// 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 "samples/image_diff_png.h" #include "third_party/base/logging.h" #include "third_party/base/numerics/safe_conversions.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 size_t kBufSize = 1024; unsigned char buf[kBufSize]; size_t num_read = 0; while ((num_read = fread(buf, 1, kBufSize, f)) > 0) { compressed.insert(compressed.end(), buf, buf + num_read); } fclose(f); if (!image_diff_png::DecodePNG(compressed.data(), 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 (!pixel_in_bounds(x, y)) return 0; return *reinterpret_cast<const uint32_t*>(&(data_[pixel_address(x, y)])); } void set_pixel_at(int x, int y, uint32_t color) { if (!pixel_in_bounds(x, y)) return; void* addr = &data_[pixel_address(x, y)]; *reinterpret_cast<uint32_t*>(addr) = color; } private: bool pixel_in_bounds(int x, int y) const { return x >= 0 && x < w_ && y >= 0 && y < h_; } size_t pixel_address(int x, int y) const { return (y * w_ + x) * 4; } // Pixel dimensions of the image. int w_; int h_; std::vector<unsigned char> data_; }; float CalculateDifferencePercentage(const Image& actual, int pixels_different) { // 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 CountImageSizeMismatchAsPixelDifference(const Image& baseline, const Image& actual, int* pixels_different) { int w = std::min(baseline.w(), actual.w()); int h = std::min(baseline.h(), actual.h()); // 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; } 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; } } CountImageSizeMismatchAsPixelDifference(baseline, actual, &pixels_different); return CalculateDifferencePercentage(actual, pixels_different); } // 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; } } CountImageSizeMismatchAsPixelDifference(baseline, actual, &pixels_different); return CalculateDifferencePercentage(actual, pixels_different); } 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* const diff_name = compare_histograms ? "exact diff" : "diff"; float percent = PercentageDifferent(actual_image, baseline_image); const char* const 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; } 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++]; if (i < argc) filename2 = argv[i++]; if (i < argc) diff_filename = argv[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; }