Bug 1667018 - minor improvements to path code r=emilio

- Use IsMoveto method where appropriate
- Avoid referencing path in animation so we can move to supporting shapes later

Differential Revision: https://phabricator.services.mozilla.com/D91242

dom/svg/SVGMotionSMILAnimationFunction.cpp

@@ -211,16 +211,13 @@ void SVGMotionSMILAnimationFunction::RebuildPathAndVerticesFromMpathElem(
 
   // Use the path that's the target of our chosen <mpath> child.
   SVGPathElement* pathElem = aMpathElem->GetReferencedPath();
-  if (pathElem) {
-    const SVGPathData& path = pathElem->GetAnimPathSegList()->GetAnimValue();
-    // Path data must contain of at least one path segment (if the path data
-    // doesn't begin with a valid "M", then it's invalid).
-    if (path.Length()) {
-      bool ok =
-          path.GetDistancesFromOriginToEndsOfVisibleSegments(&mPathVertices);
-      if (ok && mPathVertices.Length()) {
-        mPath = pathElem->GetOrBuildPathForMeasuring();
-      }
+  // Path data must contain of at least one path segment (if the path data
+  // doesn't begin with a valid "M", then it's invalid).
+  if (pathElem && pathElem->HasValidDimensions()) {
+    bool ok =
+        pathElem->GetDistancesFromOriginToEndsOfVisibleSegments(&mPathVertices);
+    if (ok && mPathVertices.Length()) {
+      mPath = pathElem->GetOrBuildPathForMeasuring();
     }
   }
 }

dom/svg/SVGPathData.cpp

@@ -162,8 +162,7 @@ bool SVGPathData::GetDistancesFromOriginToEndsOfVisibleSegments(
     // this case an equal amount of time is spent on each path segment,
     // except on moveto segments which are jumped over immediately.
 
-    if (i == 0 ||
-        (segType != PATHSEG_MOVETO_ABS && segType != PATHSEG_MOVETO_REL)) {
+    if (i == 0 || !IsMoveto(segType)) {
       if (!aOutput->AppendElement(state.length, fallible)) {
         return false;
       }
@@ -480,8 +479,7 @@ already_AddRefed<Path> SVGPathData::BuildPath(PathBuilder* aBuilder,
                          // seg anyway
     }
 
-    subpathContainsNonMoveTo =
-        segType != PATHSEG_MOVETO_ABS && segType != PATHSEG_MOVETO_REL;
+    subpathContainsNonMoveTo = !IsMoveto(segType);
     i += argCount;
     prevSegType = segType;
     segStart = segEnd;

dom/svg/SVGPathElement.h

@@ -55,6 +55,12 @@ class SVGPathElement final : public SVGPathElementBase {
    */
   virtual already_AddRefed<Path> GetOrBuildPathForMeasuring() override;
 
+  bool GetDistancesFromOriginToEndsOfVisibleSegments(
+      FallibleTArray<double>* aOutput) const {
+    return mD.GetAnimValue().GetDistancesFromOriginToEndsOfVisibleSegments(
+        aOutput);
+  }
+
   // nsIContent interface
   virtual nsresult Clone(dom::NodeInfo*, nsINode** aResult) const override;