Bug 653571 - Add IsIdentity() function to SVG{Length,Point}ListAndInfo. r=dholbert

content/svg/content/src/SVGLengthList.h

@@ -196,6 +196,19 @@ public:
     return static_cast<nsSVGElement*>(e.get());
   }
 
+  /**
+   * Returns true if this object is an "identity" value, from the perspective
+   * of SMIL. In other words, returns true until the initial value set up in
+   * SVGLengthListSMILType::Init() has been changed with a SetInfo() call.
+   */
+  bool IsIdentity() const {
+    if (!mElement) {
+      NS_ABORT_IF_FALSE(IsEmpty(), "target element propagation failure");
+      return true;
+    }
+    return false;
+  }
+
   uint8_t Axis() const {
     NS_ABORT_IF_FALSE(mElement, "Axis() isn't valid");
     return mAxis;

content/svg/content/src/SVGLengthListSMILType.cpp

@@ -93,15 +93,11 @@ SVGLengthListSMILType::Add(nsSMILValue& aDest,
   // should be, not zeros, and those values are not explicit or otherwise
   // available.
 
-  if (!valueToAdd.Element()) { // Adding identity value - no-op
-    NS_ABORT_IF_FALSE(valueToAdd.IsEmpty(),
-                      "Identity values should be empty");
+  if (valueToAdd.IsIdentity()) { // Adding identity value - no-op
     return NS_OK;
   }
 
-  if (!dest.Element()) { // Adding *to* an identity value
-    NS_ABORT_IF_FALSE(dest.IsEmpty(),
-                      "Identity values should be empty");
+  if (dest.IsIdentity()) { // Adding *to* an identity value
     if (!dest.SetLength(valueToAdd.Length())) {
       return NS_ERROR_OUT_OF_MEMORY;
     }

content/svg/content/src/SVGPathData.h

@@ -253,6 +253,11 @@ public:
     return SVGPathData::CopyFrom(rhs);
   }
 
+  /**
+   * Returns true if this object is an "identity" value, from the perspective
+   * of SMIL. In other words, returns true until the initial value set up in
+   * SVGPathSegListSMILType::Init() has been changed with a SetInfo() call.
+   */
   bool IsIdentity() const {
     if (!mElement) {
       NS_ABORT_IF_FALSE(IsEmpty(), "target element propagation failure");

content/svg/content/src/SVGPointList.h

@@ -174,6 +174,19 @@ public:
     return static_cast<nsSVGElement*>(e.get());
   }
 
+  /**
+   * Returns true if this object is an "identity" value, from the perspective
+   * of SMIL. In other words, returns true until the initial value set up in
+   * SVGPointListSMILType::Init() has been changed with a SetInfo() call.
+   */
+  bool IsIdentity() const {
+    if (!mElement) {
+      NS_ABORT_IF_FALSE(IsEmpty(), "target element propagation failure");
+      return true;
+    } 
+    return false;
+  }
+
   nsresult CopyFrom(const SVGPointListAndInfo& rhs) {
     mElement = rhs.mElement;
     return SVGPointList::CopyFrom(rhs);

content/svg/content/src/SVGPointListSMILType.cpp

@@ -78,14 +78,10 @@ SVGPointListSMILType::Add(nsSMILValue& aDest,
   NS_ABORT_IF_FALSE(dest.Element() || valueToAdd.Element(),
                     "Target element propagation failure");
 
-  if (!valueToAdd.Element()) {
-    NS_ABORT_IF_FALSE(valueToAdd.Length() == 0,
-                      "Not identity value - target element propagation failure");
+  if (valueToAdd.IsIdentity()) {
     return NS_OK;
   }
-  if (!dest.Element()) {
-    NS_ABORT_IF_FALSE(dest.Length() == 0,
-                      "Not identity value - target element propagation failure");
+  if (dest.IsIdentity()) {
     if (!dest.SetLength(valueToAdd.Length())) {
       return NS_ERROR_OUT_OF_MEMORY;
     }