// Copyright (c) 2011 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.
// This file input format is based loosely on
// Tools/DumpRenderTree/ImageDiff.m
// The exact format of this tool's output to stdout is important, to match
// what the run-webkit-tests script expects.
#include <assert.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <algorithm>
#include <iostream>
#include <map>
#include <string>
#include <vector>
#include "../third_party/base/logging.h"
#include "../third_party/base/numerics/safe_conversions.h"
#include "image_diff_png.h"
#if defined(OS_WIN)
#include "windows.h"
#endif
// Return codes used by this utility.
static const int kStatusSame = 0;
static const int kStatusDifferent = 1;
static const int kStatusError = 2;
// Color codes.
static const uint32_t RGBA_RED = 0x000000ff;
static const uint32_t RGBA_ALPHA = 0xff000000;
class Image {
public:
Image() : w_(0), h_(0) {
}
Image(const Image& image)
: w_(image.w_),
h_(image.h_),
data_(image.data_) {
}
bool has_image() const {
return w_ > 0 && h_ > 0;
}
int w() const {
return w_;
}
int h() const {
return h_;
}
const unsigned char* data() const {
return &data_.front();
}
// Creates the image from the given filename on disk, and returns true on
// success.
bool CreateFromFilename(const std::string& path) {
FILE* f = fopen(path.c_str(), "rb");
if (!f)
return false;
std::vector<unsigned char> compressed;
const int buf_size = 1024;
unsigned char buf[buf_size];
size_t num_read = 0;
while ((num_read = fread(buf, 1, buf_size, f)) > 0) {
compressed.insert(compressed.end(), buf, buf + num_read);
}
fclose(f);
if (!image_diff_png::DecodePNG(&compressed[0], compressed.size(),
&data_, &w_, &h_)) {
Clear();
return false;
}
return true;
}
void Clear() {
w_ = h_ = 0;
data_.clear();
}
// Returns the RGBA value of the pixel at the given location
uint32_t pixel_at(int x, int y) const {
if (x >= 0 && x < w_ && y >= 0 && y < h_)
return *reinterpret_cast<const uint32_t*>(&(data_[(y * w_ + x) * 4]));
return 0;
}
void set_pixel_at(int x, int y, uint32_t color) const {
if (x >= 0 && x < w_ && y >= 0 && y < h_) {
void* addr = &const_cast<unsigned char*>(&data_.front())[(y * w_ + x) * 4];
*reinterpret_cast<uint32_t*>(addr) = color;
}
}
private:
// pixel dimensions of the image
int w_, h_;
std::vector<unsigned char> data_;
};
float PercentageDifferent(const Image& baseline, const Image& actual) {
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Compute pixels different in the overlap.
int pixels_different = 0;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
if (baseline.pixel_at(x, y) != actual.pixel_at(x, y))
pixels_different++;
}
}
// Count pixels that are a difference in size as also being different.
int max_w = std::max(baseline.w(), actual.w());
int max_h = std::max(baseline.h(), actual.h());
// These pixels are off the right side, not including the lower right corner.
pixels_different += (max_w - w) * h;
// These pixels are along the bottom, including the lower right corner.
pixels_different += (max_h - h) * max_w;
// Like the WebKit ImageDiff tool, we define percentage different in terms
// of the size of the 'actual' bitmap.
float total_pixels = static_cast<float>(actual.w()) *
static_cast<float>(actual.h());
if (total_pixels == 0) {
// When the bitmap is empty, they are 100% different.
return 100.0f;
}
return 100.0f * pixels_different / total_pixels;
}
// FIXME: Replace with unordered_map when available.
typedef std::map<uint32_t, int32_t> RgbaToCountMap;
float HistogramPercentageDifferent(const Image& baseline, const Image& actual) {
// TODO(johnme): Consider using a joint histogram instead, as described in
// "Comparing Images Using Joint Histograms" by Pass & Zabih
// http://www.cs.cornell.edu/~rdz/papers/pz-jms99.pdf
int w = std::min(baseline.w(), actual.w());
int h = std::min(baseline.h(), actual.h());
// Count occurences of each RGBA pixel value of baseline in the overlap.
RgbaToCountMap baseline_histogram;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
// hash_map operator[] inserts a 0 (default constructor) if key not found.
baseline_histogram[baseline.pixel_at(x, y)]++;
}
}
// Compute pixels different in the histogram of the overlap.
int pixels_different = 0;
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
uint32_t actual_rgba = actual.pixel_at(x, y);
RgbaToCountMap::iterator it = baseline_histogram.find(actual_rgba);
if (it != baseline_histogram.end() && it->second > 0)
it->second--;
else
pixels_different++;
}
}
// Count pixels that are a difference in size as also being different.
int max_w = std::max(baseline.w(), actual.w());
int max_h = std::max(baseline.h(), actual.h());
// These pixels are off the right side, not including the lower right corner.
pixels_different += (max_w - w) * h;
// These pixels are along the bottom, including the lower right corner.
pixels_different += (max_h - h) * max_w;
// Like the WebKit ImageDiff tool, we define percentage different in terms
// of the size of the 'actual' bitmap.
float total_pixels = static_cast<float>(actual.w()) *
static_cast<float>(actual.h());
if (total_pixels == 0) {
// When the bitmap is empty, they are 100% different.
return 100.0f;
}
return 100.0f * pixels_different / total_pixels;
}
void PrintHelp() {
fprintf(stderr,
"Usage:\n"
" image_diff [--histogram] <compare file> <reference file>\n"
" Compares two files on disk, returning 0 when they are the same;\n"
" passing \"--histogram\" additionally calculates a diff of the\n"
" RGBA value histograms (which is resistant to shifts in layout)\n"
" image_diff --diff <compare file> <reference file> <output file>\n"
" Compares two files on disk, outputs an image that visualizes the\n"
" difference to <output file>\n");
}
int CompareImages(const std::string& file1,
const std::string& file2,
bool compare_histograms) {
Image actual_image;
Image baseline_image;
if (!actual_image.CreateFromFilename(file1)) {
fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file1.c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file2.c_str());
return kStatusError;
}
if (compare_histograms) {
float percent = HistogramPercentageDifferent(actual_image, baseline_image);
const char* passed = percent > 0.0 ? "failed" : "passed";
printf("histogram diff: %01.2f%% %s\n", percent, passed);
}
const char* diff_name = compare_histograms ? "exact diff" : "diff";
float percent = PercentageDifferent(actual_image, baseline_image);
const char* passed = percent > 0.0 ? "failed" : "passed";
printf("%s: %01.2f%% %s\n", diff_name, percent, passed);
if (percent > 0.0) {
// failure: The WebKit version also writes the difference image to
// stdout, which seems excessive for our needs.
return kStatusDifferent;
}
// success
return kStatusSame;
/* Untested mode that acts like WebKit's image comparator. I wrote this but
decided it's too complicated. We may use it in the future if it looks useful
char buffer[2048];
while (fgets(buffer, sizeof(buffer), stdin)) {
if (strncmp("Content-length: ", buffer, 16) == 0) {
char* context;
strtok_s(buffer, " ", &context);
int image_size = strtol(strtok_s(NULL, " ", &context), NULL, 10);
bool success = false;
if (image_size > 0 && actual_image.has_image() == 0) {
if (!actual_image.CreateFromStdin(image_size)) {
fputs("Error, input image can't be decoded.\n", stderr);
return 1;
}
} else if (image_size > 0 && baseline_image.has_image() == 0) {
if (!baseline_image.CreateFromStdin(image_size)) {
fputs("Error, baseline image can't be decoded.\n", stderr);
return 1;
}
} else {
fputs("Error, image size must be specified.\n", stderr);
return 1;
}
}
if (actual_image.has_image() && baseline_image.has_image()) {
float percent = PercentageDifferent(actual_image, baseline_image);
if (percent > 0.0) {
// failure: The WebKit version also writes the difference image to
// stdout, which seems excessive for our needs.
printf("diff: %01.2f%% failed\n", percent);
} else {
// success
printf("diff: %01.2f%% passed\n", percent);
}
actual_image.Clear();
baseline_image.Clear();
}
fflush(stdout);
}
*/
}
bool CreateImageDiff(const Image& image1, const Image& image2, Image* out) {
int w = std::min(image1.w(), image2.w());
int h = std::min(image1.h(), image2.h());
*out = Image(image1);
bool same = (image1.w() == image2.w()) && (image1.h() == image2.h());
// TODO(estade): do something with the extra pixels if the image sizes
// are different.
for (int y = 0; y < h; y++) {
for (int x = 0; x < w; x++) {
uint32_t base_pixel = image1.pixel_at(x, y);
if (base_pixel != image2.pixel_at(x, y)) {
// Set differing pixels red.
out->set_pixel_at(x, y, RGBA_RED | RGBA_ALPHA);
same = false;
} else {
// Set same pixels as faded.
uint32_t alpha = base_pixel & RGBA_ALPHA;
uint32_t new_pixel = base_pixel - ((alpha / 2) & RGBA_ALPHA);
out->set_pixel_at(x, y, new_pixel);
}
}
}
return same;
}
int DiffImages(const std::string& file1,
const std::string& file2,
const std::string& out_file) {
Image actual_image;
Image baseline_image;
if (!actual_image.CreateFromFilename(file1)) {
fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file1.c_str());
return kStatusError;
}
if (!baseline_image.CreateFromFilename(file2)) {
fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file2.c_str());
return kStatusError;
}
Image diff_image;
bool same = CreateImageDiff(baseline_image, actual_image, &diff_image);
if (same)
return kStatusSame;
std::vector<unsigned char> png_encoding;
image_diff_png::EncodeRGBAPNG(
diff_image.data(), diff_image.w(), diff_image.h(),
diff_image.w() * 4, &png_encoding);
FILE *f = fopen(out_file.c_str(), "wb");
if (!f)
return kStatusError;
size_t size = png_encoding.size();
char *ptr = reinterpret_cast<char*>(&png_encoding.front());
if (fwrite(ptr, 1, size, f) != size)
return kStatusError;
return kStatusDifferent;
}
int main(int argc, const char* argv[]) {
bool histograms = false;
bool produce_diff_image = false;
std::string filename1;
std::string filename2;
std::string diff_filename;
int i;
for (i = 1; i < argc; ++i) {
const char* arg = argv[i];
if (strstr(arg, "--") != arg)
break;
if (strcmp(arg, "--histogram") == 0) {
histograms = true;
} else if (strcmp(arg, "--diff") == 0) {
produce_diff_image = true;
}
}
if (i < argc) {
filename1 = argv[i];
++i;
}
if (i < argc) {
filename2 = argv[i];
++i;
}
if (i < argc) {
diff_filename = argv[i];
++i;
}
if (produce_diff_image) {
if (!diff_filename.empty()) {
return DiffImages(filename1, filename2, diff_filename);
}
} else if (!filename2.empty()) {
return CompareImages(filename1, filename2, histograms);
}
PrintHelp();
return kStatusError;
}