Add an image diff link to failed layout tests.

Review URL: http://codereview.chromium.org/18023

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@8119 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 101 insertions, 5 deletions

diff --git a/chrome/tools/test/image_diff/image_diff.cc b/chrome/tools/test/image_diff/image_diff.cc
index 7fa6f48..c21003d 100644
--- a/chrome/tools/test/image_diff/image_diff.cc
+++ b/chrome/tools/test/image_diff/image_diff.cc
@@ -17,25 +17,41 @@
 #include "base/command_line.h"
 #include "base/file_util.h"
 #include "base/gfx/png_decoder.h"
+#include "base/gfx/png_encoder.h"
 #include "base/logging.h"
 #include "base/process_util.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"
 
+#if defined(OS_WIN)
+#include "windows.h"
+#endif
+
 // Causes the app to remain open, waiting for pairs of filenames on stdin.
 // The caller is then responsible for terminating this app.
 static const wchar_t kOptionPollStdin[] = L"use-stdin";
+static const wchar_t kOptionGenerateDiff[] = L"diff";
 
 // 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 RGBA_RED = 0x000000ff;
+static const uint32 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;
   }
@@ -48,6 +64,10 @@ class Image {
     return h_;
   }
 
+  const unsigned char* data() const {
+    return &data_.front();
+  }
+
   // Creates the image from stdin with the given data length. On success, it
   // will return true. On failure, no other methods should be accessed.
   bool CreateFromStdin(size_t byte_length) {
@@ -97,10 +117,17 @@ class Image {
   }
 
   // Returns the RGBA value of the pixel at the given location
-  uint32 pixel_at(int x, int y) const {
+  const uint32 pixel_at(int x, int y) const {
+    DCHECK(x >= 0 && x < w_);
+    DCHECK(y >= 0 && y < h_);
+    return *reinterpret_cast<const uint32*>(&(data_[(y * w_ + x) * 4]));
+  }
+
+  void set_pixel_at(int x, int y, uint32 color) const {
     DCHECK(x >= 0 && x < w_);
     DCHECK(y >= 0 && y < h_);
-    return data_[(y * w_ + x) * 4];
+    void* addr = &const_cast<unsigned char*>(&data_.front())[(y * w_ + x) * 4];
+    *reinterpret_cast<uint32*>(addr) = color;
   }
 
  private:
@@ -149,7 +176,10 @@ void PrintHelp() {
     "    Compares two files on disk, returning 0 when they are the same\n"
     "  image_diff --use-stdin\n"
     "    Stays open reading pairs of filenames from stdin, comparing them,\n"
-    "    and sending 0 to stdout when they are the same\n");
+    "    and sending 0 to stdout when they are the same\n"
+    "  image_diff --diff <compare file> <reference file> <output file>\n"
+    "    Compares two files on disk, outputs an image that visualizes the"
+    "    difference to <output file>\n");
   /* For unfinished webkit-like-mode (see below)
     "\n"
     "  image_diff -s\n"
@@ -232,10 +262,68 @@ int CompareImages(const char* file1, const char* file2) {
 */
 }
 
+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 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 alpha = base_pixel & RGBA_ALPHA;
+        uint32 new_pixel = base_pixel - ((alpha / 2) & RGBA_ALPHA);
+        out->set_pixel_at(x, y, new_pixel);
+      }
+    }
+  }
+
+  return same;
+}
+
+int DiffImages(const char* file1, const char* file2, const char* out_file) {
+  Image actual_image;
+  Image baseline_image;
+
+  if (!actual_image.CreateFromFilename(file1)) {
+    fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file1);
+    return kStatusError;
+  }
+  if (!baseline_image.CreateFromFilename(file2)) {
+    fprintf(stderr, "image_diff: Unable to open file \"%s\"\n", file2);
+    return kStatusError;
+  }
+
+  Image diff_image;
+  bool same = CreateImageDiff(baseline_image, actual_image, &diff_image);
+  if (same)
+    return kStatusSame;
+
+  std::vector<unsigned char> png_encoding;
+  PNGEncoder::Encode(diff_image.data(),  PNGEncoder::FORMAT_RGBA,
+                     diff_image.w(), diff_image.h(), diff_image.w() * 4,
+                     false, &png_encoding);
+  if (file_util::WriteFile(UTF8ToWide(out_file),
+      reinterpret_cast<char*>(&png_encoding.front()), png_encoding.size()) < 0)
+    return kStatusError;
+
+  return kStatusDifferent;
+}
+
 int main(int argc, const char* argv[]) {
   base::EnableTerminationOnHeapCorruption();
+  // TODO(estade): why does using the default constructor (command line
+  // singleton) cause an exception when run in debug mode?
 #if defined(OS_WIN)
-  CommandLine parsed_command_line;
+  CommandLine parsed_command_line(::GetCommandLine());
 #elif defined(OS_POSIX)
   CommandLine parsed_command_line(argc, argv);
 #endif
@@ -265,7 +353,15 @@ int main(int argc, const char* argv[]) {
     return 0;
   }
 
-  if (argc == 3) {
+  if (parsed_command_line.HasSwitch(kOptionGenerateDiff)) {
+    if (3 == parsed_command_line.GetLooseValueCount()) {
+      CommandLine::LooseValueIterator iter =
+          parsed_command_line.GetLooseValuesBegin();
+      return DiffImages(WideToUTF8(*iter).c_str(),
+                        WideToUTF8(*(iter + 1)).c_str(),
+                        WideToUTF8(*(iter + 2)).c_str());
+    }
+  } else if (2 == parsed_command_line.GetLooseValueCount()) {
     return CompareImages(argv[1], argv[2]);
   }