Use CGImage for conversion to SkBitmap.

This has two advantages: we can convert a CGImage without building an
UIImage first and the convertion can happen on any thread, not just
the main thread.

BUG=


Review URL: https://chromiumcodereview.appspot.com/11362164

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@166900 0039d316-1c4b-4281-b951-d872f2087c98

2 files changed, 7 insertions, 18 deletions

diff --git a/skia/ext/skia_utils_ios.h b/skia/ext/skia_utils_ios.h
index 7b49baa..f213cf0 100644
--- a/skia/ext/skia_utils_ios.h
+++ b/skia/ext/skia_utils_ios.h
@@ -18,8 +18,10 @@ class UIImage;
 
 namespace gfx {
 
-// Draws a UIImage with a given size into a SkBitmap.
-SK_API SkBitmap UIImageToSkBitmap(UIImage* image, CGSize size, bool is_opaque);
+// Draws a CGImage into an SkBitmap of the given size.
+SK_API SkBitmap CGImageToSkBitmap(CGImageRef image,
+                                  CGSize size,
+                                  bool is_opaque);
 
 // Given an SkBitmap and a color space, return an autoreleased UIImage.
 SK_API UIImage* SkBitmapToUIImageWithColorSpace(const SkBitmap& skia_bitmap,
diff --git a/skia/ext/skia_utils_ios.mm b/skia/ext/skia_utils_ios.mm
index 686f30e..fba12df 100644
--- a/skia/ext/skia_utils_ios.mm
+++ b/skia/ext/skia_utils_ios.mm
@@ -12,7 +12,7 @@
 
 namespace gfx {
 
-SkBitmap UIImageToSkBitmap(UIImage* image, CGSize size, bool is_opaque) {
+SkBitmap CGImageToSkBitmap(CGImageRef image, CGSize size, bool is_opaque) {
   SkBitmap bitmap;
   if (!image)
     return bitmap;
@@ -47,21 +47,8 @@ SkBitmap UIImageToSkBitmap(UIImage* image, CGSize size, bool is_opaque) {
   if (!context)
     return bitmap;
 
-  // We need to invert the y-axis of the canvas so that Core Graphics drawing
-  // happens right-side up. Skia has an upper-left origin and CG has a lower-
-  // left one.
-  CGContextScaleCTM(context, 1.0, -1.0);
-  CGContextTranslateCTM(context, 0, -size.height);
-
-  // UIGraphicsPushContext be called from the main thread.
-  // TODO(rohitrao): We can use CG to make this thread safe, but the mac code
-  // calls setCurrentContext, so it's similarly limited to the main thread.
-  DCHECK([NSThread isMainThread]);
-  UIGraphicsPushContext(context);
-  [image drawInRect:CGRectMake(0, 0, size.width, size.height)
-          blendMode:kCGBlendModeCopy
-              alpha:1.0];
-  UIGraphicsPopContext();
+  CGRect imageRect = CGRectMake(0.0, 0.0, size.width, size.height);
+  CGContextDrawImage(context, imageRect, image);
 
   return bitmap;
 }