Bug 1241575 - Use transform property syntax to parse WebKitCSSMatrix transform list. r=heycam

dom/base/WebKitCSSMatrix.cpp

@@ -8,6 +8,8 @@
 
 #include "mozilla/dom/BindingUtils.h"
 #include "mozilla/dom/WebKitCSSMatrixBinding.h"
+#include "nsCSSParser.h"
+#include "nsStyleTransformMatrix.h"
 
 namespace mozilla {
 namespace dom {
@@ -56,11 +58,58 @@ WebKitCSSMatrix*
 WebKitCSSMatrix::SetMatrixValue(const nsAString& aTransformList,
                                 ErrorResult& aRv)
 {
-  DOMMatrix::SetMatrixValue(aTransformList, aRv);
-  if (NS_WARN_IF(aRv.Failed())) {
+  // An empty string is a no-op.
+  if (aTransformList.IsEmpty()) {
+    return this;
+  }
+
+  nsCSSValue value;
+  nsCSSParser parser;
+  bool parseSuccess = parser.ParseTransformProperty(aTransformList,
+                                                    true,
+                                                    value);
+  if (!parseSuccess) {
+    aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
     return nullptr;
   }
 
+  // A value of "none" results in a 2D identity matrix.
+  if (value.GetUnit() == eCSSUnit_None) {
+    mMatrix3D = nullptr;
+    mMatrix2D = new gfx::Matrix();
+    return this;
+  }
+
+  // A value other than a transform-list is a syntax error.
+  if (value.GetUnit() != eCSSUnit_SharedList) {
+    aRv.Throw(NS_ERROR_DOM_SYNTAX_ERR);
+    return nullptr;
+  }
+
+  RuleNodeCacheConditions dummy;
+  nsStyleTransformMatrix::TransformReferenceBox dummyBox;
+  bool contains3dTransform = false;
+  gfx::Matrix4x4 transform = nsStyleTransformMatrix::ReadTransforms(
+                               value.GetSharedListValue()->mHead,
+                               nullptr, nullptr, dummy, dummyBox,
+                               nsPresContext::AppUnitsPerCSSPixel(),
+                               &contains3dTransform);
+
+  if (!contains3dTransform) {
+    mMatrix3D = nullptr;
+    mMatrix2D = new gfx::Matrix();
+
+    SetA(transform._11);
+    SetB(transform._12);
+    SetC(transform._21);
+    SetD(transform._22);
+    SetE(transform._41);
+    SetF(transform._42);
+  } else {
+    mMatrix3D = new gfx::Matrix4x4(transform);
+    mMatrix2D = nullptr;
+  }
+
   return this;
 }