1 files changed, 120 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/GenericScrollAnimation.cpp b/gfx/layers/apz/src/GenericScrollAnimation.cpp
new file mode 100644
index 0000000000..9320482295
--- /dev/null
+++ b/gfx/layers/apz/src/GenericScrollAnimation.cpp
@@ -0,0 +1,120 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set ts=8 sts=2 et sw=2 tw=80: */
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "GenericScrollAnimation.h"
+
+#include "AsyncPanZoomController.h"
+#include "FrameMetrics.h"
+#include "nsPoint.h"
+#include "ScrollAnimationPhysics.h"
+#include "ScrollAnimationBezierPhysics.h"
+#include "ScrollAnimationMSDPhysics.h"
+#include "mozilla/StaticPrefs_general.h"
+
+namespace mozilla {
+namespace layers {
+
+GenericScrollAnimation::GenericScrollAnimation(
+    AsyncPanZoomController& aApzc, const nsPoint& aInitialPosition,
+    const ScrollAnimationBezierPhysicsSettings& aSettings)
+    : mApzc(aApzc), mFinalDestination(aInitialPosition) {
+  // ScrollAnimationBezierPhysics (despite it's name) handles the case of
+  // general.smoothScroll being disabled whereas ScrollAnimationMSDPhysics does
+  // not (ie it scrolls smoothly).
+  if (StaticPrefs::general_smoothScroll() &&
+      StaticPrefs::general_smoothScroll_msdPhysics_enabled()) {
+    mAnimationPhysics = MakeUnique<ScrollAnimationMSDPhysics>(aInitialPosition);
+  } else {
+    mAnimationPhysics =
+        MakeUnique<ScrollAnimationBezierPhysics>(aInitialPosition, aSettings);
+  }
+}
+
+void GenericScrollAnimation::UpdateDelta(TimeStamp aTime, const nsPoint& aDelta,
+                                         const nsSize& aCurrentVelocity) {
+  mFinalDestination += aDelta;
+
+  Update(aTime, aCurrentVelocity);
+}
+
+void GenericScrollAnimation::UpdateDestination(TimeStamp aTime,
+                                               const nsPoint& aDestination,
+                                               const nsSize& aCurrentVelocity) {
+  mFinalDestination = aDestination;
+
+  Update(aTime, aCurrentVelocity);
+}
+
+void GenericScrollAnimation::Update(TimeStamp aTime,
+                                    const nsSize& aCurrentVelocity) {
+  // Clamp the final destination to the scrollable area.
+  CSSPoint clamped = CSSPoint::FromAppUnits(mFinalDestination);
+  clamped.x = mApzc.mX.ClampOriginToScrollableRect(clamped.x);
+  clamped.y = mApzc.mY.ClampOriginToScrollableRect(clamped.y);
+  mFinalDestination = CSSPoint::ToAppUnits(clamped);
+
+  mAnimationPhysics->Update(aTime, mFinalDestination, aCurrentVelocity);
+}
+
+bool GenericScrollAnimation::DoSample(FrameMetrics& aFrameMetrics,
+                                      const TimeDuration& aDelta) {
+  TimeStamp now = mApzc.GetFrameTime().Time();
+  CSSToParentLayerScale zoom(aFrameMetrics.GetZoom());
+  if (zoom == CSSToParentLayerScale(0)) {
+    return false;
+  }
+
+  // If the animation is finished, make sure the final position is correct by
+  // using one last displacement. Otherwise, compute the delta via the timing
+  // function as normal.
+  bool finished = mAnimationPhysics->IsFinished(now);
+  nsPoint sampledDest = mAnimationPhysics->PositionAt(now);
+  ParentLayerPoint displacement = (CSSPoint::FromAppUnits(sampledDest) -
+                                   aFrameMetrics.GetVisualScrollOffset()) *
+                                  zoom;
+
+  if (finished) {
+    mApzc.mX.SetVelocity(0);
+    mApzc.mY.SetVelocity(0);
+  } else if (!IsZero(displacement / zoom)) {
+    // Convert velocity from AppUnits/Seconds to ParentLayerCoords/Milliseconds
+    nsSize velocity = mAnimationPhysics->VelocityAt(now);
+    ParentLayerPoint velocityPL =
+        CSSPoint::FromAppUnits(nsPoint(velocity.width, velocity.height)) * zoom;
+    mApzc.mX.SetVelocity(velocityPL.x / 1000.0);
+    mApzc.mY.SetVelocity(velocityPL.y / 1000.0);
+  }
+  // Note: we ignore overscroll for generic animations.
+  ParentLayerPoint adjustedOffset, overscroll;
+  mApzc.mX.AdjustDisplacement(
+      displacement.x, adjustedOffset.x, overscroll.x,
+      mDirectionForcedToOverscroll == Some(ScrollDirection::eHorizontal));
+  mApzc.mY.AdjustDisplacement(
+      displacement.y, adjustedOffset.y, overscroll.y,
+      mDirectionForcedToOverscroll == Some(ScrollDirection::eVertical));
+  // If we expected to scroll, but there's no more scroll range on either axis,
+  // then end the animation early. Note that the initial displacement could be 0
+  // if the compositor ran very quickly (<1ms) after the animation was created.
+  // When that happens we want to make sure the animation continues.
+  if (!IsZero(displacement / zoom) && IsZero(adjustedOffset / zoom)) {
+    // Nothing more to do - end the animation.
+    return false;
+  }
+  mApzc.ScrollBy(adjustedOffset / zoom);
+  return !finished;
+}
+
+bool GenericScrollAnimation::HandleScrollOffsetUpdate(
+    const Maybe<CSSPoint>& aRelativeDelta) {
+  if (aRelativeDelta) {
+    mAnimationPhysics->ApplyContentShift(*aRelativeDelta);
+    return true;
+  }
+  return false;
+}
+
+}  // namespace layers
+}  // namespace mozilla