SwipeTracker.h - mozsearch

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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/. */

#ifndef SwipeTracker_h

#define SwipeTracker_h

#include "EventForwards.h"

#include "mozilla/layers/AxisPhysicsMSDModel.h"

#include "mozilla/RefPtr.h"

#include "mozilla/TimeStamp.h"

#include "nsRefreshObservers.h"

#include "Units.h"

class nsIWidget;

class nsRefreshDriver;

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(nsIWidget& aWidget, const PanGestureInput& aSwipeStartEvent,

               uint32_t aAllowedDirections, uint32_t aSwipeDirection);

  void Destroy();

  nsEventStatus ProcessEvent(const PanGestureInput& aEvent,

                             bool aProcessingFirstEvent = false);

  void CancelSwipe(const TimeStamp& aTimeStamp);

  static WidgetSimpleGestureEvent CreateSwipeGestureEvent(

      EventMessage aMsg, nsIWidget* aWidget,

      const LayoutDeviceIntPoint& aPosition, const TimeStamp& aTimeStamp);

  // nsARefreshObserver

  void WillRefresh(mozilla::TimeStamp aTime) override;

  static bool CanTriggerSwipe(const PanGestureInput& aPanInput);

 protected:

  ~SwipeTracker();

  bool SwipingInAllowedDirection() const {

    return mAllowedDirections & mSwipeDirection;

  double SwipeSuccessTargetValue() const;

  double ClampToAllowedRange(double aGestureAmount) const;

  bool ComputeSwipeSuccess() const;

  void StartAnimating(double aStartValue, double aTargetValue);

  void SwipeFinished(const TimeStamp& aTimeStamp);

  void UnregisterFromRefreshDriver();

  bool SendSwipeEvent(EventMessage aMsg, uint32_t aDirection, double aDelta,

                      const TimeStamp& aTimeStamp);

  nsIWidget& mWidget;

  RefPtr<nsRefreshDriver> mRefreshDriver;

  layers::AxisPhysicsMSDModel mAxis;

  const LayoutDeviceIntPoint mEventPosition;

  TimeStamp mLastEventTimeStamp;

  TimeStamp mLastAnimationFrameTime;

  const uint32_t mAllowedDirections;

  const uint32_t mSwipeDirection;

  double mGestureAmount = 0.0;

  double mCurrentVelocity = 0.0;

  bool mDeltaTypeIsPage = false;

  bool mEventsAreControllingSwipe = true;

  bool mEventsHaveStartedNewGesture = false;

  bool mRegisteredWithRefreshDriver = false;

};

struct SwipeEventQueue {

  SwipeEventQueue(uint32_t aAllowedDirections, uint64_t aInputBlockId)

      : allowedDirections(aAllowedDirections), inputBlockId(aInputBlockId) {}

  nsTArray<PanGestureInput> queuedEvents;

  uint32_t allowedDirections;

  uint64_t inputBlockId;

};

}  // namespace mozilla

#endif  // SwipeTracker_h