1 files changed, 201 insertions, 0 deletions
diff --git a/widget/cocoa/SwipeTracker.mm b/widget/cocoa/SwipeTracker.mm
new file mode 100644
index 0000000000..50c9579200
--- /dev/null
+++ b/widget/cocoa/SwipeTracker.mm
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+/* -*- 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 "SwipeTracker.h"
+
+#include "InputData.h"
+#include "mozilla/FlushType.h"
+#include "mozilla/PresShell.h"
+#include "mozilla/TimeStamp.h"
+#include "mozilla/TouchEvents.h"
+#include "mozilla/dom/SimpleGestureEventBinding.h"
+#include "nsAlgorithm.h"
+#include "nsChildView.h"
+#include "nsRefreshDriver.h"
+#include "UnitTransforms.h"
+
+// These values were tweaked to make the physics feel similar to the native swipe.
+static const double kSpringForce = 250.0;
+static const double kVelocityTwitchTolerance = 0.0000001;
+static const double kWholePagePixelSize = 1000.0;
+static const double kRubberBandResistanceFactor = 4.0;
+static const double kSwipeSuccessThreshold = 0.25;
+static const double kSwipeSuccessVelocityContribution = 0.3;
+
+namespace mozilla {
+
+static already_AddRefed<nsRefreshDriver> GetRefreshDriver(nsIWidget& aWidget) {
+  nsIWidgetListener* widgetListener = aWidget.GetWidgetListener();
+  PresShell* presShell = widgetListener ? widgetListener->GetPresShell() : nullptr;
+  nsPresContext* presContext = presShell ? presShell->GetPresContext() : nullptr;
+  RefPtr<nsRefreshDriver> refreshDriver = presContext ? presContext->RefreshDriver() : nullptr;
+  return refreshDriver.forget();
+}
+
+SwipeTracker::SwipeTracker(nsChildView& aWidget, const PanGestureInput& aSwipeStartEvent,
+                           uint32_t aAllowedDirections, uint32_t aSwipeDirection)
+    : mWidget(aWidget),
+      mRefreshDriver(GetRefreshDriver(mWidget)),
+      mAxis(0.0, 0.0, 0.0, kSpringForce, 1.0),
+      mEventPosition(RoundedToInt(ViewAs<LayoutDevicePixel>(
+          aSwipeStartEvent.mPanStartPoint,
+          PixelCastJustification::LayoutDeviceIsScreenForUntransformedEvent))),
+      mLastEventTimeStamp(aSwipeStartEvent.mTimeStamp),
+      mAllowedDirections(aAllowedDirections),
+      mSwipeDirection(aSwipeDirection),
+      mGestureAmount(0.0),
+      mCurrentVelocity(0.0),
+      mEventsAreControllingSwipe(true),
+      mEventsHaveStartedNewGesture(false),
+      mRegisteredWithRefreshDriver(false) {
+  SendSwipeEvent(eSwipeGestureStart, 0, 0.0, aSwipeStartEvent.mTimeStamp);
+  ProcessEvent(aSwipeStartEvent);
+}
+
+void SwipeTracker::Destroy() { UnregisterFromRefreshDriver(); }
+
+SwipeTracker::~SwipeTracker() {
+  MOZ_ASSERT(!mRegisteredWithRefreshDriver, "Destroy needs to be called before deallocating");
+}
+
+double SwipeTracker::SwipeSuccessTargetValue() const {
+  return (mSwipeDirection == dom::SimpleGestureEvent_Binding::DIRECTION_RIGHT) ? -1.0 : 1.0;
+}
+
+double SwipeTracker::ClampToAllowedRange(double aGestureAmount) const {
+  // gestureAmount needs to stay between -1 and 0 when swiping right and
+  // between 0 and 1 when swiping left.
+  double min = (mSwipeDirection == dom::SimpleGestureEvent_Binding::DIRECTION_RIGHT) ? -1.0 : 0.0;
+  double max = (mSwipeDirection == dom::SimpleGestureEvent_Binding::DIRECTION_LEFT) ? 1.0 : 0.0;
+  return clamped(aGestureAmount, min, max);
+}
+
+bool SwipeTracker::ComputeSwipeSuccess() const {
+  double targetValue = SwipeSuccessTargetValue();
+
+  // If the fingers were moving away from the target direction when they were
+  // lifted from the touchpad, abort the swipe.
+  if (mCurrentVelocity * targetValue < -kVelocityTwitchTolerance) {
+    return false;
+  }
+
+  return (mGestureAmount * targetValue +
+          mCurrentVelocity * targetValue * kSwipeSuccessVelocityContribution) >=
+         kSwipeSuccessThreshold;
+}
+
+nsEventStatus SwipeTracker::ProcessEvent(const PanGestureInput& aEvent) {
+  // If the fingers have already been lifted, don't process this event for swiping.
+  if (!mEventsAreControllingSwipe) {
+    // Return nsEventStatus_eConsumeNoDefault for events from the swipe gesture
+    // and nsEventStatus_eIgnore for events of subsequent scroll gestures.
+    if (aEvent.mType == PanGestureInput::PANGESTURE_MAYSTART ||
+        aEvent.mType == PanGestureInput::PANGESTURE_START) {
+      mEventsHaveStartedNewGesture = true;
+    }
+    return mEventsHaveStartedNewGesture ? nsEventStatus_eIgnore : nsEventStatus_eConsumeNoDefault;
+  }
+
+  double delta = -aEvent.mPanDisplacement.x / mWidget.BackingScaleFactor() / kWholePagePixelSize;
+  if (!SwipingInAllowedDirection()) {
+    delta /= kRubberBandResistanceFactor;
+  }
+  mGestureAmount = ClampToAllowedRange(mGestureAmount + delta);
+  SendSwipeEvent(eSwipeGestureUpdate, 0, mGestureAmount, aEvent.mTimeStamp);
+
+  if (aEvent.mType != PanGestureInput::PANGESTURE_END) {
+    double elapsedSeconds = std::max(0.008, (aEvent.mTimeStamp - mLastEventTimeStamp).ToSeconds());
+    mCurrentVelocity = delta / elapsedSeconds;
+    mLastEventTimeStamp = aEvent.mTimeStamp;
+  } else {
+    mEventsAreControllingSwipe = false;
+    bool didSwipeSucceed = SwipingInAllowedDirection() && ComputeSwipeSuccess();
+    double targetValue = 0.0;
+    if (didSwipeSucceed) {
+      // Let's use same timestamp as previous event because this is caused by
+      // the preceding event.
+      SendSwipeEvent(eSwipeGesture, mSwipeDirection, 0.0, aEvent.mTimeStamp);
+      targetValue = SwipeSuccessTargetValue();
+    }
+    StartAnimating(targetValue);
+  }
+
+  return nsEventStatus_eConsumeNoDefault;
+}
+
+void SwipeTracker::StartAnimating(double aTargetValue) {
+  mAxis.SetPosition(mGestureAmount);
+  mAxis.SetDestination(aTargetValue);
+  mAxis.SetVelocity(mCurrentVelocity);
+
+  mLastAnimationFrameTime = TimeStamp::Now();
+
+  // Add ourselves as a refresh driver observer. The refresh driver
+  // will call WillRefresh for each animation frame until we
+  // unregister ourselves.
+  MOZ_ASSERT(!mRegisteredWithRefreshDriver);
+  if (mRefreshDriver) {
+    mRefreshDriver->AddRefreshObserver(this, FlushType::Style, "Swipe animation");
+    mRegisteredWithRefreshDriver = true;
+  }
+}
+
+void SwipeTracker::WillRefresh(mozilla::TimeStamp aTime) {
+  TimeStamp now = TimeStamp::Now();
+  mAxis.Simulate(now - mLastAnimationFrameTime);
+  mLastAnimationFrameTime = now;
+
+  bool isFinished = mAxis.IsFinished(1.0 / kWholePagePixelSize);
+  mGestureAmount = (isFinished ? mAxis.GetDestination() : mAxis.GetPosition());
+  SendSwipeEvent(eSwipeGestureUpdate, 0, mGestureAmount, now);
+
+  if (isFinished) {
+    UnregisterFromRefreshDriver();
+    SwipeFinished(now);
+  }
+}
+
+void SwipeTracker::CancelSwipe(const TimeStamp& aTimeStamp) {
+  SendSwipeEvent(eSwipeGestureEnd, 0, 0.0, aTimeStamp);
+}
+
+void SwipeTracker::SwipeFinished(const TimeStamp& aTimeStamp) {
+  SendSwipeEvent(eSwipeGestureEnd, 0, 0.0, aTimeStamp);
+  mWidget.SwipeFinished();
+}
+
+void SwipeTracker::UnregisterFromRefreshDriver() {
+  if (mRegisteredWithRefreshDriver) {
+    MOZ_ASSERT(mRefreshDriver, "How were we able to register, then?");
+    mRefreshDriver->RemoveRefreshObserver(this, FlushType::Style);
+  }
+  mRegisteredWithRefreshDriver = false;
+}
+
+/* static */ WidgetSimpleGestureEvent SwipeTracker::CreateSwipeGestureEvent(
+    EventMessage aMsg, nsIWidget* aWidget, const LayoutDeviceIntPoint& aPosition,
+    const TimeStamp& aTimeStamp) {
+  // XXX Why isn't this initialized with nsCocoaUtils::InitInputEvent()?
+  WidgetSimpleGestureEvent geckoEvent(true, aMsg, aWidget);
+  geckoEvent.mModifiers = 0;
+  // XXX How about geckoEvent.mTime?
+  geckoEvent.mTimeStamp = aTimeStamp;
+  geckoEvent.mRefPoint = aPosition;
+  geckoEvent.mButtons = 0;
+  return geckoEvent;
+}
+
+bool SwipeTracker::SendSwipeEvent(EventMessage aMsg, uint32_t aDirection, double aDelta,
+                                  const TimeStamp& aTimeStamp) {
+  WidgetSimpleGestureEvent geckoEvent =
+      CreateSwipeGestureEvent(aMsg, &mWidget, mEventPosition, aTimeStamp);
+  geckoEvent.mDirection = aDirection;
+  geckoEvent.mDelta = aDelta;
+  geckoEvent.mAllowedDirections = mAllowedDirections;
+  return mWidget.DispatchWindowEvent(geckoEvent);
+}
+
+}  // namespace mozilla