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// Copyright (c) 2009 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <math.h>
#include "app/gfx/codec/jpeg_codec.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace gfx {
// out of 100, this indicates how compressed it will be, this should be changed
// with jpeg equality threshold
// static int jpeg_quality = 75; // FIXME(brettw)
static int jpeg_quality = 100;
// The threshold of average color differences where we consider two images
// equal. This number was picked to be a little above the observed difference
// using the above quality.
static double jpeg_equality_threshold = 1.0;
// Computes the average difference between each value in a and b. A and b
// should be the same size. Used to see if two images are approximately equal
// in the presence of compression.
static double AveragePixelDelta(const std::vector<unsigned char>& a,
const std::vector<unsigned char>& b) {
// if the sizes are different, say the average difference is the maximum
if (a.size() != b.size())
return 255.0;
if (a.size() == 0)
return 0; // prevent divide by 0 below
double acc = 0.0;
for (size_t i = 0; i < a.size(); i++)
acc += fabs(static_cast<double>(a[i]) - static_cast<double>(b[i]));
return acc / static_cast<double>(a.size());
}
static void MakeRGBImage(int w, int h, std::vector<unsigned char>* dat) {
dat->resize(w * h * 3);
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
unsigned char* org_px = &(*dat)[(y * w + x) * 3];
org_px[0] = x * 3; // r
org_px[1] = x * 3 + 1; // g
org_px[2] = x * 3 + 2; // b
}
}
}
TEST(JPEGCodec, EncodeDecodeRGB) {
int w = 20, h = 20;
// create an image with known values
std::vector<unsigned char> original;
MakeRGBImage(w, h, &original);
// encode, making sure it was compressed some
std::vector<unsigned char> encoded;
EXPECT_TRUE(JPEGCodec::Encode(&original[0], JPEGCodec::FORMAT_RGB, w, h,
w * 3, jpeg_quality, &encoded));
EXPECT_GT(original.size(), encoded.size());
// decode, it should have the same size as the original
std::vector<unsigned char> decoded;
int outw, outh;
EXPECT_TRUE(JPEGCodec::Decode(&encoded[0], encoded.size(),
JPEGCodec::FORMAT_RGB, &decoded,
&outw, &outh));
ASSERT_EQ(w, outw);
ASSERT_EQ(h, outh);
ASSERT_EQ(original.size(), decoded.size());
// Images must be approximately equal (compression will have introduced some
// minor artifacts).
ASSERT_GE(jpeg_equality_threshold, AveragePixelDelta(original, decoded));
}
TEST(JPEGCodec, EncodeDecodeRGBA) {
int w = 20, h = 20;
// create an image with known values, a must be opaque because it will be
// lost during compression
std::vector<unsigned char> original;
original.resize(w * h * 4);
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
unsigned char* org_px = &original[(y * w + x) * 4];
org_px[0] = x * 3; // r
org_px[1] = x * 3 + 1; // g
org_px[2] = x * 3 + 2; // b
org_px[3] = 0xFF; // a (opaque)
}
}
// encode, making sure it was compressed some
std::vector<unsigned char> encoded;
EXPECT_TRUE(JPEGCodec::Encode(&original[0], JPEGCodec::FORMAT_RGBA, w, h,
w * 4, jpeg_quality, &encoded));
EXPECT_GT(original.size(), encoded.size());
// decode, it should have the same size as the original
std::vector<unsigned char> decoded;
int outw, outh;
EXPECT_TRUE(JPEGCodec::Decode(&encoded[0], encoded.size(),
JPEGCodec::FORMAT_RGBA, &decoded,
&outw, &outh));
ASSERT_EQ(w, outw);
ASSERT_EQ(h, outh);
ASSERT_EQ(original.size(), decoded.size());
// Images must be approximately equal (compression will have introduced some
// minor artifacts).
ASSERT_GE(jpeg_equality_threshold, AveragePixelDelta(original, decoded));
}
// Test that corrupted data decompression causes failures.
TEST(JPEGCodec, DecodeCorrupted) {
int w = 20, h = 20;
// some random data (an uncompressed image)
std::vector<unsigned char> original;
MakeRGBImage(w, h, &original);
// it should fail when given non-JPEG compressed data
std::vector<unsigned char> output;
int outw, outh;
ASSERT_FALSE(JPEGCodec::Decode(&original[0], original.size(),
JPEGCodec::FORMAT_RGB, &output,
&outw, &outh));
// make some compressed data
std::vector<unsigned char> compressed;
ASSERT_TRUE(JPEGCodec::Encode(&original[0], JPEGCodec::FORMAT_RGB, w, h,
w * 3, jpeg_quality, &compressed));
// try decompressing a truncated version
ASSERT_FALSE(JPEGCodec::Decode(&compressed[0], compressed.size() / 2,
JPEGCodec::FORMAT_RGB, &output,
&outw, &outh));
// corrupt it and try decompressing that
for (int i = 10; i < 30; i++)
compressed[i] = i;
ASSERT_FALSE(JPEGCodec::Decode(&compressed[0], compressed.size(),
JPEGCodec::FORMAT_RGB, &output,
&outw, &outh));
}
} // namespace gfx
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