Support currentTransform in 2D Canvas.

Source/core/html/canvas/CanvasRenderingContext2D.h

 /*
  * Copyright (C) 2006, 2007, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 39 matching lines @@
 class DOMPath;
 class Element;
 class ExceptionState;
 class FloatRect;
 class GraphicsContext;
 class HTMLCanvasElement;
 class HTMLImageElement;
 class HTMLVideoElement;
 class ImageBitmap;
 class ImageData;
+class SVGMatrix;
 class TextMetrics;
 
 typedef HashMap<String, RefPtr<MutableStylePropertySet> > MutableStylePropertyMap;
 
 class CanvasRenderingContext2D : public CanvasRenderingContext, public CanvasPathMethods {
 public:
     static PassOwnPtr<CanvasRenderingContext2D> create(HTMLCanvasElement* canvas, const Canvas2DContextAttributes* attrs, bool usesCSSCompatibilityParseMode)
     {
         return adoptPtr(new CanvasRenderingContext2D(canvas, attrs, usesCSSCompatibilityParseMode));
     }
@@ skipping 40 matching lines @@
 
     float globalAlpha() const;
     void setGlobalAlpha(float);
 
     String globalCompositeOperation() const;
     void setGlobalCompositeOperation(const String&);
 
     void save() { ++m_unrealizedSaveCount; }
     void restore();
 
+    SVGMatrix currentTransform() const;

[Justin Novosad, 2013/09/19 19:23:48]

IIRC, you can't return an incomplete type.  If this code compiles as is, you
probably don't need the above forward declaration. Also, it is returning by
value, which may not be the best thing to do here.  Maybe you could make this
function an inline so that the compiler can optimize-out the transient copy of
the return value. http://en.wikipedia.org/wiki/Return_value_optimization

+    void setCurrentTransform(const SVGMatrix&);
     void scale(float sx, float sy);
     void rotate(float angleInRadians);
     void translate(float tx, float ty);
     void transform(float m11, float m12, float m21, float m22, float dx, float dy);
     void setTransform(float m11, float m12, float m21, float m22, float dx, float dy);
     void resetTransform();
 
     void setStrokeColor(const String& color);
     void setStrokeColor(float grayLevel);
     void setStrokeColor(const String& color, float alpha);
@@ skipping 205 matching lines @@
     Vector<State, 1> m_stateStack;
     unsigned m_unrealizedSaveCount;
     bool m_usesCSSCompatibilityParseMode;
     bool m_hasAlpha;
     MutableStylePropertyMap m_fetchedFonts;
 };
 
 } // namespace WebCore
 
 #endif