnu.org/licenses/>.
*/
#include "config.h"
#include "reftest-compare.h"
static void
get_surface_size (cairo_surface_t *surface,
int *width,
int *height)
{
GdkRectangle area;
cairo_t *cr;
cr = cairo_create (surface);
if (!gdk_cairo_get_clip_rectangle (cr, &area))
{
g_assert_not_reached ();
}
g_assert (area.x == 0 && area.y == 0);
g_assert (area.width > 0 && area.height > 0);
*width = area.width;
*height = area.height;
}
static cairo_surface_t *
coerce_surface_for_comparison (cairo_surface_t *surface,
int width,
int height)
{
cairo_surface_t *coerced;
cairo_t *cr;
coerced = cairo_image_surface_create (CAIRO_FORMAT_ARGB32,
width,
height);
cr = cairo_create (coerced);
cairo_set_source_surface (cr, surface, 0, 0);
cairo_set_operator (cr, CAIRO_OPERATOR_SOURCE);
cairo_paint (cr);
cairo_destroy (cr);
g_assert (cairo_surface_status (coerced) == CAIRO_STATUS_SUCCESS);
return coerced;
}
/* Compares two CAIRO_FORMAT_ARGB32 buffers, returning NULL if the
* buffers are equal or a surface containing a diff between the two
* surfaces.
*
* This function should be rewritten to compare all formats supported by
* cairo_format_t instead of taking a mask as a parameter.
*
* This function is originally from cairo:test/buffer-diff.c.
* Copyright © 2004 Richard D. Worth
*/
static cairo_surface_t *
buffer_diff_core (const guchar *buf_a,
int stride_a,
const guchar *buf_b,
int stride_b,
int width,
int height)
{
int x, y;
guchar *buf_diff = NULL;
int stride_diff = 0;
cairo_surface_t *diff = NULL;
for (y = 0; y < height; y++)
{
const guint32 *row_a = (const guint32 *) (buf_a + y * stride_a);
const guint32 *row_b = (const guint32 *) (buf_b + y * stride_b);
guint32 *row = (guint32 *) (buf_diff + y * stride_diff);
for (x = 0; x < width; x++)
{
int channel;
guint32 diff_pixel = 0;
/* check if the pixels are the same */
if (row_a[x] == row_b[x])
continue;
if (diff == NULL)
{
diff = cairo_image_surface_create (CAIRO_FORMAT_RGB24,
width,
height);
g_assert (cairo_surface_status (diff) == CAIRO_STATUS_SUCCESS);
buf_diff = cairo_image_surface_get_data (diff);
stride_diff = cairo_image_surface_get_stride (diff);
row = (guint32 *) (buf_diff + y * stride_diff);
}
/* 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;
guint diff;
diff = ABS (value_a - value_b);
diff *= 4; /* emphasize */
if (diff)
diff += 128; /* make sure it's visible */
if (diff > 255)
diff = 255;
diff_pixel |= diff << (channel*8);
}
if ((diff_pixel & 0x00ffffff) == 0)
{
/* alpha only difference, convert to luminance */
guint8 alpha = diff_pixel >> 24;
diff_pixel = alpha * 0x010101;
}
row[x] = diff_pixel;
}
}
return diff;
}
cairo_surface_t *
reftest_compare_surfaces (cairo_surface_t *surface1,
cairo_surface_t *surface2)
{
int w1, h1, w2, h2, w, h;
cairo_surface_t *coerced1, *coerced2, *diff;
get_surface_size (surface1, &w1, &h1);
get_surface_size (surface2, &w2, &h2);
w = MAX (w1, w2);
h = MAX (h1, h2);
coerced1 = coerce_surface_for_comparison (surface1, w, h);
coerced2 = coerce_surface_for_comparison (surface2, w, h);
diff = buffer_diff_core (cairo_image_surface_get_data (coerced1),
cairo_image_surface_get_stride (coerced1),
cairo_image_surface_get_data (coerced2),
cairo_image_surface_get_stride (coerced2),
w, h);
cairo_surface_destroy (coerced1);
cairo_surface_destroy (coerced2);
return diff;
}
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