1 files changed, 119 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/WheelScrollAnimation.cpp b/gfx/layers/apz/src/WheelScrollAnimation.cpp
new file mode 100644
index 000000000..d7cb338e6
--- /dev/null
+++ b/gfx/layers/apz/src/WheelScrollAnimation.cpp
@@ -0,0 +1,119 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et 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 "WheelScrollAnimation.h"
+
+#include "AsyncPanZoomController.h"
+#include "gfxPrefs.h"
+#include "nsPoint.h"
+
+namespace mozilla {
+namespace layers {
+
+WheelScrollAnimation::WheelScrollAnimation(AsyncPanZoomController& aApzc,
+                                           const nsPoint& aInitialPosition,
+                                           ScrollWheelInput::ScrollDeltaType aDeltaType)
+  : AsyncScrollBase(aInitialPosition)
+  , mApzc(aApzc)
+  , mFinalDestination(aInitialPosition)
+  , mDeltaType(aDeltaType)
+{
+}
+
+void
+WheelScrollAnimation::Update(TimeStamp aTime, nsPoint aDelta, const nsSize& aCurrentVelocity)
+{
+  InitPreferences(aTime);
+
+  mFinalDestination += aDelta;
+
+  // 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);
+
+  AsyncScrollBase::Update(aTime, mFinalDestination, aCurrentVelocity);
+}
+
+bool
+WheelScrollAnimation::DoSample(FrameMetrics& aFrameMetrics, const TimeDuration& aDelta)
+{
+  TimeStamp now = mApzc.GetFrameTime();
+  CSSToParentLayerScale2D zoom = aFrameMetrics.GetZoom();
+
+  // 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 = IsFinished(now);
+  nsPoint sampledDest = finished
+                        ? mDestination
+                        : PositionAt(now);
+  ParentLayerPoint displacement =
+    (CSSPoint::FromAppUnits(sampledDest) - aFrameMetrics.GetScrollOffset()) * zoom;
+
+  if (finished) {
+    mApzc.mX.SetVelocity(0);
+    mApzc.mY.SetVelocity(0);
+  } else if (!IsZero(displacement)) {
+    // Velocity is measured in ParentLayerCoords / Milliseconds
+    float xVelocity = displacement.x / aDelta.ToMilliseconds();
+    float yVelocity = displacement.y / aDelta.ToMilliseconds();
+    mApzc.mX.SetVelocity(xVelocity);
+    mApzc.mY.SetVelocity(yVelocity);
+  }
+
+  // Note: we ignore overscroll for wheel animations.
+  ParentLayerPoint adjustedOffset, overscroll;
+  mApzc.mX.AdjustDisplacement(displacement.x, adjustedOffset.x, overscroll.x);
+  mApzc.mY.AdjustDisplacement(displacement.y, adjustedOffset.y, overscroll.y,
+                              !mApzc.mScrollMetadata.AllowVerticalScrollWithWheel());
+
+  // 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) && IsZero(adjustedOffset)) {
+    // Nothing more to do - end the animation.
+    return false;
+  }
+
+  aFrameMetrics.ScrollBy(adjustedOffset / zoom);
+  return !finished;
+}
+
+void
+WheelScrollAnimation::InitPreferences(TimeStamp aTime)
+{
+  if (!mIsFirstIteration) {
+    return;
+  }
+
+  switch (mDeltaType) {
+  case ScrollWheelInput::SCROLLDELTA_PAGE:
+    mOriginMaxMS = clamped(gfxPrefs::PageSmoothScrollMaxDurationMs(), 0, 10000);
+    mOriginMinMS = clamped(gfxPrefs::PageSmoothScrollMinDurationMs(), 0, mOriginMaxMS);
+    break;
+  case ScrollWheelInput::SCROLLDELTA_PIXEL:
+    mOriginMaxMS = clamped(gfxPrefs::PixelSmoothScrollMaxDurationMs(), 0, 10000);
+    mOriginMinMS = clamped(gfxPrefs::PixelSmoothScrollMinDurationMs(), 0, mOriginMaxMS);
+    break;
+  case ScrollWheelInput::SCROLLDELTA_LINE:
+  default:
+    mOriginMaxMS = clamped(gfxPrefs::WheelSmoothScrollMaxDurationMs(), 0, 10000);
+    mOriginMinMS = clamped(gfxPrefs::WheelSmoothScrollMinDurationMs(), 0, mOriginMaxMS);
+    break;
+  }
+
+  // The pref is 100-based int percentage, while mIntervalRatio is 1-based ratio
+  mIntervalRatio = ((double)gfxPrefs::SmoothScrollDurationToIntervalRatio()) / 100.0;
+  mIntervalRatio = std::max(1.0, mIntervalRatio);
+
+  InitializeHistory(aTime);
+}
+
+} // namespace layers
+} // namespace mozilla