Support currentTransform in 2D Canvas.

Source/core/html/canvas/CanvasRenderingContext2D.cpp

 /*
  * Copyright (C) 2004, 2005, 2006, 2007, 2008, 2009, 2010, 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2008, 2010 Nokia Corporation and/or its subsidiary(-ies)
  * Copyright (C) 2007 Alp Toker <alp@atoker.com>
  * Copyright (C) 2008 Eric Seidel <eric@webkit.org>
  * Copyright (C) 2008 Dirk Schulze <krit@webkit.org>
  * Copyright (C) 2010 Torch Mobile (Beijing) Co. Ltd. All rights reserved.
  * Copyright (C) 2012, 2013 Intel Corporation. All rights reserved.
  * Copyright (C) 2013 Adobe Systems Incorporated. All rights reserved.
  *
@@ skipping 578 matching lines @@
         return;
     realizeSaves();
     modifiableState().m_globalComposite = op;
     modifiableState().m_globalBlend = blendMode;
     GraphicsContext* c = drawingContext();
     if (!c)
         return;
     c->setCompositeOperation(op, blendMode);
 }
 
+void CanvasRenderingContext2D::setCurrentTransform(SVGPropertyTearOff<SVGMatrix>* currentTransform, ExceptionState& es)
+{
+    if (!currentTransform) {
+        es.throwDOMException(TypeError);
+        return;
+    }
+    const SVGMatrix& matrix = currentTransform->propertyReference();
+    setTransform(matrix.a(), matrix.b(), matrix.c(), matrix.d(), matrix.e(), matrix.f());
+}
+
 void CanvasRenderingContext2D::scale(float sx, float sy)
 {
     GraphicsContext* c = drawingContext();
     if (!c)
         return;
     if (!state().m_invertibleCTM)
         return;
 
     if (!std::isfinite(sx) | !std::isfinite(sy))
         return;
@@ skipping 82 matching lines @@
     if (!std::isfinite(m11) | !std::isfinite(m21) | !std::isfinite(dx) | !std::isfinite(m12) | !std::isfinite(m22) | !std::isfinite(dy))
         return;
 
     AffineTransform transform(m11, m12, m21, m22, dx, dy);
     AffineTransform newTransform = state().m_transform * transform;
     if (state().m_transform == newTransform)
         return;
 
     realizeSaves();
 
+    modifiableState().m_transform = newTransform;

[dshwang, 2013/09/20 11:38:52]

when setting non-invertible matrix, currentTransform should keep the value of
non-invertible matrix.

For example,
context.currentTrasform = SVGMatrix(0,0,0,1,0,0);

currentTrasform must be [0,0,0,1,0,0] and the invertible flag of the context
must be set to false.

New layout test covers it.

     if (!newTransform.isInvertible()) {
         modifiableState().m_invertibleCTM = false;
         return;
     }
 
-    modifiableState().m_transform = newTransform;
     c->concatCTM(transform);
     m_path.transform(transform.inverse());
 }
 
 void CanvasRenderingContext2D::resetTransform()
 {
     GraphicsContext* c = drawingContext();
     if (!c)
         return;
 
@@ skipping 1697 matching lines @@
     const int focusRingWidth = 5;
     const int focusRingOutline = 0;
     c->drawFocusRing(path, focusRingWidth, focusRingOutline, focusRingColor);
 
     c->restore();
 
     didDraw(dirtyRect);
 }
 
 } // namespace WebCore