Bug 1835600 - Add scroll snap support to SmoothScrollAnimation. r=hiro

And also propagate the ScrollTriggeredByScript flag through it.

Differential Revision: https://phabricator.services.mozilla.com/D181421

gfx/layers/apz/src/AsyncPanZoomController.cpp

@@ -3936,11 +3936,12 @@ void AsyncPanZoomController::HandleSmoothScrollOverscroll(
                         BuildOverscrollHandoffChain(), nullptr);
 }
 
-void AsyncPanZoomController::SmoothScrollTo(const CSSPoint& aDestination,
-                                            const ScrollOrigin& aOrigin) {
+void AsyncPanZoomController::SmoothScrollTo(
+    CSSSnapTarget&& aDestination, ScrollTriggeredByScript aTriggeredByScript,
+    const ScrollOrigin& aOrigin) {
   // Convert velocity from ParentLayerPoints/ms to ParentLayerPoints/s and then
   // to appunits/second.
-  nsPoint destination = CSSPoint::ToAppUnits(aDestination);
+  nsPoint destination = CSSPoint::ToAppUnits(aDestination.mPosition);
   nsSize velocity;
   if (Metrics().GetZoom() != CSSToParentLayerScale(0)) {
     velocity = CSSSize::ToAppUnits(ParentLayerSize(mX.GetVelocity() * 1000.0f,
@@ -3953,8 +3954,9 @@ void AsyncPanZoomController::SmoothScrollTo(const CSSPoint& aDestination,
         mAnimation->AsSmoothScrollAnimation());
     if (animation->GetScrollOrigin() == aOrigin) {
       APZC_LOG("%p updating destination on existing animation\n", this);
-      animation->UpdateDestination(GetFrameTime().Time(), destination,
-                                   velocity);
+      animation->UpdateDestinationAndSnapTargets(
+          GetFrameTime().Time(), destination, velocity,
+          std::move(aDestination.mTargetIds), aTriggeredByScript);
       return;
     }
   }
@@ -3965,7 +3967,9 @@ void AsyncPanZoomController::SmoothScrollTo(const CSSPoint& aDestination,
       CSSPoint::ToAppUnits(Metrics().GetVisualScrollOffset());
   RefPtr<SmoothScrollAnimation> animation =
       new SmoothScrollAnimation(*this, initialPosition, aOrigin);
-  animation->UpdateDestination(GetFrameTime().Time(), destination, velocity);
+  animation->UpdateDestinationAndSnapTargets(
+      GetFrameTime().Time(), destination, velocity,
+      std::move(aDestination.mTargetIds), aTriggeredByScript);
   StartAnimation(animation.get());
 }
 
@@ -4690,6 +4694,10 @@ bool AsyncPanZoomController::UpdateAnimation(
           mLastSnapTargetIds =
               mAnimation->AsSmoothMsdScrollAnimation()->TakeSnapTargetIds();
         }
+      } else if (mAnimation->AsSmoothScrollAnimation()) {
+        RecursiveMutexAutoLock lock(mRecursiveMutex);
+        mLastSnapTargetIds =
+            mAnimation->AsSmoothScrollAnimation()->TakeSnapTargetIds();
       }
       mAnimation = nullptr;
     }
@@ -5518,10 +5526,10 @@ void AsyncPanZoomController::NotifyLayersUpdated(
             scrollUpdate.GetScrollTriggeredByScript());
       } else {
         MOZ_ASSERT(scrollUpdate.GetMode() == ScrollMode::Smooth);
-        MOZ_ASSERT(!scrollUpdate.WasTriggeredByScript());
-        MOZ_ASSERT(scrollUpdate.GetSnapTargetIds().mIdsOnX.IsEmpty());
-        MOZ_ASSERT(scrollUpdate.GetSnapTargetIds().mIdsOnY.IsEmpty());
-        SmoothScrollTo(destination, scrollUpdate.GetOrigin());
+        SmoothScrollTo(
+            CSSSnapTarget{destination, scrollUpdate.GetSnapTargetIds()},
+            scrollUpdate.GetScrollTriggeredByScript(),
+            scrollUpdate.GetOrigin());
       }
       continue;
     }

gfx/layers/apz/src/AsyncPanZoomController.h

@@ -1583,7 +1583,8 @@ class AsyncPanZoomController {
 
   // Start a smooth-scrolling animation to the given destination, with physics
   // based on the prefs for the indicated origin.
-  void SmoothScrollTo(const CSSPoint& aDestination,
+  void SmoothScrollTo(CSSSnapTarget&& aDestination,
+                      ScrollTriggeredByScript aTriggeredByScript,
                       const ScrollOrigin& aOrigin);
 
   // Start a smooth-scrolling animation to the given destination, with MSD

gfx/layers/apz/src/SmoothScrollAnimation.cpp

@@ -6,6 +6,8 @@
 
 #include "SmoothScrollAnimation.h"
 #include "ScrollAnimationBezierPhysics.h"
+#include "ScrollPositionUpdate.h"
+#include "apz/src/GenericScrollAnimation.h"
 #include "mozilla/layers/APZPublicUtils.h"
 
 namespace mozilla {
@@ -17,12 +19,23 @@ SmoothScrollAnimation::SmoothScrollAnimation(AsyncPanZoomController& aApzc,
     : GenericScrollAnimation(
           aApzc, aInitialPosition,
           apz::ComputeBezierAnimationSettingsForOrigin(aOrigin)),
-      mOrigin(aOrigin) {}
+      mOrigin(aOrigin),
+      mTriggeredByScript(ScrollTriggeredByScript::No) {}
 
 SmoothScrollAnimation* SmoothScrollAnimation::AsSmoothScrollAnimation() {
   return this;
 }
 
+void SmoothScrollAnimation::UpdateDestinationAndSnapTargets(
+    TimeStamp aTime, const nsPoint& aDestination,
+    const nsSize& aCurrentVelocity, ScrollSnapTargetIds&& aSnapTargetIds,
+    ScrollTriggeredByScript aTriggeredByScript) {
+  GenericScrollAnimation::UpdateDestination(aTime, aDestination,
+                                            aCurrentVelocity);
+  mSnapTargetIds = std::move(aSnapTargetIds);
+  mTriggeredByScript = aTriggeredByScript;
+}
+
 ScrollOrigin SmoothScrollAnimation::GetScrollOrigin() const { return mOrigin; }
 
 ScrollOrigin SmoothScrollAnimation::GetScrollOriginForAction(

gfx/layers/apz/src/SmoothScrollAnimation.h

@@ -8,6 +8,7 @@
 #define mozilla_layers_SmoothScrollAnimation_h_
 
 #include "GenericScrollAnimation.h"
+#include "ScrollPositionUpdate.h"
 #include "mozilla/ScrollOrigin.h"
 #include "mozilla/layers/KeyboardScrollAction.h"
 
@@ -19,16 +20,26 @@ class AsyncPanZoomController;
 class SmoothScrollAnimation : public GenericScrollAnimation {
  public:
   SmoothScrollAnimation(AsyncPanZoomController& aApzc,
-                        const nsPoint& aInitialPosition,
-                        ScrollOrigin aScrollOrigin);
+                        const nsPoint& aInitialPosition, ScrollOrigin aOrigin);
+
+  void UpdateDestinationAndSnapTargets(
+      TimeStamp aTime, const nsPoint& aDestination,
+      const nsSize& aCurrentVelocity, ScrollSnapTargetIds&& aSnapTargetIds,
+      ScrollTriggeredByScript aTriggeredByScript);
 
   SmoothScrollAnimation* AsSmoothScrollAnimation() override;
+  bool WasTriggeredByScript() const override {
+    return mTriggeredByScript == ScrollTriggeredByScript::Yes;
+  }
+  ScrollSnapTargetIds TakeSnapTargetIds() { return std::move(mSnapTargetIds); }
   ScrollOrigin GetScrollOrigin() const;
   static ScrollOrigin GetScrollOriginForAction(
       KeyboardScrollAction::KeyboardScrollActionType aAction);
 
  private:
   ScrollOrigin mOrigin;
+  ScrollSnapTargetIds mSnapTargetIds;
+  ScrollTriggeredByScript mTriggeredByScript;
 };
 
 }  // namespace layers

layout/generic/nsGfxScrollFrame.cpp

@@ -2560,14 +2560,6 @@ void nsHTMLScrollFrame::ScrollToWithOrigin(nsPoint aScrollPosition,
       aParams.IsSmooth() && nsLayoutUtils::IsSmoothScrollingEnabled();
   if (!mAsyncScroll) {
     if (isSmoothScroll && canHandoffToApz) {
-      // APZ does not handle ScrollTriggeredByScript::Yes and snapTargetIds for
-      // ScrollMode::Smooth (but this can be added if the assertion firing
-      // indicates it's necessary).
-      MOZ_ASSERT(aParams.mTriggeredByScript == ScrollTriggeredByScript::No);
-      if (snapTargetIds) {
-        MOZ_ASSERT(snapTargetIds->mIdsOnX.IsEmpty());
-        MOZ_ASSERT(snapTargetIds->mIdsOnY.IsEmpty());
-      }
       ApzSmoothScrollTo(mDestination, ScrollMode::Smooth, aParams.mOrigin,
                         aParams.mTriggeredByScript, std::move(snapTargetIds));
       return;