Implement canvas's globalCompositeOperation lighter properly....

skia/effects/SkLayerRasterizer.cpp

 /* libs/graphics/effects/SkLayerRasterizer.cpp
 **
 ** Copyright 2006, The Android Open Source Project
 **
 ** Licensed under the Apache License, Version 2.0 (the "License"); 
 ** you may not use this file except in compliance with the License. 
 ** You may obtain a copy of the License at 
 **
 **     http://www.apache.org/licenses/LICENSE-2.0 
 **
@@ skipping 90 matching lines @@
     if (SkMask::kJustRenderImage_CreateMode != mode)
     {
         if (!compute_bounds(fLayers, path, matrix, clipBounds, &mask->fBounds))
             return false;
     }
 
     if (SkMask::kComputeBoundsAndRenderImage_CreateMode == mode)
     {
         mask->fFormat   = SkMask::kA8_Format;
         mask->fRowBytes = SkToU16(mask->fBounds.width());
-        mask->fImage = SkMask::AllocImage(mask->computeImageSize());
-        memset(mask->fImage, 0, mask->computeImageSize());
+        size_t size = mask->computeImageSize();
+        if (0 == size) {
+            return false;   // too big to allocate, abort
+        }
+        mask->fImage = SkMask::AllocImage(size);
+        memset(mask->fImage, 0, size);
     }
 
     if (SkMask::kJustComputeBounds_CreateMode != mode)
     {    
         SkBitmap device;
         SkDraw   draw;
         SkMatrix translatedMatrix;  // this translates us to our local pixels
         SkMatrix drawMatrix;        // this translates the path by each layer's offset
         SkRegion rectClip;
         
@@ skipping 110 matching lines @@
 SkFlattenable* SkLayerRasterizer::CreateProc(SkFlattenableReadBuffer& buffer)
 {
     return SkNEW_ARGS(SkLayerRasterizer, (buffer));
 }
 
 SkFlattenable::Factory SkLayerRasterizer::getFactory()
 {
     return CreateProc;
 }