Bug 1241784 - Part 1: Add a helper function for Element.animate(). r=birtles

Therefore, CSSPseudoElement.animate() can also use it.

dom/base/Element.cpp

@@ -137,13 +137,15 @@
 #include "nsITextControlElement.h"
 #include "nsITextControlFrame.h"
 #include "nsISupportsImpl.h"
+#include "mozilla/dom/CSSPseudoElement.h"
 #include "mozilla/dom/DocumentFragment.h"
-#include "mozilla/IntegerPrintfMacros.h"
+#include "mozilla/dom/KeyframeEffectBinding.h"
 #include "mozilla/dom/WindowBinding.h"
 #include "mozilla/dom/ElementBinding.h"
 #include "mozilla/dom/VRDevice.h"
-#include "nsComputedDOMStyle.h"
+#include "mozilla/IntegerPrintfMacros.h"
 #include "mozilla/Preferences.h"
+#include "nsComputedDOMStyle.h"
 
 using namespace mozilla;
 using namespace mozilla::dom;
@@ -3307,7 +3309,31 @@ Element::Animate(JSContext* aContext,
                  const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
                  ErrorResult& aError)
 {
-  nsCOMPtr<nsIGlobalObject> ownerGlobal = GetOwnerGlobal();
+  Nullable<ElementOrCSSPseudoElement> target;
+  target.SetValue().SetAsElement() = this;
+  return Animate(target, aContext, aFrames, aOptions, aError);
+}
+
+/* static */ already_AddRefed<Animation>
+Element::Animate(const Nullable<ElementOrCSSPseudoElement>& aTarget,
+                 JSContext* aContext,
+                 JS::Handle<JSObject*> aFrames,
+                 const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
+                 ErrorResult& aError)
+{
+  MOZ_ASSERT(!aTarget.IsNull() &&
+             (aTarget.Value().IsElement() ||
+              aTarget.Value().IsCSSPseudoElement()),
+             "aTarget should be initialized");
+
+  RefPtr<Element> referenceElement;
+  if (aTarget.Value().IsElement()) {
+    referenceElement = &aTarget.Value().GetAsElement();
+  } else {
+    referenceElement = aTarget.Value().GetAsCSSPseudoElement().ParentElement();
+  }
+
+  nsCOMPtr<nsIGlobalObject> ownerGlobal = referenceElement->GetOwnerGlobal();
   if (!ownerGlobal) {
     aError.Throw(NS_ERROR_FAILURE);
     return nullptr;
@@ -3327,17 +3353,16 @@ Element::Animate(JSContext* aContext,
     }
   }
 
-  Nullable<ElementOrCSSPseudoElement> target;
-  target.SetValue().SetAsElement() = this;
   RefPtr<KeyframeEffect> effect =
-    KeyframeEffect::Constructor(global, target, frames,
-      TimingParams::FromOptionsUnion(aOptions, target), aError);
+    KeyframeEffect::Constructor(global, aTarget, frames,
+      TimingParams::FromOptionsUnion(aOptions, aTarget), aError);
   if (aError.Failed()) {
     return nullptr;
   }
 
   RefPtr<Animation> animation =
-    Animation::Constructor(global, effect, OwnerDoc()->Timeline(), aError);
+    Animation::Constructor(global, effect,
+                           referenceElement->OwnerDoc()->Timeline(), aError);
   if (aError.Failed()) {
     return nullptr;
   }

dom/base/Element.h

@@ -36,6 +36,7 @@
 #include "mozilla/dom/BindingDeclarations.h"
 #include "mozilla/dom/WindowBinding.h"
 #include "mozilla/dom/ElementBinding.h"
+#include "mozilla/dom/Nullable.h"
 #include "Units.h"
 
 class nsIFrame;
@@ -56,6 +57,7 @@ namespace mozilla {
 namespace dom {
   struct ScrollIntoViewOptions;
   struct ScrollToOptions;
+  class ElementOrCSSPseudoElement;
   class UnrestrictedDoubleOrKeyframeAnimationOptions;
 } // namespace dom
 } // namespace mozilla
@@ -826,11 +828,20 @@ public:
   {
   }
 
-  already_AddRefed<Animation> Animate(
-    JSContext* aContext,
-    JS::Handle<JSObject*> aFrames,
-    const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
-    ErrorResult& aError);
+  already_AddRefed<Animation>
+  Animate(JSContext* aContext,
+          JS::Handle<JSObject*> aFrames,
+          const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
+          ErrorResult& aError);
+
+  // A helper method that factors out the common functionality needed by
+  // Element::Animate and CSSPseudoElement::Animate
+  static already_AddRefed<Animation>
+  Animate(const Nullable<ElementOrCSSPseudoElement>& aTarget,
+          JSContext* aContext,
+          JS::Handle<JSObject*> aFrames,
+          const UnrestrictedDoubleOrKeyframeAnimationOptions& aOptions,
+          ErrorResult& aError);
 
   // Note: GetAnimations will flush style while GetAnimationsUnsorted won't.
   void GetAnimations(nsTArray<RefPtr<Animation>>& aAnimations);