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+// 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 <stdio.h>
+#include <string.h>
+
+#include <algorithm>
+#include <cstdint>
+#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;
+}
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