Backport PNG output format to origin/master branch.

The pdfium library itself does not support the format, but the test utility
can convert to this output format.

GN build can't be tested standalone, so push this out to the next CL.

R=jam@chromium.org

Review URL: https://codereview.chromium.org/950113002

1 files changed, 398 insertions, 0 deletions

diff --git a/samples/image_diff.cc b/samples/image_diff.cc
new file mode 100644
index 0000000000..3f82b66527
--- /dev/null
+++ b/samples/image_diff.cc
@@ -0,0 +1,398 @@
+// 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;
+}