/* -*- 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/. */ #ifndef SwipeTracker_h #define SwipeTracker_h #include "EventForwards.h" #include "mozilla/layers/AxisPhysicsMSDModel.h" #include "mozilla/RefPtr.h" #include "mozilla/TimeStamp.h" #include "nsRefreshDriver.h" #include "Units.h" class nsIPresShell; namespace mozilla { class PanGestureInput; /** * SwipeTracker turns PanGestureInput events into swipe events * (WidgetSimpleGestureEvent) and dispatches them into Gecko. * The swiping behavior mirrors the behavior of the Cocoa API * -[NSEvent trackSwipeEventWithOptions:dampenAmountThresholdMin:max:usingHandler:]. * The advantage of using this class over the Cocoa API is that this class * properly supports submitting queued up events to it, and that it hopefully * doesn't intermittently break scrolling the way the Cocoa API does (bug 927702). * * The swipe direction is either left or right. It is determined before the * SwipeTracker is created and stays fixed during the swipe. * During the swipe, the swipe has a current "value" which is between 0 and the * target value. The target value is either 1 (swiping left) or -1 (swiping * right) - see SwipeSuccessTargetValue(). * A swipe can either succeed or fail. If it succeeds, the swipe animation * animates towards the success target value; if it fails, it animates back to * a value of 0. A swipe can only succeed if the user is swiping in an allowed * direction. (Since both the allowed directions and the swipe direction are * known at swipe start time, it's clear from the beginning whether a swipe is * doomed to fail. In that case, the purpose of the SwipeTracker is to simulate * a bounce-back animation.) */ class SwipeTracker final : public nsARefreshObserver { public: NS_INLINE_DECL_REFCOUNTING(SwipeTracker, override) SwipeTracker(nsChildView& aWidget, const PanGestureInput& aSwipeStartEvent, uint32_t aAllowedDirections, uint32_t aSwipeDirection); void Destroy(); nsEventStatus ProcessEvent(const PanGestureInput& aEvent); void CancelSwipe(); static WidgetSimpleGestureEvent CreateSwipeGestureEvent(EventMessage aMsg, nsIWidget* aWidget, const LayoutDeviceIntPoint& aPosition); // nsARefreshObserver void WillRefresh(mozilla::TimeStamp aTime) override; protected: ~SwipeTracker(); bool SwipingInAllowedDirection() const { return mAllowedDirections & mSwipeDirection; } double SwipeSuccessTargetValue() const; double ClampToAllowedRange(double aGestureAmount) const; bool ComputeSwipeSuccess() const; void StartAnimating(double aTargetValue); void SwipeFinished(); void UnregisterFromRefreshDriver(); bool SendSwipeEvent(EventMessage aMsg, uint32_t aDirection, double aDelta); nsChildView& mWidget; RefPtr<nsRefreshDriver> mRefreshDriver; layers::AxisPhysicsMSDModel mAxis; const LayoutDeviceIntPoint mEventPosition; TimeStamp mLastEventTimeStamp; TimeStamp mLastAnimationFrameTime; const uint32_t mAllowedDirections; const uint32_t mSwipeDirection; double mGestureAmount; double mCurrentVelocity; bool mEventsAreControllingSwipe; bool mEventsHaveStartedNewGesture; bool mRegisteredWithRefreshDriver; }; } // namespace mozilla #endif // SwipeTracker_h