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PlatformImage.cpp
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99 lines (85 loc) · 3.95 KB
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/*
* Copyright (C) 2005, 2007, 2015 Apple Inc. All rights reserved.
* Copyright (C) 2005 Ben La Monica <ben.lamonica@gmail.com>. All rights reserved.
* Copyright (C) 2011 Brent Fulgham. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY
* EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR
* CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
* PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
* OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*/
#include "PlatformImage.h"
#include <algorithm>
#include <cstdlib>
namespace ImageDiff {
bool PlatformImage::isCompatible(const PlatformImage& other) const
{
return width() == other.width()
&& height() == other.height()
&& rowBytes() == other.rowBytes()
&& hasAlpha() == other.hasAlpha();
}
std::unique_ptr<PlatformImage> PlatformImage::difference(const PlatformImage& other, float& percentageDifference)
{
size_t width = this->width();
size_t height = this->height();
// Compare the content of the 2 bitmaps
void* diffBuffer = malloc(width * height);
float count = 0.0f;
float sum = 0.0f;
float maxDistance = 0.0f;
unsigned char* basePixel = this->pixels();
unsigned char* pixel = other.pixels();
unsigned char* diffPixel = reinterpret_cast<unsigned char*>(diffBuffer);
for (size_t y = 0; y < height; ++y) {
for (size_t x = 0; x < width; ++x) {
float red = (pixel[0] - basePixel[0]) / std::max<float>(255 - basePixel[0], basePixel[0]);
float green = (pixel[1] - basePixel[1]) / std::max<float>(255 - basePixel[1], basePixel[1]);
float blue = (pixel[2] - basePixel[2]) / std::max<float>(255 - basePixel[2], basePixel[2]);
float alpha = (pixel[3] - basePixel[3]) / std::max<float>(255 - basePixel[3], basePixel[3]);
float distance = sqrtf(red * red + green * green + blue * blue + alpha * alpha) / 2.0f;
*diffPixel++ = static_cast<unsigned char>(distance * 255.0f);
if (distance >= 1.0f / 255.0f) {
count += 1.0f;
sum += distance;
if (distance > maxDistance)
maxDistance = distance;
}
basePixel += 4;
pixel += 4;
}
}
// Compute the difference as a percentage combining both the number of different pixels and their difference amount i.e. the average distance over the entire image
if (count > 0.0f)
percentageDifference = 100.0f * sum / (height * width);
else
percentageDifference = 0.0f;
if (!percentageDifference) {
free(diffBuffer);
return nullptr;
}
// Generate a normalized diff image if there is any difference
if (maxDistance < 1.0f) {
diffPixel = reinterpret_cast<unsigned char*>(diffBuffer);
for (size_t p = 0; p < height * width; ++p)
diffPixel[p] /= maxDistance;
}
return PlatformImage::createFromDiffData(diffBuffer, width, height);
}
} // namespace ImageDiff