From a7d2fa0411a5a8a571ac52114756c25d5c98b165 Mon Sep 17 00:00:00 2001
From: Brian Birtles <birtles@gmail.com>
Date: Wed, 26 Apr 2017 13:00:11 +0900
Subject: [PATCH] Bug 1355348 - Add SMIL restyles in the stylo pretraverse;
 r=heycam

MozReview-Commit-ID: mwjkKr6wsr

--HG--
extra : rebase_source : 23324e128041f6d190312958dab093da382863f3
---
 dom/smil/nsSMILAnimationController.cpp | 63 ++++++++++++++++++++++++++
 dom/smil/nsSMILAnimationController.h   |  4 ++
 layout/style/ServoStyleSet.cpp         | 14 ++++++
 3 files changed, 81 insertions(+)

diff --git a/dom/smil/nsSMILAnimationController.cpp b/dom/smil/nsSMILAnimationController.cpp
index 590b84877cfe..61ed29eb50a5 100644
--- a/dom/smil/nsSMILAnimationController.cpp
+++ b/dom/smil/nsSMILAnimationController.cpp
@@ -11,6 +11,8 @@
 #include "mozilla/AutoRestore.h"
 #include "mozilla/dom/Element.h"
 #include "mozilla/dom/SVGAnimationElement.h"
+#include "mozilla/RestyleManagerInlines.h"
+#include "nsContentUtils.h"
 #include "nsCSSProps.h"
 #include "nsIDocument.h"
 #include "nsIPresShell.h"
@@ -723,6 +725,67 @@ nsSMILAnimationController::AddStyleUpdatesTo(RestyleTracker& aTracker)
   mMightHavePendingStyleUpdates = false;
 }
 
+bool
+nsSMILAnimationController::PreTraverse()
+{
+  return PreTraverseInSubtree(nullptr);
+}
+
+bool
+nsSMILAnimationController::PreTraverseInSubtree(Element* aRoot)
+{
+  MOZ_ASSERT(NS_IsMainThread());
+
+  if (!mMightHavePendingStyleUpdates) {
+    return false;
+  }
+
+  nsIPresShell* shell = mDocument->GetShell();
+  if (!shell) {
+    return false;
+  }
+
+  nsPresContext* context = shell->GetPresContext();
+  if (!context) {
+    return false;
+  }
+  MOZ_ASSERT(context->RestyleManager()->IsServo(),
+             "PreTraverse should only be called for the servo style system");
+
+  bool foundElementsNeedingRestyle = false;
+  for (auto iter = mAnimationElementTable.Iter(); !iter.Done(); iter.Next()) {
+    SVGAnimationElement* animElement = iter.Get()->GetKey();
+
+    nsSMILTargetIdentifier key;
+    if (!GetTargetIdentifierForAnimation(animElement, key)) {
+      // Something's wrong/missing about animation's target; skip this animation
+      continue;
+    }
+
+    // Ignore restyles that aren't in the flattened tree subtree rooted at
+    // aRoot.
+    if (aRoot &&
+        !nsContentUtils::ContentIsFlattenedTreeDescendantOf(key.mElement,
+                                                            aRoot)) {
+      continue;
+    }
+
+    context->RestyleManager()->AsServo()->
+      PostRestyleEventForAnimations(key.mElement,
+                                    eRestyle_StyleAttribute_Animations);
+
+    foundElementsNeedingRestyle = true;
+  }
+
+  // Only clear the mMightHavePendingStyleUpdates flag if we definitely posted
+  // all restyles.
+  if (!aRoot) {
+    mMightHavePendingStyleUpdates = false;
+  }
+
+  return foundElementsNeedingRestyle;
+}
+
 //----------------------------------------------------------------------
 // Add/remove child time containers
 
diff --git a/dom/smil/nsSMILAnimationController.h b/dom/smil/nsSMILAnimationController.h
index 9c565b78b394..b880575966e5 100644
--- a/dom/smil/nsSMILAnimationController.h
+++ b/dom/smil/nsSMILAnimationController.h
@@ -25,6 +25,7 @@ class nsIDocument;
 namespace mozilla {
 class RestyleTracker;
 namespace dom {
+class Element;
 class SVGAnimationElement;
 } // namespace dom
 } // namespace mozilla
@@ -113,6 +114,9 @@ public:
     return mMightHavePendingStyleUpdates;
   }
 
+  bool PreTraverse();
+  bool PreTraverseInSubtree(mozilla::dom::Element* aRoot);
+
 protected:
   ~nsSMILAnimationController();
 
diff --git a/layout/style/ServoStyleSet.cpp b/layout/style/ServoStyleSet.cpp
index 899477dc789b..fc2f55b3ec3f 100644
--- a/layout/style/ServoStyleSet.cpp
+++ b/layout/style/ServoStyleSet.cpp
@@ -21,6 +21,7 @@
 #include "nsHTMLStyleSheet.h"
 #include "nsIDocumentInlines.h"
 #include "nsPrintfCString.h"
+#include "nsSMILAnimationController.h"
 #include "nsStyleContext.h"
 #include "nsStyleSet.h"
 
@@ -263,10 +264,18 @@ ServoStyleSet::PreTraverse(Element* aRoot)
 
   // Process animation stuff that we should avoid doing during the parallel
   // traversal.
+  nsSMILAnimationController* smilController =
+    mPresContext->Document()->GetAnimationController();
   if (aRoot) {
     mPresContext->EffectCompositor()->PreTraverseInSubtree(aRoot);
+    if (smilController) {
+      smilController->PreTraverseInSubtree(aRoot);
+    }
   } else {
     mPresContext->EffectCompositor()->PreTraverse();
+    if (smilController) {
+      smilController->PreTraverse();
+    }
   }
 }
 
@@ -295,6 +304,11 @@ ServoStyleSet::PrepareAndTraverseSubtree(RawGeckoElementBorrowed aRoot,
 
   // If there are still animation restyles needed, trigger a second traversal to
   // update CSS animations or transitions' styles.
+  //
+  // We don't need to do this for SMIL since SMIL only updates its animation
+  // values once at the begin of a tick. As a result, even if the previous
+  // traversal caused, for example, the font-size to change, the SMIL style
+  // won't be updated until the next tick anyway.
   EffectCompositor* compositor = mPresContext->EffectCompositor();
   if (forReconstruct ? compositor->PreTraverseInSubtree(root)
                      : compositor->PreTraverse()) {