add SkCanvas::NewRaster factory -- a very common use-case in chrome

src/core/SkCanvas.cpp

 
 /*
  * Copyright 2008 The Android Open Source Project
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 
 #include "SkCanvas.h"
@@ skipping 2287 matching lines @@
     return *paint;
 }
 
 const SkRegion& SkCanvas::LayerIter::clip() const { return fImpl->getClip(); }
 int SkCanvas::LayerIter::x() const { return fImpl->getX(); }
 int SkCanvas::LayerIter::y() const { return fImpl->getY(); }
 
 ///////////////////////////////////////////////////////////////////////////////
 
 SkCanvas::ClipVisitor::~ClipVisitor() { }
+
+///////////////////////////////////////////////////////////////////////////////
+
+SkCanvas* SkCanvas::NewRaster(const SkImageInfo& info) {
+    SkBitmap bitmap;
+    if (!bitmap.allocPixels(info)) {
+        return NULL;
+    }
+
+    // should this functionality be moved into allocPixels()?
+    if (kOpaque_SkAlphaType != info.alphaType()) {
+        bitmap.eraseColor(0);

[scroggo, 2014/02/27 19:16:06]

Same.

+    }
+    return SkNEW_ARGS(SkCanvas, (bitmap));
+}