Extract Image class so it can be used in more tests.

BUG=none
TEST=none (no functional change).

Review URL: http://codereview.chromium.org/149410

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@20491 0039d316-1c4b-4281-b951-d872f2087c98

diff --git a/printing/image.cc b/printing/image.cc
new file mode 100644
index 0000000..8f397d8
--- /dev/null
+++ b/printing/image.cc

@@ -0,0 +1,162 @@
+// Copyright (c) 2006-2009 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.
+
+#include "printing/image.h"
+
+#include "base/file_util.h"
+#include "base/gfx/png_decoder.h"
+#include "base/gfx/png_encoder.h"
+#include "base/gfx/rect.h"
+#include "base/string_util.h"
+#include "printing/native_metafile.h"
+#include "skia/ext/platform_device.h"
+
+#if defined(OS_WIN)
+#include "base/gfx/gdi_util.h"  // EMF support
+#endif
+
+printing::Image::Image(const std::wstring& filename) : ignore_alpha_(true) {
+  std::string data;
+  file_util::ReadFileToString(filename, &data);
+  std::wstring ext = file_util::GetFileExtensionFromPath(filename);
+  bool success = false;
+  if (LowerCaseEqualsASCII(ext, "png")) {
+    success = LoadPng(data);
+  } else if (LowerCaseEqualsASCII(ext, "emf")) {
+    success = LoadMetafile(data);
+  } else {
+    DCHECK(false);
+  }
+  if (!success) {
+    size_.SetSize(0, 0);
+    row_length_ = 0;
+    data_.clear();
+  }
+}
+
+bool printing::Image::SaveToPng(const std::wstring& filename) {
+  DCHECK(!data_.empty());
+  std::vector<unsigned char> compressed;
+  bool success = PNGEncoder::Encode(&*data_.begin(),
+                                    PNGEncoder::FORMAT_BGRA,
+                                    size_.width(),
+                                    size_.height(),
+                                    row_length_,
+                                    true,
+                                    &compressed);
+  DCHECK(success && compressed.size());
+  if (success) {
+    int write_bytes = file_util::WriteFile(
+        filename,
+        reinterpret_cast<char*>(&*compressed.begin()), compressed.size());
+    success = (write_bytes == static_cast<int>(compressed.size()));
+    DCHECK(success);
+  }
+  return success;
+}
+
+double printing::Image::PercentageDifferent(const Image& rhs) const {
+  if (size_.width() == 0 || size_.height() == 0 ||
+    rhs.size_.width() == 0 || rhs.size_.height() == 0)
+    return 100.;
+
+  int width = std::min(size_.width(), rhs.size_.width());
+  int height = std::min(size_.height(), rhs.size_.height());
+  // Compute pixels different in the overlap
+  int pixels_different = 0;
+  for (int y = 0; y < height; ++y) {
+    for (int x = 0; x < width; ++x) {
+      uint32 lhs_pixel = pixel_at(x, y);
+      uint32 rhs_pixel = rhs.pixel_at(x, y);
+      if (lhs_pixel != rhs_pixel)
+        ++pixels_different;
+    }
+
+    // Look for extra right lhs pixels. They should be white.
+    for (int x = width; x < size_.width(); ++x) {
+      uint32 lhs_pixel = pixel_at(x, y);
+      if (lhs_pixel != Color(SK_ColorWHITE))
+        ++pixels_different;
+    }
+
+    // Look for extra right rhs pixels. They should be white.
+    for (int x = width; x < rhs.size_.width(); ++x) {
+      uint32 rhs_pixel = rhs.pixel_at(x, y);
+      if (rhs_pixel != Color(SK_ColorWHITE))
+        ++pixels_different;
+    }
+  }
+
+  // Look for extra bottom lhs pixels. They should be white.
+  for (int y = height; y < size_.height(); ++y) {
+    for (int x = 0; x < size_.width(); ++x) {
+      uint32 lhs_pixel = pixel_at(x, y);
+      if (lhs_pixel != Color(SK_ColorWHITE))
+        ++pixels_different;
+    }
+  }
+
+  // Look for extra bottom rhs pixels. They should be white.
+  for (int y = height; y < rhs.size_.height(); ++y) {
+    for (int x = 0; x < rhs.size_.width(); ++x) {
+      uint32 rhs_pixel = rhs.pixel_at(x, y);
+      if (rhs_pixel != Color(SK_ColorWHITE))
+        ++pixels_different;
+    }
+  }
+
+  // Like the WebKit ImageDiff tool, we define percentage different in terms
+  // of the size of the 'actual' bitmap.
+  double total_pixels = static_cast<double>(size_.width()) *
+      static_cast<double>(height);
+  return static_cast<double>(pixels_different) / total_pixels * 100.;
+}
+
+bool printing::Image::LoadPng(const std::string& compressed) {
+  int w;
+  int h;
+  bool success = PNGDecoder::Decode(
+      reinterpret_cast<const unsigned char*>(compressed.c_str()),
+      compressed.size(), PNGDecoder::FORMAT_BGRA, &data_, &w, &h);
+  size_.SetSize(w, h);
+  row_length_ = size_.width() * sizeof(uint32);
+  return success;
+}
+
+bool printing::Image::LoadMetafile(const std::string& data) {
+  DCHECK(!data.empty());
+#if defined(OS_WIN)
+  printing::NativeMetafile metafile;
+  metafile.CreateFromData(data.data(), data.size());
+  gfx::Rect rect(metafile.GetBounds());
+  // Create a temporary HDC and bitmap to retrieve the rendered data.
+  HDC hdc = CreateCompatibleDC(NULL);
+  BITMAPV4HEADER hdr;
+  DCHECK_EQ(rect.x(), 0);
+  DCHECK_EQ(rect.y(), 0);
+  DCHECK_GT(rect.width(), 0);
+  DCHECK_GT(rect.height(), 0);
+  size_ = rect.size();
+  gfx::CreateBitmapV4Header(rect.width(), rect.height(), &hdr);
+  void* bits;
+  HBITMAP bitmap = CreateDIBSection(hdc,
+                                    reinterpret_cast<BITMAPINFO*>(&hdr), 0,
+                                    &bits, NULL, 0);
+  DCHECK(bitmap);
+  DCHECK(SelectObject(hdc, bitmap));
+  skia::PlatformDevice::InitializeDC(hdc);
+  bool success = metafile.Playback(hdc, NULL);
+  row_length_ = size_.width() * sizeof(uint32);
+  size_t bytes = row_length_ * size_.height();
+  DCHECK(bytes);
+  data_.resize(bytes);
+  memcpy(&*data_.begin(), bits, bytes);
+  DeleteDC(hdc);
+  DeleteObject(bitmap);
+  return success;
+#else
+  NOTIMPLEMENTED();
+  return false;
+#endif
+}