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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 */
#ifndef mozilla_layers_OverscrollHandoffChain_h
#define mozilla_layers_OverscrollHandoffChain_h
#include <vector>
#include "mozilla/RefPtr.h" // for RefPtr
#include "nsISupportsImpl.h" // for NS_INLINE_DECL_THREADSAFE_REFCOUNTING
#include "APZUtils.h" // for CancelAnimationFlags
#include "mozilla/layers/LayersTypes.h" // for Layer::ScrollDirection
#include "Units.h" // for ScreenPoint
namespace mozilla {
class InputData;
namespace layers {
class AsyncPanZoomController;
* This class represents the chain of APZCs along which overscroll is handed
* off. It is created by APZCTreeManager by starting from an initial APZC which
* is the target for input events, and following the scroll parent ID links
* (often but not always corresponding to parent pointers in the APZC tree),
* then adjusting for scrollgrab.
class OverscrollHandoffChain {
// Reference-counted classes cannot have public destructors.
// Threadsafe so that the controller and sampler threads can both maintain
// nsRefPtrs to the same handoff chain.
// Mutable so that we can pass around the class by
// RefPtr<const OverscrollHandoffChain> and thus enforce that, once built,
// the chain is not modified.
* Methods for building the handoff chain.
* These should be used only by
* AsyncPanZoomController::BuildOverscrollHandoffChain().
void Add(AsyncPanZoomController* aApzc);
void SortByScrollPriority();
* Methods for accessing the handoff chain.
uint32_t Length() const { return mChain.size(); }
const RefPtr<AsyncPanZoomController>& GetApzcAtIndex(uint32_t aIndex) const;
// Returns Length() if |aApzc| is not on this chain.
uint32_t IndexOf(const AsyncPanZoomController* aApzc) const;
* Convenience methods for performing operations on APZCs in the chain.
// Flush repaints all the way up the chain.
void FlushRepaints() const;
// Cancel animations all the way up the chain.
void CancelAnimations(CancelAnimationFlags aFlags = Default) const;
// Clear overscroll all the way up the chain.
void ClearOverscroll() const;
// Snap back the APZC that is overscrolled on the subset of the chain from
// |aStart| onwards, if any.
void SnapBackOverscrolledApzc(const AsyncPanZoomController* aStart) const;
// Similar to above SnapbackOverscrolledApzc but for pan gestures with
// momentum events, this function doesn't end up calling each APZC's
// ScrollSnap.
// |aVelocity| is the initial velocity of |aStart|.
void SnapBackOverscrolledApzcForMomentum(
const AsyncPanZoomController* aStart,
const ParentLayerPoint& aVelocity) const;
// Determine whether the given APZC, or any APZC further in the chain,
// has room to be panned.
bool CanBePanned(const AsyncPanZoomController* aApzc) const;
// Determine whether the given APZC, or any APZC further in the chain,
// can scroll in the given direction.
bool CanScrollInDirection(const AsyncPanZoomController* aApzc,
ScrollDirection aDirection) const;
// Determine whether any APZC along this handoff chain is overscrolled.
bool HasOverscrolledApzc() const;
// Determine whether any APZC along this handoff chain has been flung fast.
bool HasFastFlungApzc() const;
// Determine whether any APZC along this handoff chain is autoscroll.
bool HasAutoscrollApzc() const;
// Find the first APZC in this handoff chain that can be scrolled by |aInput|.
// Since overscroll-behavior can restrict handoff in some directions,
// |aOutAllowedScrollDirections| is populated with the scroll directions
// in which scrolling of the returned APZC is allowed.
// |aIncludeOverscroll| is an optional flag whether to consider overscrollable
// as scrollable or not.
enum class IncludeOverscroll : bool { No, Yes };
RefPtr<AsyncPanZoomController> FindFirstScrollable(
const InputData& aInput, ScrollDirections* aOutAllowedScrollDirections,
IncludeOverscroll aIncludeOverscroll = IncludeOverscroll::Yes) const;
// Return a pair of true and the root content APZC if all non-root APZCs in
// this handoff chain starting from |aApzc| are not able to scroll downwards
// (i.e. there is no room to scroll downwards in each APZC respectively) and
// there is any contents covered by the dynamic toolbar, otherwise return a
// pair of false and nullptr.
std::tuple<bool, const AsyncPanZoomController*>
const AsyncPanZoomController* aApzc) const;
bool ScrollingUpWillTriggerPullToRefresh(
const AsyncPanZoomController* aApzc) const;
std::vector<RefPtr<AsyncPanZoomController>> mChain;
typedef void (AsyncPanZoomController::*APZCMethod)();
typedef bool (AsyncPanZoomController::*APZCPredicate)() const;
void ForEachApzc(APZCMethod aMethod) const;
bool AnyApzc(APZCPredicate aPredicate) const;
* This class groups the state maintained during overscroll handoff.
struct OverscrollHandoffState {
OverscrollHandoffState(const OverscrollHandoffChain& aChain,
const ScreenPoint& aPanDistance,
ScrollSource aScrollSource)
: mChain(aChain),
mScrollSource(aScrollSource) {}
// The chain of APZCs along which we hand off scroll.
// This is const to indicate that the chain does not change over the
// course of handoff.
const OverscrollHandoffChain& mChain;
// The index of the APZC in the chain that we are currently giving scroll to.
// This is non-const to indicate that this changes over the course of handoff.
uint32_t mChainIndex;
// The total distance since touch-start of the pan that triggered the
// handoff. This is const to indicate that it does not change over the
// course of handoff.
// The x/y components of this are non-negative.
const ScreenPoint mPanDistance;
ScrollSource mScrollSource;
// The total amount of actual movement that this scroll caused, including
// scrolling and changes to overscroll. This starts at zero and is accumulated
// over the course of the handoff.
ScreenPoint mTotalMovement;
* This class groups the state maintained during fling handoff.
struct FlingHandoffState {
// The velocity of the fling being handed off.
ParentLayerPoint mVelocity;
// The chain of APZCs along which we hand off the fling.
// Unlike in OverscrollHandoffState, this is stored by RefPtr because
// otherwise it may not stay alive for the entire handoff.
RefPtr<const OverscrollHandoffChain> mChain;
// The time duration between the touch start and the touch move that started
// the pan gesture which triggered this fling. In other words, the time it
// took for the finger to move enough to cross the touch slop threshold.
// Nothing if this fling was not immediately caused by a touch pan.
Maybe<TimeDuration> mTouchStartRestingTime;
// The slowest panning velocity encountered during the pan that triggered this
// fling.
ParentLayerCoord mMinPanVelocity;
// Whether handoff has happened by this point, or we're still process
// the original fling.
bool mIsHandoff;
// The single APZC that was scrolled by the pan that started this fling.
// The fling is only allowed to scroll this APZC, too.
// Used only if immediate scroll handoff is disallowed.
RefPtr<const AsyncPanZoomController> mScrolledApzc;
} // namespace layers
} // namespace mozilla
#endif /* mozilla_layers_OverscrollHandoffChain_h */