136 lines
4.2 KiB
C
136 lines
4.2 KiB
C
/*
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* Copyright (C) 2011,2021 Red Hat Inc.
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*
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* Author:
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* Benjamin Otte <otte@gnome.org>
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Library General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Library General Public License for more details.
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*
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* You should have received a copy of the GNU Library General Public
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* License along with this library. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include "config.h"
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#include "reftest-compare.h"
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/* Compares two GDK_MEMORY_DEFAULT buffers, returning NULL if the
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* buffers are equal or a surface containing a diff between the two
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* surfaces.
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*
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* This function is originally from cairo:test/buffer-diff.c.
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* Copyright © 2004 Richard D. Worth
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*/
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static GdkTexture *
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buffer_diff_core (const guchar *buf_a,
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int stride_a,
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const guchar *buf_b,
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int stride_b,
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int width,
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int height)
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{
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int x, y;
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guchar *buf_diff = NULL;
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int stride_diff = 0;
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GdkTexture *diff = NULL;
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for (y = 0; y < height; y++)
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{
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const guint32 *row_a = (const guint32 *) (buf_a + y * stride_a);
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const guint32 *row_b = (const guint32 *) (buf_b + y * stride_b);
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guint32 *row = (guint32 *) (buf_diff + y * stride_diff);
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for (x = 0; x < width; x++)
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{
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int channel;
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guint32 diff_pixel = 0;
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/* check if the pixels are the same */
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if (row_a[x] == row_b[x])
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continue;
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/* even if they're not literally the same, fully-transparent
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* pixels are effectively the same regardless of colour */
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if ((row_a[x] & 0xff000000) == 0 && (row_b[x] & 0xff000000) == 0)
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continue;
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if (diff == NULL)
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{
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GBytes *bytes;
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stride_diff = 4 * width;
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buf_diff = g_malloc0_n (stride_diff, height);
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bytes = g_bytes_new_take (buf_diff, stride_diff * height);
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diff = gdk_memory_texture_new (width, height,
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GDK_MEMORY_DEFAULT,
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bytes,
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stride_diff);
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row = (guint32 *) (buf_diff + y * stride_diff);
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}
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/* calculate a difference value for all 4 channels */
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for (channel = 0; channel < 4; channel++)
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{
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int value_a = (row_a[x] >> (channel*8)) & 0xff;
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int value_b = (row_b[x] >> (channel*8)) & 0xff;
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guint channel_diff;
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channel_diff = ABS (value_a - value_b);
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channel_diff *= 4; /* emphasize */
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if (channel_diff)
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channel_diff += 128; /* make sure it's visible */
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if (channel_diff > 255)
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channel_diff = 255;
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diff_pixel |= channel_diff << (channel * 8);
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}
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if ((diff_pixel & 0x00ffffff) == 0)
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{
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/* alpha only difference, convert to luminance */
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guint8 alpha = diff_pixel >> 24;
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diff_pixel = alpha * 0x010101;
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}
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/* make the pixel fully opaque */
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diff_pixel |= 0xff000000;
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row[x] = diff_pixel;
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}
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}
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return diff;
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}
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GdkTexture *
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reftest_compare_textures (GdkTexture *texture1,
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GdkTexture *texture2)
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{
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int w, h;
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guchar *data1, *data2;
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GdkTexture *diff;
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w = MAX (gdk_texture_get_width (texture1), gdk_texture_get_width (texture2));
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h = MAX (gdk_texture_get_height (texture1), gdk_texture_get_height (texture2));
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data1 = g_malloc_n (w * 4, h);
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gdk_texture_download (texture1, data1, w * 4);
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data2 = g_malloc_n (w * 4, h);
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gdk_texture_download (texture2, data2, w * 4);
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diff = buffer_diff_core (data1, w * 4,
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data2, w * 4,
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w, h);
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g_free (data1);
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g_free (data2);
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return diff;
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}
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