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

3 files changed, 239 insertions, 0 deletions

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
+}
diff --git a/printing/image.h b/printing/image.h
new file mode 100644
index 0000000..8ef1007
--- /dev/null
+++ b/printing/image.h
@@ -0,0 +1,75 @@
+// Copyright (c) 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.
+
+#ifndef PRINTING_IMAGE_H_
+#define PRINTING_IMAGE_H_
+
+#include <string>
+#include <vector>
+
+#include "base/basictypes.h"
+#include "base/gfx/size.h"
+#include "base/logging.h"
+
+namespace printing {
+
+// Lightweight raw-bitmap management. The image, once initialized, is immuable.
+// The main purpose is testing image contents.
+class Image {
+ public:
+  // Creates the image from the given filename on disk.  Uses extension to
+  // defer file type. PNG and EMF (on Windows) currently supported.
+  // If image loading fails size().IsEmpty() will be true.
+  explicit Image(const std::wstring& filename);
+
+  const gfx::Size& size() const {
+    return size_;
+  }
+
+  // Save image as PNG.
+  bool SaveToPng(const std::wstring& filename);
+
+  // Returns % of pixels different
+  double PercentageDifferent(const Image& rhs) const;
+
+  // Returns the 0x0RGB or 0xARGB value of the pixel at the given location.
+  uint32 Color(uint32 color) const {
+    if (ignore_alpha_)
+      return color & 0xFFFFFF;  // Strip out A.
+    else
+      return color;
+  }
+
+  uint32 pixel_at(int x, int y) const {
+    DCHECK(x >= 0 && x < size_.width());
+    DCHECK(y >= 0 && y < size_.height());
+    const uint32* data = reinterpret_cast<const uint32*>(&*data_.begin());
+    const uint32* data_row = data + y * row_length_ / sizeof(uint32);
+    return Color(data_row[x]);
+  }
+
+ private:
+  bool LoadPng(const std::string& compressed);
+
+  bool LoadMetafile(const std::string& data);
+
+  // Pixel dimensions of the image.
+  gfx::Size size_;
+
+  // Length of a line in bytes.
+  int row_length_;
+
+  // Actual bitmap data in arrays of RGBAs (so when loaded as uint32, it's
+  // 0xABGR).
+  std::vector<unsigned char> data_;
+
+  // Flag to signal if the comparison functions should ignore the alpha channel.
+  const bool ignore_alpha_;  // Currently always true.
+
+  DISALLOW_EVIL_CONSTRUCTORS(Image);
+};
+
+}  // namespace printing
+
+#endif  // PRINTING_IMAGE_H_
diff --git a/printing/printing.gyp b/printing/printing.gyp
index 8dd7a59..e199de8 100644
--- a/printing/printing.gyp
+++ b/printing/printing.gyp
@@ -29,6 +29,8 @@
       'sources': [
         'emf_win.cc',
         'emf_win.h',
+        'image.cc',
+        'image.h',
         'native_metafile.h',
         'page_number.cc',
         'page_number.h',