tor-browser

InputBlockState.h (22186B)

---

/* -*- 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 mozilla_layers_InputBlockState_h
#define mozilla_layers_InputBlockState_h

#include "InputData.h"  // for MultiTouchInput
#include "Units.h"
#include "mozilla/RefCounted.h"  // for RefCounted
#include "mozilla/RefPtr.h"      // for RefPtr
#include "mozilla/StaticPrefs_apz.h"
#include "mozilla/gfx/Matrix.h"  // for Matrix4x4
#include "mozilla/layers/APZUtils.h"
#include "mozilla/layers/LayersTypes.h"  // for TouchBehaviorFlags
#include "mozilla/layers/AsyncDragMetrics.h"
#include "mozilla/layers/TouchCounter.h"
#include "mozilla/TimeStamp.h"  // for TimeStamp
#include "nsTArray.h"           // for nsTArray

namespace mozilla {
namespace layers {

class AsyncPanZoomController;
class OverscrollHandoffChain;
class CancelableBlockState;
class TouchBlockState;
class WheelBlockState;
class DragBlockState;
class PanGestureBlockState;
class PinchGestureBlockState;
class KeyboardBlockState;
class InputQueueIterator;
enum class BrowserGestureResponse : bool;

/**
* A base class that stores state common to various input blocks.
* Note that the InputBlockState constructor acquires the tree lock, so callers
* from inside AsyncPanZoomController should ensure that the APZC lock is not
* held.
*/
class InputBlockState : public RefCounted<InputBlockState> {
public:
 MOZ_DECLARE_REFCOUNTED_TYPENAME(InputBlockState)

 static const uint64_t NO_BLOCK_ID = 0;

 enum class TargetConfirmationState : uint8_t {
   eUnconfirmed,
   eTimedOut,
   eConfirmed
 };

 InputBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                 TargetConfirmationFlags aFlags);
 virtual ~InputBlockState() = default;

 virtual CancelableBlockState* AsCancelableBlock() { return nullptr; }
 virtual TouchBlockState* AsTouchBlock() { return nullptr; }
 virtual const TouchBlockState* AsTouchBlock() const { return nullptr; }
 virtual WheelBlockState* AsWheelBlock() { return nullptr; }
 virtual DragBlockState* AsDragBlock() { return nullptr; }
 virtual PanGestureBlockState* AsPanGestureBlock() { return nullptr; }
 virtual PinchGestureBlockState* AsPinchGestureBlock() { return nullptr; }
 virtual KeyboardBlockState* AsKeyboardBlock() { return nullptr; }
 virtual Maybe<LayersId> WheelTransactionLayersId() const { return Nothing(); }

 virtual bool SetConfirmedTargetApzc(
     const RefPtr<AsyncPanZoomController>& aTargetApzc,
     TargetConfirmationState aState, InputQueueIterator aFirstInput,
     bool aForScrollbarDrag);
 const RefPtr<AsyncPanZoomController>& GetTargetApzc() const;
 const RefPtr<const OverscrollHandoffChain>& GetOverscrollHandoffChain() const;
 uint64_t GetBlockId() const;

 bool IsTargetConfirmed() const;

 virtual bool ShouldDropEvents() const;

 void SetScrolledApzc(AsyncPanZoomController* aApzc);
 AsyncPanZoomController* GetScrolledApzc() const;
 bool IsDownchainOfScrolledApzc(AsyncPanZoomController* aApzc) const;

 /**
  * Dispatch the event to the target APZC. Mostly this is a hook for
  * subclasses to do any per-event processing they need to.
  */
 virtual void DispatchEvent(const InputData& aEvent) const;

 /**
  * Return true if this input block must stay active if it would otherwise
  * be removed as the last item in the pending queue.
  */
 virtual bool MustStayActive() = 0;

 const ScreenToParentLayerMatrix4x4& GetTransformToApzc() const {
   return mTransformToApzc;
 }

protected:
 virtual void UpdateTargetApzc(
     const RefPtr<AsyncPanZoomController>& aTargetApzc);

 const AsyncPanZoomController* TargetApzc() const { return mTargetApzc.get(); }

private:
 // Checks whether |aA| is an ancestor of |aB| (or the same as |aB|) in
 // |mOverscrollHandoffChain|.
 bool IsDownchainOf(AsyncPanZoomController* aA,
                    AsyncPanZoomController* aB) const;

private:
 RefPtr<AsyncPanZoomController> mTargetApzc;
 bool mRequiresTargetConfirmation;
 const uint64_t mBlockId;

 // The APZC that was actually scrolled by events in this input block.
 // This is used in configurations where a single input block is only
 // allowed to scroll a single APZC (configurations where
 // StaticPrefs::apz_allow_immediate_handoff() is false). Set the first time an
 // input event in this block scrolls an APZC.
 RefPtr<AsyncPanZoomController> mScrolledApzc;

protected:
 TargetConfirmationState mTargetConfirmed;
 RefPtr<const OverscrollHandoffChain> mOverscrollHandoffChain;

 // Used to transform events from global screen space to |mTargetApzc|'s
 // screen space. It's cached at the beginning of the input block so that
 // all events in the block are in the same coordinate space.
 ScreenToParentLayerMatrix4x4 mTransformToApzc;
};

/**
* This class represents a set of events that can be cancelled by web content
* via event listeners.
*
* Each cancelable input block can be cancelled by web content, and
* this information is stored in the mPreventDefault flag. Because web
* content runs on the Gecko main thread, we cannot always wait for web
* content's response. Instead, there is a timeout that sets this flag in the
* case where web content doesn't respond in time. The mContentResponded and
* mContentResponseTimerExpired flags indicate which of these scenarios
* occurred.
*/
class CancelableBlockState : public InputBlockState {
public:
 CancelableBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                      TargetConfirmationFlags aFlags);

 CancelableBlockState* AsCancelableBlock() override { return this; }

 /**
  * Record whether or not content cancelled this block of events.
  * @param aPreventDefault true iff the block is cancelled.
  * @return false if this block has already received a response from
  *         web content, true if not.
  */
 virtual bool SetContentResponse(bool aPreventDefault);

 /**
  * Record that content didn't respond in time.
  * @return false if this block already timed out, true if not.
  */
 virtual bool TimeoutContentResponse();

 /**
  * Checks if the content response timer has already expired.
  */
 bool IsContentResponseTimerExpired() const;

 /**
  * Checks if the content has responded.
  */
 bool HasContentResponded() const { return mContentResponded; }

 /**
  * @return true iff web content cancelled this block of events.
  */
 bool IsDefaultPrevented() const;

 /**
  * @return true iff this block has received all the information needed
  *         to properly dispatch the events in the block.
  */
 virtual bool IsReadyForHandling() const;

 /**
  * Return a descriptive name for the block kind.
  */
 virtual const char* Type() = 0;

 bool ShouldDropEvents() const override;

 bool HasStateBeenReset() const { return mHasStateBeenReset; };
 void ResetState() { mHasStateBeenReset = true; }

 void ResetContentResponseTimerExpired() {
   mContentResponseTimerExpired = false;
   mContentResponded = false;
 }

private:
 bool mPreventDefault;
 bool mContentResponded;
 bool mContentResponseTimerExpired;
 bool mHasStateBeenReset;
};

/**
* A single block of wheel events.
*/
class WheelBlockState : public CancelableBlockState {
public:
 WheelBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                 TargetConfirmationFlags aFlags,
                 const ScrollWheelInput& aEvent);

 bool SetContentResponse(bool aPreventDefault) override;
 bool MustStayActive() override;
 const char* Type() override;
 bool SetConfirmedTargetApzc(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                             TargetConfirmationState aState,
                             InputQueueIterator aFirstInput,
                             bool aForScrollbarDrag) override;

 WheelBlockState* AsWheelBlock() override { return this; }

 /**
  * Determine whether this wheel block is accepting new events.
  */
 bool ShouldAcceptNewEvent() const;

 /**
  * Call to check whether a wheel event will cause the current transaction to
  * timeout.
  */
 bool MaybeTimeout(const ScrollWheelInput& aEvent);

 /**
  * Called from APZCTM when a mouse move or drag+drop event occurs, before
  * the event has been processed.
  */
 void OnMouseMove(const ScreenIntPoint& aPoint,
                  const Maybe<ScrollableLayerGuid>& aTargetGuid);

 /**
  * Returns whether or not the block is participating in a wheel transaction.
  * This means that the block is the most recent input block to be created,
  * and no events have occurred that would require scrolling a different
  * frame.
  *
  * @return True if in a transaction, false otherwise.
  */
 bool InTransaction() const;

 /**
  * Mark the block as no longer participating in a wheel transaction. This
  * will force future wheel events to begin a new input block.
  */
 void EndTransaction();

 /**
  * @return Whether or not overscrolling is prevented for this wheel block.
  */
 bool AllowScrollHandoff() const;

 /**
  * Called to check and possibly end the transaction due to a timeout.
  *
  * @return True if the transaction ended, false otherwise.
  */
 bool MaybeTimeout(const TimeStamp& aTimeStamp);

 /**
  * Update the wheel transaction state for a new event.
  */
 void Update(ScrollWheelInput& aEvent);

 ScrollDirections GetAllowedScrollDirections() const {
   return mAllowedScrollDirections;
 }

 Maybe<LayersId> WheelTransactionLayersId() const override;

protected:
 void UpdateTargetApzc(
     const RefPtr<AsyncPanZoomController>& aTargetApzc) override;

private:
 TimeStamp mLastEventTime;
 TimeStamp mLastMouseMove;
 uint32_t mScrollSeriesCounter;
 bool mTransactionEnded;
 bool mIsScrollable = true;
 ScrollDirections mAllowedScrollDirections;
};

/**
* A block of mouse events that are part of a drag
*/
class DragBlockState : public CancelableBlockState {
public:
 DragBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                TargetConfirmationFlags aFlags, const MouseInput& aEvent);

 bool MustStayActive() override;
 const char* Type() override;

 bool HasReceivedMouseUp();
 void MarkMouseUpReceived();

 DragBlockState* AsDragBlock() override { return this; }

 void SetInitialThumbPos(OuterCSSCoord aThumbPos);
 void SetDragMetrics(const AsyncDragMetrics& aDragMetrics,
                     const CSSRect& aScrollableRect);

 void DispatchEvent(const InputData& aEvent) const override;

private:
 AsyncDragMetrics mDragMetrics;
 OuterCSSCoord mInitialThumbPos;
 CSSRect mInitialScrollableRect;
 bool mReceivedMouseUp;
};

/**
* A single block of pan gesture events.
*/
class PanGestureBlockState : public CancelableBlockState {
public:
 PanGestureBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                      TargetConfirmationFlags aFlags,
                      const PanGestureInput& aEvent);

 bool SetContentResponse(bool aPreventDefault) override;
 bool IsReadyForHandling() const override;
 bool MustStayActive() override;
 const char* Type() override;
 bool SetConfirmedTargetApzc(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                             TargetConfirmationState aState,
                             InputQueueIterator aFirstInput,
                             bool aForScrollbarDrag) override;

 PanGestureBlockState* AsPanGestureBlock() override { return this; }

 bool ShouldDropEvents() const override;

 bool TimeoutContentResponse() override;

 /**
  * @return Whether or not overscrolling is prevented for this block.
  */
 bool AllowScrollHandoff() const;

 bool WasInterrupted() const { return mInterrupted; }

 void SetNeedsToWaitForContentResponse(bool aWaitForContentResponse);
 void SetNeedsToWaitForBrowserGestureResponse(
     bool aWaitForBrowserGestureResponse);
 void SetBrowserGestureResponse(BrowserGestureResponse aResponse);

 ScrollDirections GetAllowedScrollDirections() const {
   return mAllowedScrollDirections;
 }

 bool IsWaitingForBrowserGestureResponse() const {
   return mWaitingForBrowserGestureResponse;
 }
 bool IsWaitingForContentResponse() const {
   return mWaitingForContentResponse;
 }
 Maybe<LayersId> WheelTransactionLayersId() const override;

 void ConfirmForHoldGesture() {
   // Hold gestures get their own input block, but do not generate
   // any events that get to web content (because the PANGESTURE_MAYSTART
   // event has a zero delta). As a result, do not wait for a content
   // response for them because it will never arrive.
   mTargetConfirmed = InputBlockState::TargetConfirmationState::eConfirmed;
 }

private:
 bool mInterrupted;
 bool mWaitingForContentResponse;
 // A pan gesture may be used for browser's swipe gestures so APZ needs to wait
 // for the response from the browser whether the gesture has been used for
 // swipe or not. This `mWaitingForBrowserGestureResponse` flag represents the
 // waiting state. And below `mStartedBrowserGesture` represents the response
 // from the browser.
 bool mWaitingForBrowserGestureResponse;
 bool mStartedBrowserGesture;
 ScrollDirections mAllowedScrollDirections;
};

/**
* A single block of pinch gesture events.
*/
class PinchGestureBlockState : public CancelableBlockState {
public:
 PinchGestureBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                        TargetConfirmationFlags aFlags);

 bool SetContentResponse(bool aPreventDefault) override;
 bool IsReadyForHandling() const override;
 bool MustStayActive() override;
 const char* Type() override;

 PinchGestureBlockState* AsPinchGestureBlock() override { return this; }

 bool WasInterrupted() const { return mInterrupted; }

 void SetNeedsToWaitForContentResponse(bool aWaitForContentResponse);

 bool IsWaitingForContentResponse() const {
   return mWaitingForContentResponse;
 }

private:
 bool mInterrupted;
 bool mWaitingForContentResponse;
};

/**
* This class represents a single touch block. A touch block is
* a set of touch events that can be cancelled by web content via
* touch event listeners.
*
* Every touch-start event creates a new touch block. In this case, the
* touch block consists of the touch-start, followed by all touch events
* up to but not including the next touch-start (except in the case where
* a long-tap happens, see below). Note that in particular we cannot know
* when a touch block ends until the next one is started. Most touch
* blocks are created by receipt of a touch-start event.
*
* Every long-tap event also creates a new touch block, since it can also
* be consumed by web content. In this case, when the long-tap event is
* dispatched to web content, a new touch block is started to hold the remaining
* touch events, up to but not including the next touch start (or long-tap).
*
* Additionally, if touch-action is enabled, each touch block should
* have a set of allowed touch behavior flags; one for each touch point.
* This also requires running code on the Gecko main thread, and so may
* be populated with some latency. The mAllowedTouchBehaviorSet and
* mAllowedTouchBehaviors variables track this information.
*/
class TouchBlockState : public CancelableBlockState {
public:
 explicit TouchBlockState(const RefPtr<AsyncPanZoomController>& aTargetApzc,
                          TargetConfirmationFlags aFlags,
                          TouchCounter& aTouchCounter);

 TouchBlockState* AsTouchBlock() override { return this; }
 const TouchBlockState* AsTouchBlock() const override { return this; }

 /**
  * Set the allowed touch behavior flags for this block.
  * @return false if this block already has these flags set, true if not.
  */
 bool SetAllowedTouchBehaviors(const nsTArray<TouchBehaviorFlags>& aBehaviors);
 /**
  * If the allowed touch behaviors have been set, populate them into
  * |aOutBehaviors| and return true. Else, return false.
  */
 bool GetAllowedTouchBehaviors(
     nsTArray<TouchBehaviorFlags>& aOutBehaviors) const;

 /**
  * Returns true if the allowed touch behaviours have been set, or if touch
  * action is disabled.
  */
 bool HasAllowedTouchBehaviors() const;

 /**
  * Copy various properties from another block.
  */
 void CopyPropertiesFrom(const TouchBlockState& aOther);

 /**
  * @return true iff this block has received all the information needed
  *         to properly dispatch the events in the block.
  */
 bool IsReadyForHandling() const override;

 /**
  * Sets a flag that indicates this input block occurred while the APZ was
  * in a state of fast flinging. This affects gestures that may be produced
  * from input events in this block.
  */
 void SetDuringFastFling();
 /**
  * @return true iff SetDuringFastFling was called on this block.
  */
 bool IsDuringFastFling() const;
 /**
  * Set the single-tap state flag that indicates that this touch block
  * triggered (1) a click, (2) not a click, or (3) not yet sure it will trigger
  * a click or not.
  */
 void SetSingleTapState(apz::SingleTapState aState);
 apz::SingleTapState SingleTapState() const { return mSingleTapState; }

 /**
  * @return false iff touch-action is enabled and the allowed touch behaviors
  * for this touch block do not allow pinch-zooming.
  */
 bool TouchActionAllowsPinchZoom() const;
 /**
  * @return false iff touch-action is enabled and the allowed touch behaviors
  * for this touch block do not allow double-tap zooming.
  */
 bool TouchActionAllowsDoubleTapZoom() const;
 /**
  * @return false iff touch-action is enabled and the allowed touch behaviors
  *         for the first touch point do not allow panning in the specified
  *         direction(s).
  */
 bool TouchActionAllowsPanningX() const;
 bool TouchActionAllowsPanningY() const;
 bool TouchActionAllowsPanningXY() const;

 /**
  * Notifies the input block of an incoming touch event so that the block can
  * update its internal slop state. "Slop" refers to the area around the
  * initial touchstart where we drop touchmove events so that content doesn't
  * see them. The |aApzcCanConsumeEvents| parameter is factored into how large
  * the slop area is - if this is true the slop area is larger.
  * @return true iff the provided event is a touchmove in the slop area and
  *         so should not be sent to content.
  */
 bool UpdateSlopState(const MultiTouchInput& aInput,
                      bool aApzcCanConsumeEvents);
 bool IsInSlop() const;
 bool ForLongTap() const { return mForLongTap; }
 void SetForLongTap() { mForLongTap = true; }
 bool WasLongTapProcessed() const { return mLongTapWasProcessed; }
 void SetLongTapProcessed() {
   MOZ_ASSERT(!mForLongTap);
   mLongTapWasProcessed = true;
   mIsWaitingLongTapResult = false;
 }

 void SetWaitingLongTapResult(bool aResult) {
   MOZ_ASSERT(!mForLongTap);
   mIsWaitingLongTapResult = aResult;
 }
 bool IsWaitingLongTapResult() const { return mIsWaitingLongTapResult; }

 void SetNeedsToWaitTouchMove(bool aNeedsWaitTouchMove) {
   mNeedsWaitTouchMove = aNeedsWaitTouchMove;
 }
 bool IsReadyForCallback() const { return !mNeedsWaitTouchMove; };

 /**
  * Based on the slop origin and the given input event, return a best guess
  * as to the pan direction of this touch block. Returns Nothing() if no guess
  * can be made.
  */
 Maybe<ScrollDirection> GetBestGuessPanDirection(
     const MultiTouchInput& aInput) const;

 /**
  * Returns the number of touch points currently active.
  */
 uint32_t GetActiveTouchCount() const;

 void DispatchEvent(const InputData& aEvent) const override;
 bool MustStayActive() override;
 const char* Type() override;
 TimeDuration GetTimeSinceBlockStart() const;
 bool IsTargetOriginallyConfirmed() const;

private:
 nsTArray<TouchBehaviorFlags> mAllowedTouchBehaviors;
 bool mAllowedTouchBehaviorSet;
 bool mDuringFastFling;
 bool mInSlop;
 // A long tap involves two touch blocks: the original touch
 // block containing the `touchstart`, and a second one
 // specifically for the long tap. `mForLongTap` is set on the
 // second touch block. `mLongTapWasProcessed` is set
 // on the first touch block after the long tap was processed.
 bool mForLongTap;
 bool mLongTapWasProcessed;

 // A flag representing a state while we are waiting for a content response for
 // the long tap.
 // The reason why we have this flag separately from `mLongTapWasProcessed` is
 // the block is not ready to be processed during the wait, and is ready once
 // after `mLongTapWasProcessed` became true.
 bool mIsWaitingLongTapResult;
 // A flag representing a state that this block still needs to wait for a
 // content response for a touch move event. It will be set just before
 // triggering a long-press event.
 bool mNeedsWaitTouchMove;
 apz::SingleTapState mSingleTapState;
 ScreenIntPoint mSlopOrigin;
 // A reference to the InputQueue's touch counter
 TouchCounter& mTouchCounter;
 TimeStamp mStartTime;
 // The original `mTargetConfirmed`. This is necessary to tell whether there's
 // any APZ-aware event listener in the content after we've got a content
 // response, because in the case of a long-tap event we need to wait a content
 // response again.
 TargetConfirmationState mOriginalTargetConfirmedState;
};

/**
* This class represents a set of keyboard inputs targeted at the same Apzc.
*/
class KeyboardBlockState : public InputBlockState {
public:
 explicit KeyboardBlockState(
     const RefPtr<AsyncPanZoomController>& aTargetApzc);

 KeyboardBlockState* AsKeyboardBlock() override { return this; }

 bool MustStayActive() override { return false; }

 /**
  * @return Whether or not overscrolling is prevented for this keyboard block.
  */
 bool AllowScrollHandoff() const { return false; }
};

}  // namespace layers
}  // namespace mozilla

#endif  // mozilla_layers_InputBlockState_h