3 files changed, 136 insertions, 2 deletions
diff --git a/skia/ext/skia_utils_mac.h b/skia/ext/skia_utils_mac.h
index 04d4a1d..fb9a66d 100644
--- a/skia/ext/skia_utils_mac.h
+++ b/skia/ext/skia_utils_mac.h
@@ -1,4 +1,4 @@
-// Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -15,6 +15,7 @@ struct SkIRect;
 struct SkPoint;
 struct SkRect;
 class SkBitmap;
+class SkCanvas;
 class SkMatrix;
 #ifdef __LP64__
 typedef CGSize NSSize;
@@ -86,6 +87,20 @@ NSImage* SkBitmapsToNSImage(const std::vector<const SkBitmap*>& bitmaps);
 // Returns |[NSImage imageNamed:@"NSApplicationIcon"]| as SkBitmap.
 SkBitmap AppplicationIconAtSize(int size);
 
+// Converts a SkCanvas temporarily to a CGContext
+class SkiaBitLocker {
+ public:
+  explicit SkiaBitLocker(SkCanvas* canvas);
+  ~SkiaBitLocker();
+  CGContextRef cgContext();
+
+ private:
+  void releaseIfNeeded();
+  SkCanvas* canvas_;
+  CGContextRef cgContext_;
+};
+
+
 }  // namespace gfx
 
 #endif  // SKIA_EXT_SKIA_UTILS_MAC_H_
diff --git a/skia/ext/skia_utils_mac.mm b/skia/ext/skia_utils_mac.mm
index 5547c4a..ecb30ca 100644
--- a/skia/ext/skia_utils_mac.mm
+++ b/skia/ext/skia_utils_mac.mm
@@ -7,10 +7,12 @@
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
+#include "base/mac/mac_util.h"
 #include "base/mac/scoped_cftyperef.h"
 #include "base/memory/scoped_nsobject.h"
 #include "base/memory/scoped_ptr.h"
 #include "skia/ext/bitmap_platform_device_mac.h"
+#include "third_party/skia/include/core/SkRegion.h"
 #include "third_party/skia/include/utils/mac/SkCGUtils.h"
 #include "ui/gfx/scoped_ns_graphics_context_save_gstate_mac.h"
 
@@ -284,4 +286,61 @@ SkBitmap AppplicationIconAtSize(int size) {
   return NSImageToSkBitmap(image, NSMakeSize(size, size), /* is_opaque=*/true);
 }
 
+
+SkiaBitLocker::SkiaBitLocker(SkCanvas* canvas)
+    : canvas_(canvas),
+      cgContext_(0) {
+}
+
+SkiaBitLocker::~SkiaBitLocker() {
+  releaseIfNeeded();
+}
+
+void SkiaBitLocker::releaseIfNeeded() {
+  if (!cgContext_)
+    return;
+  canvas_->getDevice()->accessBitmap(true).unlockPixels();
+  CGContextRelease(cgContext_);
+  cgContext_ = 0;
+}
+
+CGContextRef SkiaBitLocker::cgContext() {
+  SkDevice* device = canvas_->getDevice();
+  DCHECK(device);
+  if (!device)
+    return 0;
+  releaseIfNeeded();
+  const SkBitmap& bitmap = device->accessBitmap(true);
+  bitmap.lockPixels();
+  void* pixels = bitmap.getPixels();
+  cgContext_ = CGBitmapContextCreate(pixels, device->width(),
+    device->height(), 8, bitmap.rowBytes(), CGColorSpaceCreateDeviceRGB(), 
+    kCGBitmapByteOrder32Host | kCGImageAlphaPremultipliedFirst);
+
+  // Apply device matrix.
+  CGAffineTransform contentsTransform = CGAffineTransformMakeScale(1, -1);
+  contentsTransform = CGAffineTransformTranslate(contentsTransform, 0,
+      -device->height());
+  CGContextConcatCTM(cgContext_, contentsTransform);
+
+  // Apply clip in device coordinates.
+  CGMutablePathRef clipPath = CGPathCreateMutable();
+  SkRegion::Iterator iter(canvas_->getTotalClip());
+  for (; !iter.done(); iter.next()) {
+    const SkIRect& skRect = iter.rect();
+    CGRect cgRect = SkIRectToCGRect(skRect);
+    CGPathAddRect(clipPath, 0, cgRect);
+  }
+  CGContextAddPath(cgContext_, clipPath);
+  CGContextClip(cgContext_);
+  CGPathRelease(clipPath);
+
+  // Apply content matrix.
+  const SkMatrix& skMatrix = canvas_->getTotalMatrix();
+  CGAffineTransform affine = SkMatrixToCGAffineTransform(skMatrix);
+  CGContextConcatCTM(cgContext_, affine);
+  
+  return cgContext_;
+}
+
 }  // namespace gfx
diff --git a/skia/ext/skia_utils_mac_unittest.mm b/skia/ext/skia_utils_mac_unittest.mm
index 132c6ac..b2175cd 100644
--- a/skia/ext/skia_utils_mac_unittest.mm
+++ b/skia/ext/skia_utils_mac_unittest.mm
@@ -1,4 +1,4 @@
-// Copyright (c) 2009 The Chromium Authors. All rights reserved.
+// 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.
 
@@ -21,6 +21,14 @@ class SkiaUtilsMacTest : public testing::Test {
   // Checks that the given bitmap is actually red or blue.
   void TestSkBitmap(const SkBitmap& bitmap, bool isred);
 
+  enum BitLockerTest {
+    TestIdentity = 0,
+    TestTranslate = 1,
+    TestClip = 2,
+    TestXClip = TestTranslate | TestClip
+  };
+  void RunBitLockerTest(BitLockerTest test);
+
   // If not red, is blue.
   // If not tfbit (twenty-four-bit), is 444.
   void ShapeHelper(int width, int height, bool isred, bool tfbit);
@@ -101,6 +109,41 @@ void SkiaUtilsMacTest::TestSkBitmap(const SkBitmap& bitmap, bool isred) {
   EXPECT_GT(SkColorGetA(color), 245u);
 }
 
+void SkiaUtilsMacTest::RunBitLockerTest(BitLockerTest test) {
+  const unsigned width = 2;
+  const unsigned height = 2;
+  const unsigned storageSize = width * height;
+  const unsigned original[] = {0xFF333333, 0xFF666666, 0xFF999999, 0xFFCCCCCC};
+  EXPECT_EQ(storageSize, sizeof(original) / sizeof(original[0]));
+  unsigned bits[storageSize];
+  memcpy(bits, original, sizeof(original));
+  SkBitmap bitmap;
+  bitmap.setConfig(SkBitmap::kARGB_8888_Config, width, height);
+  bitmap.setPixels(bits);
+  SkCanvas canvas;
+  canvas.setBitmapDevice(bitmap);
+  if (test & TestTranslate)
+    canvas.translate(width / 2, 0);
+  if (test & TestClip) {
+    SkRect clipRect = {0, height / 2, width, height};
+    canvas.clipRect(clipRect);
+  }
+  gfx::SkiaBitLocker bitLocker(&canvas);
+  CGContextRef cgContext = bitLocker.cgContext();
+  CGColorRef testColor = CGColorGetConstantColor(kCGColorWhite);
+  CGContextSetFillColorWithColor(cgContext, testColor);
+  CGRect cgRect = {{0, 0}, {width, height}};
+  CGContextFillRect(cgContext, cgRect);
+  const unsigned results[][storageSize] = {
+    {0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF}, // identity
+    {0xFF333333, 0xFFFFFFFF, 0xFF999999, 0xFFFFFFFF}, // translate
+    {0xFF333333, 0xFF666666, 0xFFFFFFFF, 0xFFFFFFFF}, // clip
+    {0xFF333333, 0xFF666666, 0xFF999999, 0xFFFFFFFF}  // translate | clip
+  };
+  for (unsigned index = 0; index < storageSize; index++)
+    EXPECT_EQ(results[test][index], bits[index]);
+}
+
 void SkiaUtilsMacTest::ShapeHelper(int width, int height,
                                    bool isred, bool tfbit) {
   SkBitmap thing(CreateSkBitmap(width, height, isred, tfbit));
@@ -172,4 +215,21 @@ TEST_F(SkiaUtilsMacTest, NSImageRepToSkBitmap) {
   TestSkBitmap(bitmap, isred);
 }
 
+TEST_F(SkiaUtilsMacTest, BitLocker_Identity) {
+  RunBitLockerTest(SkiaUtilsMacTest::TestIdentity);
+}
+
+TEST_F(SkiaUtilsMacTest, BitLocker_Translate) {
+  RunBitLockerTest(SkiaUtilsMacTest::TestTranslate);
+}
+
+TEST_F(SkiaUtilsMacTest, BitLocker_Clip) {
+  RunBitLockerTest(SkiaUtilsMacTest::TestClip);
+}
+
+TEST_F(SkiaUtilsMacTest, BitLocker_XClip) {
+  RunBitLockerTest(SkiaUtilsMacTest::TestXClip);
+}
+
 }  // namespace
+