Send array of paint rects and bitmaps as opposed to a Union

skia/ext/bitmap_platform_device_mac.cc

 // Copyright (c) 2006-2008 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/bitmap_platform_device_mac.h"
 
 #include <time.h>
 
 #include "base/ref_counted.h"
 #include "skia/ext/skia_utils_mac.h"
@@ skipping 96 matching lines @@
   SkASSERT(bitmap_context_);
   // Initialize the clip region to the entire bitmap.
 
   SkIRect rect;
   rect.set(0, 0,
            CGBitmapContextGetWidth(bitmap_context_),
            CGBitmapContextGetHeight(bitmap_context_));
   clip_region_ = SkRegion(rect);
   transform_.reset();
   CGContextRetain(bitmap_context_);
+  // We must save the state once so that we can use the restore/save trick
+  // in LoadConfig().
+  CGContextSaveGState(bitmap_context_);
 }
 
 void BitmapPlatformDeviceMac::BitmapPlatformDeviceMacData::SetMatrixClip(
     const SkMatrix& transform,
     const SkRegion& region) {
   transform_ = transform;
   clip_region_ = region;
   config_dirty_ = true;
 }
 
 void BitmapPlatformDeviceMac::BitmapPlatformDeviceMacData::LoadConfig() {
   if (!config_dirty_ || !bitmap_context_)
     return;  // Nothing to do.
   config_dirty_ = false;
 
   // Transform.
   SkMatrix t(transform_);
+
+  // We must restore and then save the state of the graphics context since the
+  // calls to Load the clipping region to the context are strictly cummulative,
+  // i.e., you can't replace a clip rect, other than with a save/restore.
+  // But this implies that no other changes to the state are done elsewhere.
+  // If we ever get to need to change this, then we must replace the clip rect
+  // calls in LoadClippingRegionToCGContext() with an image mask instead.
+  CGContextRestoreGState(bitmap_context_);
+  CGContextSaveGState(bitmap_context_);
   LoadTransformToCGContext(bitmap_context_, t);
   t.setTranslateX(-t.getTranslateX());
   t.setTranslateY(-t.getTranslateY());
   LoadClippingRegionToCGContext(bitmap_context_, clip_region_, t);
 }
 
 
 // We use this static factory function instead of the regular constructor so
 // that we can create the pixel data before calling the constructor. This is
 // required so that we can call the base class' constructor with the pixel
@@ skipping 144 matching lines @@
     for (int i = 0; i < height; i++) {
       size_t offset = (i + bitmap_start_y) * row_words + bitmap_start_x;
       for (int j = 0; j < width; j++) {
         adjustor(data + offset + j);
       }
     }
   }
 }
 
 }  // namespace skia