Adjust the CoreGraphics context for offscreen layers.

skia/ext/skia_utils_mac.mm

 // 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.
 
 #include "skia/ext/skia_utils_mac.h"
 
 #import <AppKit/AppKit.h>
 
 #include "base/logging.h"
 #include "base/mac/mac_util.h"
@@ skipping 289 matching lines @@
       cgContext_(0) {
 }
 
 SkiaBitLocker::~SkiaBitLocker() {
   releaseIfNeeded();
 }
 
 void SkiaBitLocker::releaseIfNeeded() {
   if (!cgContext_)
     return;
-  canvas_->getDevice()->accessBitmap(true).unlockPixels();
+  canvas_->getTopDevice()->accessBitmap(true).unlockPixels();
   CGContextRelease(cgContext_);
   cgContext_ = 0;
 }
 
 CGContextRef SkiaBitLocker::cgContext() {
-  SkDevice* device = canvas_->getDevice();
+  SkDevice* device = canvas_->getTopDevice();
   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());
+  const SkIPoint& pt = device->getOrigin();
   for (; !iter.done(); iter.next()) {
-    const SkIRect& skRect = iter.rect();
+    SkIRect skRect = iter.rect();
+    skRect.offset(-pt);
     CGRect cgRect = SkIRectToCGRect(skRect);
     CGPathAddRect(clipPath, 0, cgRect);
   }
   CGContextAddPath(cgContext_, clipPath);
   CGContextClip(cgContext_);
   CGPathRelease(clipPath);
 
   // Apply content matrix.
-  const SkMatrix& skMatrix = canvas_->getTotalMatrix();
+  SkMatrix skMatrix = canvas_->getTotalMatrix();
+  skMatrix.postTranslate(-SkIntToScalar(pt.fX), -SkIntToScalar(pt.fY));
   CGAffineTransform affine = SkMatrixToCGAffineTransform(skMatrix);
   CGContextConcatCTM(cgContext_, affine);
   
   return cgContext_;
 }
 
 }  // namespace gfx