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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-07 19:33:14 +0000
commit36d22d82aa202bb199967e9512281e9a53db42c9 (patch)
tree105e8c98ddea1c1e4784a60a5a6410fa416be2de /gfx/layers/apz/src/AsyncPanZoomController.h
parentInitial commit. (diff)
downloadfirefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.tar.xz
firefox-esr-36d22d82aa202bb199967e9512281e9a53db42c9.zip
Adding upstream version 115.7.0esr.upstream/115.7.0esr
Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>
Diffstat (limited to 'gfx/layers/apz/src/AsyncPanZoomController.h')
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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 mozilla_layers_AsyncPanZoomController_h
+#define mozilla_layers_AsyncPanZoomController_h
+
+#include "mozilla/layers/GeckoContentController.h"
+#include "mozilla/layers/RepaintRequest.h"
+#include "mozilla/layers/SampleTime.h"
+#include "mozilla/layers/ScrollbarData.h"
+#include "mozilla/layers/ZoomConstraints.h"
+#include "mozilla/Atomics.h"
+#include "mozilla/Attributes.h"
+#include "mozilla/EventForwards.h"
+#include "mozilla/Monitor.h"
+#include "mozilla/RecursiveMutex.h"
+#include "mozilla/RefPtr.h"
+#include "mozilla/ScrollTypes.h"
+#include "mozilla/StaticPrefs_apz.h"
+#include "mozilla/UniquePtr.h"
+#include "InputData.h"
+#include "Axis.h" // for Axis, Side, etc.
+#include "ExpectedGeckoMetrics.h"
+#include "FlingAccelerator.h"
+#include "InputQueue.h"
+#include "APZUtils.h"
+#include "LayersTypes.h"
+#include "mozilla/gfx/Matrix.h"
+#include "nsRegion.h"
+#include "nsTArray.h"
+#include "PotentialCheckerboardDurationTracker.h"
+#include "RecentEventsBuffer.h" // for RecentEventsBuffer
+#include "SampledAPZCState.h"
+
+#include <iosfwd>
+
+namespace mozilla {
+
+namespace ipc {
+
+class SharedMemoryBasic;
+
+} // namespace ipc
+
+namespace wr {
+struct SampledScrollOffset;
+} // namespace wr
+
+namespace layers {
+
+class AsyncDragMetrics;
+class APZCTreeManager;
+struct ScrollableLayerGuid;
+class CompositorController;
+class GestureEventListener;
+struct AsyncTransform;
+class AsyncPanZoomAnimation;
+class StackScrollerFlingAnimation;
+template <typename FlingPhysics>
+class GenericFlingAnimation;
+class AndroidFlingPhysics;
+class DesktopFlingPhysics;
+class InputBlockState;
+struct FlingHandoffState;
+class TouchBlockState;
+class PanGestureBlockState;
+class OverscrollHandoffChain;
+struct OverscrollHandoffState;
+class StateChangeNotificationBlocker;
+class CheckerboardEvent;
+class OverscrollEffectBase;
+class WidgetOverscrollEffect;
+class GenericOverscrollEffect;
+class AndroidSpecificState;
+struct KeyboardScrollAction;
+struct ZoomTarget;
+
+namespace apz {
+struct AsyncScrollThumbTransformer;
+}
+
+// Base class for grouping platform-specific APZC state variables.
+class PlatformSpecificStateBase {
+ public:
+ virtual ~PlatformSpecificStateBase() = default;
+ virtual AndroidSpecificState* AsAndroidSpecificState() { return nullptr; }
+ // PLPPI = "ParentLayer pixels per (Screen) inch"
+ virtual AsyncPanZoomAnimation* CreateFlingAnimation(
+ AsyncPanZoomController& aApzc, const FlingHandoffState& aHandoffState,
+ float aPLPPI);
+ virtual UniquePtr<VelocityTracker> CreateVelocityTracker(Axis* aAxis);
+
+ static void InitializeGlobalState() {}
+};
+
+/*
+ * Represents a transform from the ParentLayer coordinate space of an APZC
+ * to the ParentLayer coordinate space of its parent APZC.
+ * Each layer along the way contributes to the transform. We track
+ * contributions that are perspective transforms separately, as sometimes
+ * these require special handling.
+ */
+struct AncestorTransform {
+ gfx::Matrix4x4 mTransform;
+ gfx::Matrix4x4 mPerspectiveTransform;
+
+ AncestorTransform() = default;
+
+ AncestorTransform(const gfx::Matrix4x4& aTransform,
+ bool aTransformIsPerspective) {
+ (aTransformIsPerspective ? mPerspectiveTransform : mTransform) = aTransform;
+ }
+
+ AncestorTransform(const gfx::Matrix4x4& aTransform,
+ const gfx::Matrix4x4& aPerspectiveTransform)
+ : mTransform(aTransform), mPerspectiveTransform(aPerspectiveTransform) {}
+
+ gfx::Matrix4x4 CombinedTransform() const {
+ return mTransform * mPerspectiveTransform;
+ }
+
+ bool ContainsPerspectiveTransform() const {
+ return !mPerspectiveTransform.IsIdentity();
+ }
+
+ gfx::Matrix4x4 GetPerspectiveTransform() const {
+ return mPerspectiveTransform;
+ }
+
+ friend AncestorTransform operator*(const AncestorTransform& aA,
+ const AncestorTransform& aB) {
+ return AncestorTransform{
+ aA.mTransform * aB.mTransform,
+ aA.mPerspectiveTransform * aB.mPerspectiveTransform};
+ }
+};
+
+// Flags returned by AsyncPanZoomController::ArePointerEventsConsumable().
+// See the function for more details.
+struct PointerEventsConsumableFlags {
+ // The APZC has room to pan or zoom in response to the touch event.
+ bool mHasRoom = false;
+
+ // The panning or zooming is allowed by the touch-action property.
+ bool mAllowedByTouchAction = false;
+
+ bool IsConsumable() const { return mHasRoom && mAllowedByTouchAction; }
+ friend bool operator==(const PointerEventsConsumableFlags& aLhs,
+ const PointerEventsConsumableFlags& aRhs);
+ friend std::ostream& operator<<(std::ostream& aOut,
+ const PointerEventsConsumableFlags& aFlags);
+};
+
+/**
+ * Controller for all panning and zooming logic. Any time a user input is
+ * detected and it must be processed in some way to affect what the user sees,
+ * it goes through here. Listens for any input event from InputData and can
+ * optionally handle WidgetGUIEvent-derived touch events, but this must be done
+ * on the main thread. Note that this class completely cross-platform.
+ *
+ * Input events originate on the UI thread of the platform that this runs on,
+ * and are then sent to this class. This class processes the event in some way;
+ * for example, a touch move will usually lead to a panning of content (though
+ * of course there are exceptions, such as if content preventDefaults the event,
+ * or if the target frame is not scrollable). The compositor interacts with this
+ * class by locking it and querying it for the current transform matrix based on
+ * the panning and zooming logic that was invoked on the UI thread.
+ *
+ * Currently, each outer DOM window (i.e. a website in a tab, but not any
+ * subframes) has its own AsyncPanZoomController. In the future, to support
+ * asynchronously scrolled subframes, we want to have one AsyncPanZoomController
+ * per frame.
+ */
+class AsyncPanZoomController {
+ NS_INLINE_DECL_THREADSAFE_REFCOUNTING(AsyncPanZoomController)
+
+ typedef mozilla::MonitorAutoLock MonitorAutoLock;
+ typedef mozilla::gfx::Matrix4x4 Matrix4x4;
+ typedef mozilla::layers::RepaintRequest::ScrollOffsetUpdateType
+ RepaintUpdateType;
+
+ public:
+ enum GestureBehavior {
+ // The platform code is responsible for forwarding gesture events here. We
+ // will not attempt to generate gesture events from MultiTouchInputs.
+ DEFAULT_GESTURES,
+ // An instance of GestureEventListener is used to detect gestures. This is
+ // handled completely internally within this class.
+ USE_GESTURE_DETECTOR
+ };
+
+ /**
+ * Gets the DPI from the tree manager.
+ */
+ float GetDPI() const;
+
+ /**
+ * Constant describing the tolerance in distance we use, multiplied by the
+ * device DPI, before we start panning the screen. This is to prevent us from
+ * accidentally processing taps as touch moves, and from very short/accidental
+ * touches moving the screen.
+ * Note: It's an abuse of the 'Coord' class to use it to represent a 2D
+ * distance, but it's the closest thing we currently have.
+ */
+ ScreenCoord GetTouchStartTolerance() const;
+ /**
+ * Same as GetTouchStartTolerance, but the tolerance for how far the touch
+ * has to move before it starts allowing touchmove events to be dispatched
+ * to content, for non-scrollable content.
+ */
+ ScreenCoord GetTouchMoveTolerance() const;
+ /**
+ * Same as GetTouchStartTolerance, but the tolerance for how close the second
+ * tap has to be to the first tap in order to be counted as part of a
+ * multi-tap gesture (double-tap or one-touch-pinch).
+ */
+ ScreenCoord GetSecondTapTolerance() const;
+
+ AsyncPanZoomController(LayersId aLayersId, APZCTreeManager* aTreeManager,
+ const RefPtr<InputQueue>& aInputQueue,
+ GeckoContentController* aController,
+ GestureBehavior aGestures = DEFAULT_GESTURES);
+
+ // --------------------------------------------------------------------------
+ // These methods must only be called on the gecko thread.
+ //
+
+ /**
+ * Read the various prefs and do any global initialization for all APZC
+ * instances. This must be run on the gecko thread before any APZC instances
+ * are actually used for anything meaningful.
+ */
+ static void InitializeGlobalState();
+
+ // --------------------------------------------------------------------------
+ // These methods must only be called on the controller/UI thread.
+ //
+
+ /**
+ * Kicks an animation to zoom to a rect. This may be either a zoom out or zoom
+ * in. The actual animation is done on the sampler thread after being set
+ * up.
+ */
+ void ZoomToRect(const ZoomTarget& aZoomTarget, const uint32_t aFlags);
+
+ /**
+ * Updates any zoom constraints contained in the <meta name="viewport"> tag.
+ */
+ void UpdateZoomConstraints(const ZoomConstraints& aConstraints);
+
+ /**
+ * Schedules a runnable to run on the controller/UI thread at some time
+ * in the future.
+ */
+ void PostDelayedTask(already_AddRefed<Runnable> aTask, int aDelayMs);
+
+ // --------------------------------------------------------------------------
+ // These methods must only be called on the sampler thread.
+ //
+
+ /**
+ * Advances any animations currently running to the given timestamp.
+ * This may be called multiple times with the same timestamp.
+ *
+ * The return value indicates whether or not any currently running animation
+ * should continue. If true, the compositor should schedule another composite.
+ */
+ bool AdvanceAnimations(const SampleTime& aSampleTime);
+
+ bool UpdateAnimation(const RecursiveMutexAutoLock& aProofOfLock,
+ const SampleTime& aSampleTime,
+ nsTArray<RefPtr<Runnable>>* aOutDeferredTasks);
+
+ // --------------------------------------------------------------------------
+ // These methods must only be called on the updater thread.
+ //
+
+ /**
+ * A shadow layer update has arrived. |aScrollMetdata| is the new
+ * ScrollMetadata for the container layer corresponding to this APZC.
+ * |aIsFirstPaint| is a flag passed from the shadow
+ * layers code indicating that the scroll metadata being sent with this call
+ * are the initial metadata and the initial paint of the frame has just
+ * happened.
+ */
+ void NotifyLayersUpdated(const ScrollMetadata& aScrollMetadata,
+ bool aIsFirstPaint, bool aThisLayerTreeUpdated);
+
+ /**
+ * The platform implementation must set the compositor controller so that we
+ * can request composites.
+ */
+ void SetCompositorController(CompositorController* aCompositorController);
+
+ // --------------------------------------------------------------------------
+ // These methods can be called from any thread.
+ //
+
+ /**
+ * Shut down the controller/UI thread state and prepare to be
+ * deleted (which may happen from any thread).
+ */
+ void Destroy();
+
+ /**
+ * Returns true if Destroy() has already been called on this APZC instance.
+ */
+ bool IsDestroyed() const;
+
+ /**
+ * Returns the transform to take something from the coordinate space of the
+ * last thing we know gecko painted, to the coordinate space of the last thing
+ * we asked gecko to paint. In cases where that last request has not yet been
+ * processed, this is needed to transform input events properly into a space
+ * gecko will understand.
+ */
+ Matrix4x4 GetTransformToLastDispatchedPaint(
+ const AsyncTransformComponents& aComponents = LayoutAndVisual) const;
+
+ /**
+ * Returns the number of CSS pixels of checkerboard according to the metrics
+ * in this APZC. The argument provided by the caller is the composition bounds
+ * of this APZC, additionally clipped by the composition bounds of any
+ * ancestor APZCs, accounting for all the async transforms.
+ */
+ uint32_t GetCheckerboardMagnitude(
+ const ParentLayerRect& aClippedCompositionBounds) const;
+
+ /**
+ * Report the number of CSSPixel-milliseconds of checkerboard to telemetry.
+ * See GetCheckerboardMagnitude for documentation of the
+ * aClippedCompositionBounds argument that needs to be provided by the caller.
+ */
+ void ReportCheckerboard(const SampleTime& aSampleTime,
+ const ParentLayerRect& aClippedCompositionBounds);
+
+ /**
+ * Flush any active checkerboard report that's in progress. This basically
+ * pretends like any in-progress checkerboard event has terminated, and pushes
+ * out the report to the checkerboard reporting service and telemetry. If the
+ * checkerboard event has not really finished, it will start a new event
+ * on the next composite.
+ */
+ void FlushActiveCheckerboardReport();
+
+ /**
+ * See documentation on corresponding method in APZPublicUtils.h
+ */
+ static gfx::IntSize GetDisplayportAlignmentMultiplier(
+ const ScreenSize& aBaseSize);
+
+ enum class ZoomInProgress {
+ No,
+ Yes,
+ };
+
+ /**
+ * Recalculates the displayport. Ideally, this should paint an area bigger
+ * than the composite-to dimensions so that when you scroll down, you don't
+ * checkerboard immediately. This includes a bunch of logic, including
+ * algorithms to bias painting in the direction of the velocity and other
+ * such things.
+ */
+ static const ScreenMargin CalculatePendingDisplayPort(
+ const FrameMetrics& aFrameMetrics, const ParentLayerPoint& aVelocity,
+ ZoomInProgress aZoomInProgress);
+
+ nsEventStatus HandleDragEvent(const MouseInput& aEvent,
+ const AsyncDragMetrics& aDragMetrics,
+ OuterCSSCoord aInitialThumbPos);
+
+ /**
+ * Handler for events which should not be intercepted by the touch listener.
+ */
+ nsEventStatus HandleInputEvent(
+ const InputData& aEvent,
+ const ScreenToParentLayerMatrix4x4& aTransformToApzc);
+
+ /**
+ * Handler for gesture events.
+ * Currently some gestures are detected in GestureEventListener that calls
+ * APZC back through this handler in order to avoid recursive calls to
+ * APZC::HandleInputEvent() which is supposed to do the work for
+ * ReceiveInputEvent().
+ */
+ nsEventStatus HandleGestureEvent(const InputData& aEvent);
+
+ /**
+ * Start autoscrolling this APZC, anchored at the provided location.
+ */
+ void StartAutoscroll(const ScreenPoint& aAnchorLocation);
+
+ /**
+ * Stop autoscrolling this APZC.
+ */
+ void StopAutoscroll();
+
+ /**
+ * Populates the provided object (if non-null) with the scrollable guid of
+ * this apzc.
+ */
+ void GetGuid(ScrollableLayerGuid* aGuidOut) const;
+
+ /**
+ * Returns the scrollable guid of this apzc.
+ */
+ ScrollableLayerGuid GetGuid() const;
+
+ /**
+ * Returns true if this APZC instance is for the layer identified by the guid.
+ */
+ bool Matches(const ScrollableLayerGuid& aGuid);
+
+ /**
+ * Returns true if the tree manager of this APZC is the same as the one
+ * passed in.
+ */
+ bool HasTreeManager(const APZCTreeManager* aTreeManager) const;
+
+ void StartAnimation(AsyncPanZoomAnimation* aAnimation);
+
+ /**
+ * Cancels any currently running animation.
+ * aFlags is a bit-field to provide specifics of how to cancel the animation.
+ * See CancelAnimationFlags.
+ */
+ void CancelAnimation(CancelAnimationFlags aFlags = Default);
+
+ /**
+ * Clear any overscroll on this APZC.
+ */
+ void ClearOverscroll();
+ void ClearPhysicalOverscroll();
+
+ /**
+ * Returns whether this APZC is for an element marked with the 'scrollgrab'
+ * attribute.
+ */
+ bool HasScrollgrab() const { return mScrollMetadata.GetHasScrollgrab(); }
+
+ /**
+ * Returns whether this APZC has scroll snap points.
+ */
+ bool HasScrollSnapping() const {
+ return mScrollMetadata.GetSnapInfo().HasScrollSnapping();
+ }
+
+ /**
+ * Returns whether this APZC has room to be panned (in any direction).
+ */
+ bool IsPannable() const;
+
+ /**
+ * Returns whether this APZC represents a scroll info layer.
+ */
+ bool IsScrollInfoLayer() const;
+
+ /**
+ * Returns true if the APZC has been flung with a velocity greater than the
+ * stop-on-tap fling velocity threshold (which is pref-controlled).
+ */
+ bool IsFlingingFast() const;
+
+ /**
+ * Returns whether this APZC is currently autoscrolling.
+ */
+ bool IsAutoscroll() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mState == AUTOSCROLL;
+ }
+
+ /**
+ * Returns the identifier of the touch in the last touch event processed by
+ * this APZC. This should only be called when the last touch event contained
+ * only one touch.
+ */
+ int32_t GetLastTouchIdentifier() const;
+
+ /**
+ * Returns the matrix that transforms points from global screen space into
+ * this APZC's ParentLayer space.
+ * To respect the lock ordering, mRecursiveMutex must NOT be held when calling
+ * this function (since this function acquires the tree lock).
+ */
+ ScreenToParentLayerMatrix4x4 GetTransformToThis() const;
+
+ /**
+ * Convert the vector |aVector|, rooted at the point |aAnchor|, from
+ * this APZC's ParentLayer coordinates into screen coordinates.
+ * The anchor is necessary because with 3D tranforms, the location of the
+ * vector can affect the result of the transform.
+ * To respect the lock ordering, mRecursiveMutex must NOT be held when calling
+ * this function (since this function acquires the tree lock).
+ */
+ ScreenPoint ToScreenCoordinates(const ParentLayerPoint& aVector,
+ const ParentLayerPoint& aAnchor) const;
+
+ /**
+ * Convert the vector |aVector|, rooted at the point |aAnchor|, from
+ * screen coordinates into this APZC's ParentLayer coordinates.
+ * The anchor is necessary because with 3D tranforms, the location of the
+ * vector can affect the result of the transform.
+ * To respect the lock ordering, mRecursiveMutex must NOT be held when calling
+ * this function (since this function acquires the tree lock).
+ */
+ ParentLayerPoint ToParentLayerCoordinates(const ScreenPoint& aVector,
+ const ScreenPoint& aAnchor) const;
+
+ /**
+ * Same as above, but uses an ExternalPoint as the anchor.
+ */
+ ParentLayerPoint ToParentLayerCoordinates(const ScreenPoint& aVector,
+ const ExternalPoint& aAnchor) const;
+
+ /**
+ * Combines an offset defined as an external point, with a window-relative
+ * offset to give an absolute external point.
+ */
+ static ExternalPoint ToExternalPoint(const ExternalPoint& aScreenOffset,
+ const ScreenPoint& aScreenPoint);
+
+ /**
+ * Gets a vector where the head is the given point, and the tail is
+ * the touch start position.
+ */
+ ScreenPoint PanVector(const ExternalPoint& aPos) const;
+
+ // Return whether or not a wheel event will be able to scroll in either
+ // direction.
+ bool CanScroll(const InputData& aEvent) const;
+
+ // Return the directions in which this APZC allows handoff (as governed by
+ // overscroll-behavior).
+ ScrollDirections GetAllowedHandoffDirections() const;
+
+ // Return the directions in which this APZC allows overscrolling.
+ ScrollDirections GetOverscrollableDirections() const;
+
+ // Return whether or not a scroll delta will be able to scroll in either
+ // direction.
+ bool CanScroll(const ParentLayerPoint& aDelta) const;
+
+ // Return whether or not a scroll delta will be able to scroll in either
+ // direction with wheel.
+ bool CanScrollWithWheel(const ParentLayerPoint& aDelta) const;
+
+ // Return whether or not there is room to scroll this APZC
+ // in the given direction.
+ bool CanScroll(ScrollDirection aDirection) const;
+
+ // Return the directions in which this APZC is able to scroll.
+ SideBits ScrollableDirections() const;
+
+ // Return true if there is room to scroll along with moving the dynamic
+ // toolbar.
+ //
+ // NOTE: This function should be used only for the root content APZC.
+ bool CanVerticalScrollWithDynamicToolbar() const;
+
+ // Return true if there is room to scroll downwards.
+ bool CanScrollDownwards() const;
+
+ /**
+ * Convert a point on the scrollbar from this APZC's ParentLayer coordinates
+ * to OuterCSS coordinates relative to the beginning of the scroll track.
+ * Only the component in the direction of scrolling is returned.
+ */
+ OuterCSSCoord ConvertScrollbarPoint(const ParentLayerPoint& aScrollbarPoint,
+ const ScrollbarData& aThumbData) const;
+
+ void NotifyMozMouseScrollEvent(const nsString& aString) const;
+
+ bool OverscrollBehaviorAllowsSwipe() const;
+
+ //|Metrics()| and |Metrics() const| are getter functions that both return
+ // mScrollMetadata.mMetrics
+
+ const FrameMetrics& Metrics() const;
+ FrameMetrics& Metrics();
+
+ /**
+ * Get the GeckoViewMetrics to be sent to Gecko for the current composite.
+ */
+ GeckoViewMetrics GetGeckoViewMetrics() const;
+
+ // Helper function to compare root frame metrics and update them
+ // Returns true when the metrics have changed and were updated.
+ bool UpdateRootFrameMetricsIfChanged(GeckoViewMetrics& aMetrics);
+
+ // Returns the cached current frame time.
+ SampleTime GetFrameTime() const;
+
+ bool IsZero(const ParentLayerPoint& aPoint) const;
+ bool IsZero(ParentLayerCoord aCoord) const;
+
+ bool FuzzyGreater(ParentLayerCoord aCoord1, ParentLayerCoord aCoord2) const;
+
+ private:
+ // Get whether the horizontal content of the honoured target of auto-dir
+ // scrolling starts from right to left. If you don't know of auto-dir
+ // scrolling or what a honoured target means,
+ // @see mozilla::WheelDeltaAdjustmentStrategy
+ bool IsContentOfHonouredTargetRightToLeft(bool aHonoursRoot) const;
+
+ protected:
+ // Protected destructor, to discourage deletion outside of Release():
+ virtual ~AsyncPanZoomController();
+
+ /**
+ * Helper method for touches beginning. Sets everything up for panning and any
+ * multitouch gestures.
+ */
+ nsEventStatus OnTouchStart(const MultiTouchInput& aEvent);
+
+ /**
+ * Helper method for touches moving. Does any transforms needed when panning.
+ */
+ nsEventStatus OnTouchMove(const MultiTouchInput& aEvent);
+
+ /**
+ * Helper method for touches ending. Redraws the screen if necessary and does
+ * any cleanup after a touch has ended.
+ */
+ nsEventStatus OnTouchEnd(const MultiTouchInput& aEvent);
+
+ /**
+ * Helper method for touches being cancelled. Treated roughly the same as a
+ * touch ending (OnTouchEnd()).
+ */
+ nsEventStatus OnTouchCancel(const MultiTouchInput& aEvent);
+
+ /**
+ * Helper method for scales beginning. Distinct from the OnTouch* handlers in
+ * that this implies some outside implementation has determined that the user
+ * is pinching.
+ */
+ nsEventStatus OnScaleBegin(const PinchGestureInput& aEvent);
+
+ /**
+ * Helper method for scaling. As the user moves their fingers when pinching,
+ * this changes the scale of the page.
+ */
+ nsEventStatus OnScale(const PinchGestureInput& aEvent);
+
+ /**
+ * Helper method for scales ending. Redraws the screen if necessary and does
+ * any cleanup after a scale has ended.
+ */
+ nsEventStatus OnScaleEnd(const PinchGestureInput& aEvent);
+
+ /**
+ * Helper methods for handling pan events.
+ */
+ nsEventStatus OnPanMayBegin(const PanGestureInput& aEvent);
+ nsEventStatus OnPanCancelled(const PanGestureInput& aEvent);
+ nsEventStatus OnPanBegin(const PanGestureInput& aEvent);
+ enum class FingersOnTouchpad {
+ Yes,
+ No,
+ };
+ nsEventStatus OnPan(const PanGestureInput& aEvent,
+ FingersOnTouchpad aFingersOnTouchpad);
+ nsEventStatus OnPanEnd(const PanGestureInput& aEvent);
+ nsEventStatus OnPanMomentumStart(const PanGestureInput& aEvent);
+ nsEventStatus OnPanMomentumEnd(const PanGestureInput& aEvent);
+ nsEventStatus HandleEndOfPan();
+ nsEventStatus OnPanInterrupted(const PanGestureInput& aEvent);
+
+ /**
+ * Helper methods for handling scroll wheel events.
+ */
+ nsEventStatus OnScrollWheel(const ScrollWheelInput& aEvent);
+
+ /**
+ * Gets the scroll wheel delta's values in parent-layer pixels from the
+ * original delta's values of a wheel input.
+ */
+ ParentLayerPoint GetScrollWheelDelta(const ScrollWheelInput& aEvent) const;
+
+ /**
+ * This function is like GetScrollWheelDelta(aEvent).
+ * The difference is the four added parameters provide values as alternatives
+ * to the original wheel input's delta values, so |aEvent|'s delta values are
+ * ignored in this function, we only use some other member variables and
+ * functions of |aEvent|.
+ */
+ ParentLayerPoint GetScrollWheelDelta(const ScrollWheelInput& aEvent,
+ double aDeltaX, double aDeltaY,
+ double aMultiplierX,
+ double aMultiplierY) const;
+
+ /**
+ * This deleted function is used for:
+ * 1. avoiding accidental implicit value type conversions of input delta
+ * values when callers intend to call the above function;
+ * 2. decoupling the manual relationship between the delta value type and the
+ * above function. If by any chance the defined delta value type in
+ * ScrollWheelInput has changed, this will automatically result in build
+ * time failure, so we can learn of it the first time and accordingly
+ * redefine those parameters' value types in the above function.
+ */
+ template <typename T>
+ ParentLayerPoint GetScrollWheelDelta(ScrollWheelInput&, T, T, T, T) = delete;
+
+ /**
+ * Helper methods for handling keyboard events.
+ */
+ nsEventStatus OnKeyboard(const KeyboardInput& aEvent);
+
+ CSSPoint GetKeyboardDestination(const KeyboardScrollAction& aAction) const;
+
+ // Returns the corresponding ScrollSnapFlags for the given |aAction|.
+ // See https://drafts.csswg.org/css-scroll-snap/#scroll-types
+ ScrollSnapFlags GetScrollSnapFlagsForKeyboardAction(
+ const KeyboardScrollAction& aAction) const;
+
+ /**
+ * Helper methods for long press gestures.
+ */
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY
+ nsEventStatus OnLongPress(const TapGestureInput& aEvent);
+ nsEventStatus OnLongPressUp(const TapGestureInput& aEvent);
+
+ /**
+ * Helper method for single tap gestures.
+ */
+ nsEventStatus OnSingleTapUp(const TapGestureInput& aEvent);
+
+ /**
+ * Helper method for a single tap confirmed.
+ */
+ nsEventStatus OnSingleTapConfirmed(const TapGestureInput& aEvent);
+
+ /**
+ * Helper method for double taps.
+ */
+ MOZ_CAN_RUN_SCRIPT_BOUNDARY
+ nsEventStatus OnDoubleTap(const TapGestureInput& aEvent);
+
+ /**
+ * Helper method for double taps where the double-tap gesture is disabled.
+ */
+ nsEventStatus OnSecondTap(const TapGestureInput& aEvent);
+
+ /**
+ * Helper method to cancel any gesture currently going to Gecko. Used
+ * primarily when a user taps the screen over some clickable content but then
+ * pans down instead of letting go (i.e. to cancel a previous touch so that a
+ * new one can properly take effect.
+ */
+ nsEventStatus OnCancelTap(const TapGestureInput& aEvent);
+
+ /**
+ * The following five methods modify the scroll offset. For the APZC
+ * representing the RCD-RSF, they also recalculate the offset of the layout
+ * viewport.
+ */
+
+ /**
+ * Scroll the scroll frame to an X,Y offset.
+ */
+ void SetVisualScrollOffset(const CSSPoint& aOffset);
+
+ /**
+ * Scroll the scroll frame to an X,Y offset, clamping the resulting scroll
+ * offset to the scroll range.
+ */
+ void ClampAndSetVisualScrollOffset(const CSSPoint& aOffset);
+
+ /**
+ * Scroll the scroll frame by an X,Y offset.
+ * The resulting scroll offset is not clamped to the scrollable rect;
+ * the caller must ensure it stays within range.
+ */
+ void ScrollBy(const CSSPoint& aOffset);
+
+ /**
+ * Scroll the scroll frame by an X,Y offset, clamping the resulting
+ * scroll offset to the scroll range.
+ */
+ void ScrollByAndClamp(const CSSPoint& aOffset);
+
+ /**
+ * Scales the viewport by an amount (note that it multiplies this scale in to
+ * the current scale, it doesn't set it to |aScale|). Also considers a focus
+ * point so that the page zooms inward/outward from that point.
+ */
+ void ScaleWithFocus(float aScale, const CSSPoint& aFocus);
+
+ /**
+ * Schedules a composite on the compositor thread.
+ */
+ void ScheduleComposite();
+
+ /**
+ * Schedules a composite, and if enough time has elapsed since the last
+ * paint, a paint.
+ */
+ void ScheduleCompositeAndMaybeRepaint();
+
+ /**
+ * Gets the start point of the current touch.
+ * This only makes sense if a touch is currently happening and OnTouchMove()
+ * or the equivalent for pan gestures is being invoked.
+ */
+ ParentLayerPoint PanStart() const;
+
+ /**
+ * Gets a vector of the velocities of each axis.
+ */
+ const ParentLayerPoint GetVelocityVector() const;
+
+ /**
+ * Sets the velocities of each axis.
+ */
+ void SetVelocityVector(const ParentLayerPoint& aVelocityVector);
+
+ /**
+ * Gets the first touch point from a MultiTouchInput. This gets only
+ * the first one and assumes the rest are either missing or not relevant.
+ */
+ ParentLayerPoint GetFirstTouchPoint(const MultiTouchInput& aEvent);
+
+ /**
+ * Gets the relevant point in the event
+ * (eg. first touch, or pinch focus point) of the given InputData.
+ */
+ ExternalPoint GetExternalPoint(const InputData& aEvent);
+
+ /**
+ * Gets the relevant point in the event, in external screen coordinates.
+ */
+ ExternalPoint GetFirstExternalTouchPoint(const MultiTouchInput& aEvent);
+
+ /**
+ * Gets the amount by which this APZC is overscrolled along both axes.
+ */
+ ParentLayerPoint GetOverscrollAmount() const;
+
+ private:
+ // Internal version of GetOverscrollAmount() which does not set
+ // the test async properties.
+ ParentLayerPoint GetOverscrollAmountInternal() const;
+
+ protected:
+ /**
+ * Returns SideBits where this APZC is overscrolled.
+ */
+ SideBits GetOverscrollSideBits() const;
+
+ /**
+ * Restore the amount by which this APZC is overscrolled along both axes
+ * to the specified amount. This is for test-related use; overscrolling
+ * as a result of user input should happen via OverscrollBy().
+ */
+ void RestoreOverscrollAmount(const ParentLayerPoint& aOverscroll);
+
+ /**
+ * Sets the panning state basing on the pan direction angle and current
+ * touch-action value.
+ */
+ void HandlePanningWithTouchAction(double angle);
+
+ /**
+ * Sets the panning state ignoring the touch action value.
+ */
+ void HandlePanning(double angle);
+
+ /**
+ * Update the panning state and axis locks.
+ */
+ void HandlePanningUpdate(const ScreenPoint& aDelta);
+
+ /**
+ * Set and update the pinch lock
+ */
+ void HandlePinchLocking(const PinchGestureInput& aEvent);
+
+ /**
+ * Sets up anything needed for panning. This takes us out of the "TOUCHING"
+ * state and starts actually panning us. We provide the physical pixel
+ * position of the start point so that the pan gesture is calculated
+ * regardless of if the window/GeckoView moved during the pan.
+ */
+ nsEventStatus StartPanning(const ExternalPoint& aStartPoint,
+ const TimeStamp& aEventTime);
+
+ /**
+ * Wrapper for Axis::UpdateWithTouchAtDevicePoint(). Calls this function for
+ * both axes and factors in the time delta from the last update.
+ */
+ void UpdateWithTouchAtDevicePoint(const MultiTouchInput& aEvent);
+
+ /**
+ * Does any panning required due to a new touch event.
+ */
+ void TrackTouch(const MultiTouchInput& aEvent);
+
+ /**
+ * Register the start of a touch or pan gesture at the given position and
+ * time.
+ */
+ void StartTouch(const ParentLayerPoint& aPoint, TimeStamp aTimestamp);
+
+ /**
+ * Register the end of a touch or pan gesture at the given time.
+ */
+ void EndTouch(TimeStamp aTimestamp, Axis::ClearAxisLock aClearAxisLock);
+
+ /**
+ * Utility function to send updated FrameMetrics to Gecko so that it can paint
+ * the displayport area. Calls into GeckoContentController to do the actual
+ * work. This call will use the current metrics. If this function is called
+ * from a non-main thread, it will redispatch itself to the main thread, and
+ * use the latest metrics during the redispatch.
+ */
+ void RequestContentRepaint(
+ RepaintUpdateType aUpdateType = RepaintUpdateType::eUserAction);
+
+ /**
+ * Send Metrics() to Gecko to trigger a repaint. This function may filter
+ * duplicate calls with the same metrics. This function must be called on the
+ * main thread.
+ */
+ void RequestContentRepaint(const ParentLayerPoint& aVelocity,
+ const ScreenMargin& aDisplayportMargins,
+ RepaintUpdateType aUpdateType);
+
+ /**
+ * Gets the current frame metrics. This is *not* the Gecko copy stored in the
+ * layers code.
+ */
+ const FrameMetrics& GetFrameMetrics() const;
+
+ /**
+ * Gets the current scroll metadata. This is *not* the Gecko copy stored in
+ * the layers code/
+ */
+ const ScrollMetadata& GetScrollMetadata() const;
+
+ /**
+ * Gets the pointer to the apzc tree manager. All the access to tree manager
+ * should be made via this method and not via private variable since this
+ * method ensures that no lock is set.
+ */
+ APZCTreeManager* GetApzcTreeManager() const;
+
+ void AssertOnSamplerThread() const;
+ void AssertOnUpdaterThread() const;
+
+ /**
+ * Convert ScreenPoint relative to the screen to LayoutDevicePoint relative
+ * to the parent document. This excludes the transient compositor transform.
+ * NOTE: This must be converted to LayoutDevicePoint relative to the child
+ * document before sending over IPC to a child process.
+ */
+ Maybe<LayoutDevicePoint> ConvertToGecko(const ScreenIntPoint& aPoint);
+
+ enum AxisLockMode {
+ FREE, /* No locking at all */
+ STANDARD, /* Default axis locking mode that remains locked until pan ends */
+ STICKY, /* Allow lock to be broken, with hysteresis */
+ DOMINANT_AXIS, /* Only allow movement on one axis */
+ };
+
+ static AxisLockMode GetAxisLockMode();
+
+ bool UsingStatefulAxisLock() const;
+
+ enum PinchLockMode {
+ PINCH_FREE, /* No locking at all */
+ PINCH_STANDARD, /* Default pinch locking mode that remains locked until
+ pinch gesture ends*/
+ PINCH_STICKY, /* Allow lock to be broken, with hysteresis */
+ };
+
+ static PinchLockMode GetPinchLockMode();
+
+ // Helper function for OnSingleTapUp(), OnSingleTapConfirmed(), and
+ // OnLongPressUp().
+ nsEventStatus GenerateSingleTap(GeckoContentController::TapType aType,
+ const ScreenIntPoint& aPoint,
+ mozilla::Modifiers aModifiers);
+
+ // Common processing at the end of a touch block.
+ void OnTouchEndOrCancel();
+
+ LayersId mLayersId;
+ RefPtr<CompositorController> mCompositorController;
+
+ /* Access to the following two fields is protected by the mRefPtrMonitor,
+ since they are accessed on the UI thread but can be cleared on the
+ updater thread. */
+ RefPtr<GeckoContentController> mGeckoContentController;
+ RefPtr<GestureEventListener> mGestureEventListener;
+ mutable Monitor mRefPtrMonitor MOZ_UNANNOTATED;
+
+ // This is a raw pointer to avoid introducing a reference cycle between
+ // AsyncPanZoomController and APZCTreeManager. Since these objects don't
+ // live on the main thread, we can't use the cycle collector with them.
+ // The APZCTreeManager owns the lifetime of the APZCs, so nulling this
+ // pointer out in Destroy() will prevent accessing deleted memory.
+ Atomic<APZCTreeManager*> mTreeManager;
+
+ /* Utility functions that return a addrefed pointer to the corresponding
+ * fields. */
+ already_AddRefed<GeckoContentController> GetGeckoContentController() const;
+ already_AddRefed<GestureEventListener> GetGestureEventListener() const;
+
+ PlatformSpecificStateBase* GetPlatformSpecificState();
+
+ /**
+ * Convenience functions to get the corresponding fields of mZoomContraints
+ * while holding mRecursiveMutex.
+ */
+ bool ZoomConstraintsAllowZoom() const;
+ bool ZoomConstraintsAllowDoubleTapZoom() const;
+
+ protected:
+ // Both |mScrollMetadata| and |mLastContentPaintMetrics| are protected by the
+ // monitor. Do not read from or modify them without locking.
+ ScrollMetadata mScrollMetadata;
+
+ // Protects |mScrollMetadata|, |mLastContentPaintMetrics|, |mState| and
+ // |mLastSnapTargetIds|. Before manipulating |mScrollMetadata|,
+ // |mLastContentPaintMetrics| or |mLastSnapTargetIds| the monitor should be
+ // held. When setting |mState|, either the SetState() function can be used, or
+ // the monitor can be held and then |mState| updated.
+ // IMPORTANT: See the note about lock ordering at the top of
+ // APZCTreeManager.h. This is mutable to allow entering it from 'const'
+ // methods; doing otherwise would significantly limit what methods could be
+ // 'const'.
+ // FIXME: Please keep in mind that due to some existing coupled relationships
+ // among the class members, we should be aware of indirect usage of the
+ // monitor-protected members. That is, although this monitor isn't required to
+ // be held before manipulating non-protected class members, some functions on
+ // those members might indirectly manipulate the protected members; in such
+ // cases, the monitor should still be held. Let's take mX.CanScroll for
+ // example:
+ // Axis::CanScroll(ParentLayerCoord) calls Axis::CanScroll() which calls
+ // Axis::GetPageLength() which calls Axis::GetFrameMetrics() which calls
+ // AsyncPanZoomController::GetFrameMetrics(), therefore, this monitor should
+ // be held before calling the CanScroll function of |mX| and |mY|. These
+ // coupled relationships bring us the burden of taking care of when the
+ // monitor should be held, so they should be decoupled in the future.
+ mutable RecursiveMutex mRecursiveMutex MOZ_UNANNOTATED;
+
+ private:
+ // Metadata of the container layer corresponding to this APZC. This is
+ // stored here so that it is accessible from the UI/controller thread.
+ // These are the metrics at last content paint, the most recent
+ // values we were notified of in NotifyLayersUpdate(). Since it represents
+ // the Gecko state, it should be used as a basis for untransformation when
+ // sending messages back to Gecko.
+ ScrollMetadata mLastContentPaintMetadata;
+ FrameMetrics& mLastContentPaintMetrics; // for convenience, refers to
+ // mLastContentPaintMetadata.mMetrics
+ // The last content repaint request.
+ RepaintRequest mLastPaintRequestMetrics;
+ // The metrics that we expect content to have. This is updated when we
+ // request a content repaint, and when we receive a shadow layers update.
+ // This allows us to transform events into Gecko's coordinate space.
+ ExpectedGeckoMetrics mExpectedGeckoMetrics;
+
+ // This holds important state from the Metrics() at previous times
+ // SampleCompositedAsyncTransform() was called. This will always have at least
+ // one item. mRecursiveMutex must be held when using or modifying this member.
+ // Samples should be inserted to the "back" of the deque and extracted from
+ // the "front".
+ std::deque<SampledAPZCState> mSampledState;
+
+ // Groups state variables that are specific to a platform.
+ // Initialized on first use.
+ UniquePtr<PlatformSpecificStateBase> mPlatformSpecificState;
+
+ // This flag is set to true when we are in a axis-locked pan as a result of
+ // the touch-action CSS property.
+ bool mPanDirRestricted;
+
+ // This flag is set to true when we are in a pinch-locked state. ie: user
+ // is performing a two-finger pan rather than a pinch gesture
+ bool mPinchLocked;
+
+ // Stores the pinch events that occured within a given timeframe. Used to
+ // calculate the focusChange and spanDistance within a fixed timeframe.
+ // RecentEventsBuffer is not threadsafe. Should only be accessed on the
+ // controller thread.
+ RecentEventsBuffer<PinchGestureInput> mPinchEventBuffer;
+
+ // Most up-to-date constraints on zooming. These should always be reasonable
+ // values; for example, allowing a min zoom of 0.0 can cause very bad things
+ // to happen. Hold mRecursiveMutex when accessing this.
+ ZoomConstraints mZoomConstraints;
+
+ // The last time the compositor has sampled the content transform for this
+ // frame.
+ SampleTime mLastSampleTime;
+
+ // The last sample time at which we submitted a checkerboarding report.
+ SampleTime mLastCheckerboardReport;
+
+ // Stores the previous focus point if there is a pinch gesture happening. Used
+ // to allow panning by moving multiple fingers (thus moving the focus point).
+ ParentLayerPoint mLastZoomFocus;
+
+ // Stores the previous zoom level at which we last sent a ScaleGestureComplete
+ // notification.
+ CSSToParentLayerScale mLastNotifiedZoom;
+
+ // Accessing mAnimation needs to be protected by mRecursiveMutex
+ RefPtr<AsyncPanZoomAnimation> mAnimation;
+
+ UniquePtr<OverscrollEffectBase> mOverscrollEffect;
+
+ // Zoom animation id, used for zooming in WebRender. This should only be
+ // set on the APZC instance for the root content document (i.e. the one we
+ // support zooming on), and is only used if WebRender is enabled. The
+ // animation id itself refers to the transform animation id that was set on
+ // the stacking context in the WR display list. By changing the transform
+ // associated with this id, we can adjust the scaling that WebRender applies,
+ // thereby controlling the zoom.
+ Maybe<uint64_t> mZoomAnimationId;
+
+ // Position on screen where user first put their finger down.
+ ExternalPoint mStartTouch;
+
+ // Accessing mScrollPayload needs to be protected by mRecursiveMutex
+ Maybe<CompositionPayload> mScrollPayload;
+
+ // Representing sampled scroll offset generation, this value is bumped up
+ // every time this APZC sampled new scroll offset.
+ APZScrollGeneration mScrollGeneration;
+
+ friend class Axis;
+
+ public:
+ Maybe<CompositionPayload> NotifyScrollSampling();
+
+ /**
+ * Invoke |callable|, passing |mLastContentPaintMetrics| as argument,
+ * while holding the APZC lock required to access |mLastContentPaintMetrics|.
+ * This allows code outside of an AsyncPanZoomController method implementation
+ * to access |mLastContentPaintMetrics| without having to make a copy of it.
+ * Passes through the return value of |callable|.
+ */
+ template <typename Callable>
+ auto CallWithLastContentPaintMetrics(const Callable& callable) const
+ -> decltype(callable(mLastContentPaintMetrics)) {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return callable(mLastContentPaintMetrics);
+ }
+
+ void SetZoomAnimationId(const Maybe<uint64_t>& aZoomAnimationId);
+ Maybe<uint64_t> GetZoomAnimationId() const;
+
+ /* ===================================================================
+ * The functions and members in this section are used to expose
+ * the current async transform state to callers.
+ */
+ public:
+ /**
+ * Allows consumers of async transforms to specify for what purpose they are
+ * using the async transform:
+ *
+ * |eForHitTesting| is intended for hit-testing and other uses that need
+ * the most up-to-date transform, reflecting all events
+ * that have been processed so far, even if the transform
+ * is not yet reflected visually.
+ * |eForCompositing| is intended for the transform that should be reflected
+ * visually.
+ *
+ * For example, if an APZC has metrics with the mForceDisableApz flag set,
+ * then the |eForCompositing| async transform will be empty, while the
+ * |eForHitTesting| async transform will reflect processed input events
+ * regardless of mForceDisableApz.
+ */
+ enum AsyncTransformConsumer {
+ eForHitTesting,
+ eForCompositing,
+ };
+
+ /**
+ * Get the current scroll offset of the scrollable frame corresponding
+ * to this APZC, including the effects of any asynchronous panning and
+ * zooming, in ParentLayer pixels.
+ */
+ ParentLayerPoint GetCurrentAsyncScrollOffset(
+ AsyncTransformConsumer aMode) const;
+
+ /**
+ * Get the current visual viewport of the scrollable frame corresponding
+ * to this APZC, including the effects of any asynchronous panning and
+ * zooming, in CSS pixels.
+ */
+ CSSRect GetCurrentAsyncVisualViewport(AsyncTransformConsumer aMode) const;
+
+ /**
+ * Return a visual effect that reflects this apzc's
+ * overscrolled state, if any.
+ */
+ AsyncTransformComponentMatrix GetOverscrollTransform(
+ AsyncTransformConsumer aMode) const;
+
+ /**
+ * Returns the incremental transformation corresponding to the async pan/zoom
+ * in progress. That is, when this transform is multiplied with the layer's
+ * existing transform, it will make the layer appear with the desired pan/zoom
+ * amount.
+ * The transform can have both scroll and zoom components; the caller can
+ * request just one or the other, or both, via the |aComponents| parameter.
+ * When only the eLayout component is requested, the returned translation
+ * should really be a LayerPoint, rather than a ParentLayerPoint, as it will
+ * not be scaled by the asynchronous zoom.
+ * |aMode| specifies whether the async transform is queried for the purpose of
+ * hit testing (eHitTesting) in which case the latest values from |Metrics()|
+ * are used, or for compositing (eCompositing) in which case a sampled value
+ * from |mSampledState| is used.
+ * |aSampleIndex| specifies which sample in |mSampledState| to use.
+ */
+ AsyncTransform GetCurrentAsyncTransform(
+ AsyncTransformConsumer aMode,
+ AsyncTransformComponents aComponents = LayoutAndVisual,
+ std::size_t aSampleIndex = 0) const;
+
+ /**
+ * Returns the same transform as GetCurrentAsyncTransform(), but includes
+ * any transform due to axis over-scroll.
+ */
+ AsyncTransformComponentMatrix GetCurrentAsyncTransformWithOverscroll(
+ AsyncTransformConsumer aMode,
+ AsyncTransformComponents aComponents = LayoutAndVisual,
+ std::size_t aSampleIndex = 0) const;
+
+ AutoTArray<wr::SampledScrollOffset, 2> GetSampledScrollOffsets() const;
+
+ /**
+ * Returns the "zoom" bits of the transform. This includes both the rasterized
+ * (layout device to layer scale) and async (layer scale to parent layer
+ * scale) components of the zoom.
+ */
+ LayoutDeviceToParentLayerScale GetCurrentPinchZoomScale(
+ AsyncTransformConsumer aMode) const;
+
+ ParentLayerRect GetCompositionBounds() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mScrollMetadata.GetMetrics().GetCompositionBounds();
+ }
+
+ LayoutDeviceToLayerScale GetCumulativeResolution() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mScrollMetadata.GetMetrics().GetCumulativeResolution();
+ }
+
+ // Returns the delta for the given InputData.
+ ParentLayerPoint GetDeltaForEvent(const InputData& aEvent) const;
+
+ /**
+ * Get the current scroll range of the scrollable frame coreesponding to this
+ * APZC.
+ */
+ CSSRect GetCurrentScrollRangeInCssPixels() const;
+
+ private:
+ /**
+ * Advances to the next sample, if there is one, the list of sampled states
+ * stored in mSampledState. This will make the result of
+ * |GetCurrentAsyncTransform(eForCompositing)| and similar functions reflect
+ * the async scroll offset and zoom of the next sample. See also
+ * SampleCompositedAsyncTransform which creates the samples.
+ */
+ void AdvanceToNextSample();
+
+ /**
+ * Samples the composited async transform, storing the result into
+ * mSampledState. This will make the result of
+ * |GetCurrentAsyncTransform(eForCompositing)| and similar functions reflect
+ * the async scroll offset and zoom stored in |Metrics()| when the sample
+ * is activated via some future call to |AdvanceToNextSample|.
+ *
+ * Returns true if the newly sampled value is different from the last
+ * sampled value.
+ */
+ bool SampleCompositedAsyncTransform(
+ const RecursiveMutexAutoLock& aProofOfLock);
+
+ /**
+ * Updates the sample at the front of mSampledState with the latest
+ * metrics. This makes the result of
+ * |GetCurrentAsyncTransform(eForCompositing)| reflect the current Metrics().
+ */
+ void ResampleCompositedAsyncTransform(
+ const RecursiveMutexAutoLock& aProofOfLock);
+
+ /*
+ * Helper functions to query the async layout viewport, scroll offset, and
+ * zoom either directly from |Metrics()|, or from cached variables that
+ * store the required value from the last time it was sampled by calling
+ * SampleCompositedAsyncTransform(), depending on who is asking.
+ */
+ CSSRect GetEffectiveLayoutViewport(AsyncTransformConsumer aMode,
+ const RecursiveMutexAutoLock& aProofOfLock,
+ std::size_t aSampleIndex = 0) const;
+ CSSPoint GetEffectiveScrollOffset(AsyncTransformConsumer aMode,
+ const RecursiveMutexAutoLock& aProofOfLock,
+ std::size_t aSampleIndex = 0) const;
+ CSSToParentLayerScale GetEffectiveZoom(
+ AsyncTransformConsumer aMode, const RecursiveMutexAutoLock& aProofOfLock,
+ std::size_t aSampleIndex = 0) const;
+
+ /**
+ * Returns the visible portion of the content scrolled by this APZC, in
+ * CSS pixels. The caller must have acquired the mRecursiveMutex lock.
+ */
+ CSSRect GetVisibleRect(const RecursiveMutexAutoLock& aProofOfLock) const;
+
+ /**
+ * Returns a pair of displacements both in logical/physical units for
+ * |aEvent|.
+ */
+ std::tuple<ParentLayerPoint, ScreenPoint> GetDisplacementsForPanGesture(
+ const PanGestureInput& aEvent);
+
+ private:
+ friend class AutoApplyAsyncTestAttributes;
+
+ bool SuppressAsyncScrollOffset() const;
+
+ /**
+ * Applies |mTestAsyncScrollOffset| and |mTestAsyncZoom| to this
+ * AsyncPanZoomController. Calls |SampleCompositedAsyncTransform| to ensure
+ * that the GetCurrentAsync* functions consider the test offset and zoom in
+ * their computations.
+ */
+ void ApplyAsyncTestAttributes(const RecursiveMutexAutoLock& aProofOfLock);
+
+ /**
+ * Sets this AsyncPanZoomController's FrameMetrics to |aPrevFrameMetrics| and
+ * calls |SampleCompositedAsyncTransform| to unapply any test values applied
+ * by |ApplyAsyncTestAttributes|.
+ */
+ void UnapplyAsyncTestAttributes(const RecursiveMutexAutoLock& aProofOfLock,
+ const FrameMetrics& aPrevFrameMetrics,
+ const ParentLayerPoint& aPrevOverscroll);
+
+ /* ===================================================================
+ * The functions and members in this section are used to manage
+ * the state that tracks what this APZC is doing with the input events.
+ */
+ protected:
+ enum PanZoomState {
+ NOTHING, /* no touch-start events received */
+ FLING, /* all touches removed, but we're still scrolling page */
+ TOUCHING, /* one touch-start event received */
+
+ PANNING, /* panning the frame */
+ PANNING_LOCKED_X, /* touch-start followed by move (i.e. panning with axis
+ lock) X axis */
+ PANNING_LOCKED_Y, /* as above for Y axis */
+
+ PAN_MOMENTUM, /* like PANNING, but controlled by momentum PanGestureInput
+ events */
+
+ PINCHING, /* nth touch-start, where n > 1. this mode allows pan and zoom */
+ ANIMATING_ZOOM, /* animated zoom to a new rect */
+ OVERSCROLL_ANIMATION, /* Spring-based animation used to relieve overscroll
+ once the finger is lifted. */
+ SMOOTH_SCROLL, /* Smooth scrolling to destination, with physics
+ controlled by prefs specific to the scroll origin. */
+ SMOOTHMSD_SCROLL, /* SmoothMSD scrolling to destination. Used by
+ CSSOM-View smooth scroll-behavior */
+ WHEEL_SCROLL, /* Smooth scrolling to a destination for a wheel event. */
+ KEYBOARD_SCROLL, /* Smooth scrolling to a destination for a keyboard event.
+ */
+ AUTOSCROLL, /* Autoscroll animation. */
+ SCROLLBAR_DRAG /* Async scrollbar drag. */
+ };
+ // This is in theory protected by |mRecursiveMutex|; that is, it should be
+ // held whenever this is updated. In practice though... see bug 897017.
+ PanZoomState mState;
+
+ AxisX mX;
+ AxisY mY;
+
+ /**
+ * Returns wheter the given input state is a user pan-gesture.
+ *
+ * Note: momentum pan gesture states are not considered a panning state.
+ */
+ static bool IsPanningState(PanZoomState aState);
+
+ /**
+ * Returns wheter a delayed transform end is queued.
+ */
+ bool IsDelayedTransformEndSet();
+
+ /**
+ * Returns wheter a delayed transform end is queued.
+ */
+ void SetDelayedTransformEnd(bool aDelayedTransformEnd);
+
+ /**
+ * Returns whether the specified PanZoomState does not need to be reset when
+ * a scroll offset update is processed.
+ */
+ static bool CanHandleScrollOffsetUpdate(PanZoomState aState);
+
+ /**
+ * Determine whether a main-thread scroll offset update should result in
+ * a call to CancelAnimation() (which interrupts in-progress animations and
+ * gestures).
+ *
+ * If the update is a relative update, |aRelativeDelta| contains its amount.
+ * If the update is not a relative update, GetMetrics() should already reflect
+ * the new offset at the time of the call.
+ */
+ bool ShouldCancelAnimationForScrollUpdate(
+ const Maybe<CSSPoint>& aRelativeDelta);
+
+ private:
+ friend class StateChangeNotificationBlocker;
+ /**
+ * A counter of how many StateChangeNotificationBlockers are active.
+ * A non-zero count will prevent state change notifications from
+ * being dispatched. Only code that holds mRecursiveMutex should touch this.
+ */
+ int mNotificationBlockers;
+
+ /**
+ * Helper to set the current state, without content controller events
+ * for the state change. This is useful in cases where the content
+ * controller events may need to be delayed.
+ */
+ PanZoomState SetStateNoContentControllerDispatch(PanZoomState aNewState);
+
+ /**
+ * Helper to set the current state. Holds mRecursiveMutex before actually
+ * setting it and fires content controller events based on state changes.
+ * Always set the state using this call, do not set it directly.
+ */
+ void SetState(PanZoomState aNewState);
+ /**
+ * Helper for getting the current state which acquires mRecursiveMutex
+ * before accessing the field.
+ */
+ PanZoomState GetState() const;
+ /**
+ * Fire content controller notifications about state changes, assuming no
+ * StateChangeNotificationBlocker has been activated.
+ */
+ void DispatchStateChangeNotification(PanZoomState aOldState,
+ PanZoomState aNewState);
+ /**
+ * Internal helpers for checking general state of this apzc.
+ */
+ bool IsInTransformingState() const;
+ static bool IsTransformingState(PanZoomState aState);
+
+ /* ===================================================================
+ * The functions and members in this section are used to manage
+ * blocks of touch events and the state needed to deal with content
+ * listeners.
+ */
+ public:
+ /**
+ * Flush a repaint request if one is needed, without throttling it with the
+ * paint throttler.
+ */
+ void FlushRepaintForNewInputBlock();
+
+ /**
+ * Given an input event and the touch block it belongs to, check if the
+ * event can lead to a panning/zooming behavior.
+ * This is used for logic related to the pointer events spec (figuring out
+ * when to dispatch the pointercancel event), as well as an input to the
+ * computation of the APZHandledResult for the event (used on Android to
+ * govern dynamic toolbar and pull-to-refresh behaviour).
+ */
+ PointerEventsConsumableFlags ArePointerEventsConsumable(
+ TouchBlockState* aBlock, const MultiTouchInput& aInput);
+
+ /**
+ * Clear internal state relating to touch input handling.
+ */
+ void ResetTouchInputState();
+
+ /**
+ Clear internal state relating to pan gesture input handling.
+ */
+ void ResetPanGestureInputState();
+
+ /**
+ * Gets a ref to the input queue that is shared across the entire tree
+ * manager.
+ */
+ const RefPtr<InputQueue>& GetInputQueue() const;
+
+ private:
+ void CancelAnimationAndGestureState();
+
+ RefPtr<InputQueue> mInputQueue;
+ InputBlockState* GetCurrentInputBlock() const;
+ TouchBlockState* GetCurrentTouchBlock() const;
+ bool HasReadyTouchBlock() const;
+
+ PanGestureBlockState* GetCurrentPanGestureBlock() const;
+ PinchGestureBlockState* GetCurrentPinchGestureBlock() const;
+
+ private:
+ /* ===================================================================
+ * The functions and members in this section are used to manage
+ * fling animations, smooth scroll animations, and overscroll
+ * during a fling or smooth scroll.
+ */
+ public:
+ /**
+ * Attempt a fling with the velocity specified in |aHandoffState|.
+ * |aHandoffState.mIsHandoff| should be true iff. the fling was handed off
+ * from a previous APZC, and determines whether acceleration is applied
+ * to the fling.
+ * We only accept the fling in the direction(s) in which we are pannable.
+ * Returns the "residual velocity", i.e. the portion of
+ * |aHandoffState.mVelocity| that this APZC did not consume.
+ */
+ ParentLayerPoint AttemptFling(const FlingHandoffState& aHandoffState);
+
+ ParentLayerPoint AdjustHandoffVelocityForOverscrollBehavior(
+ ParentLayerPoint& aHandoffVelocity) const;
+
+ private:
+ friend class StackScrollerFlingAnimation;
+ friend class AutoscrollAnimation;
+ template <typename FlingPhysics>
+ friend class GenericFlingAnimation;
+ friend class AndroidFlingPhysics;
+ friend class DesktopFlingPhysics;
+ friend class OverscrollAnimation;
+ friend class SmoothMsdScrollAnimation;
+ friend class GenericScrollAnimation;
+ friend class WheelScrollAnimation;
+ friend class ZoomAnimation;
+
+ friend class GenericOverscrollEffect;
+ friend class WidgetOverscrollEffect;
+ friend struct apz::AsyncScrollThumbTransformer;
+
+ FlingAccelerator mFlingAccelerator;
+
+ // Indicates if the repaint-during-pinch timer is currently set
+ bool mPinchPaintTimerSet;
+
+ // Indicates a delayed transform end notification is queued, and the
+ // transform-end timer is currently set. mRecursiveMutex must be held
+ // when using or modifying this member.
+ bool mDelayedTransformEnd;
+
+ // Deal with overscroll resulting from a fling animation. This is only ever
+ // called on APZC instances that were actually performing a fling.
+ // The overscroll is handled by trying to hand the fling off to an APZC
+ // later in the handoff chain, or if there are no takers, continuing the
+ // fling and entering an overscrolled state.
+ void HandleFlingOverscroll(
+ const ParentLayerPoint& aVelocity, SideBits aOverscrollSideBits,
+ const RefPtr<const OverscrollHandoffChain>& aOverscrollHandoffChain,
+ const RefPtr<const AsyncPanZoomController>& aScrolledApzc);
+
+ void HandleSmoothScrollOverscroll(const ParentLayerPoint& aVelocity,
+ SideBits aOverscrollSideBits);
+
+ // Start an overscroll animation with the given initial velocity.
+ void StartOverscrollAnimation(const ParentLayerPoint& aVelocity,
+ SideBits aOverscrollSideBits);
+
+ // Start a smooth-scrolling animation to the given destination, with physics
+ // based on the prefs for the indicated origin.
+ void SmoothScrollTo(const CSSPoint& aDestination,
+ const ScrollOrigin& aOrigin);
+
+ // Start a smooth-scrolling animation to the given destination, with MSD
+ // physics that is suited for scroll-snapping.
+ void SmoothMsdScrollTo(CSSSnapTarget&& aDestination,
+ ScrollTriggeredByScript aTriggeredByScript);
+
+ // Returns whether overscroll is allowed during an event.
+ bool AllowScrollHandoffInCurrentBlock() const;
+
+ // Invoked by the pinch repaint timer.
+ void DoDelayedRequestContentRepaint();
+
+ // Invoked by the on pan-end handler to ensure that scrollend is only
+ // fired once when a momentum pan or scroll snap is triggered as a
+ // result of the pan gesture.
+ void DoDelayedTransformEndNotification(PanZoomState aOldState);
+
+ // Compute the number of ParentLayer pixels per (Screen) inch at the given
+ // point and in the given direction.
+ float ComputePLPPI(ParentLayerPoint aPoint,
+ ParentLayerPoint aDirection) const;
+
+ Maybe<CSSPoint> GetCurrentAnimationDestination(
+ const RecursiveMutexAutoLock& aProofOfLock) const;
+
+ /* ===================================================================
+ * The functions and members in this section are used to make ancestor chains
+ * out of APZC instances. These chains can only be walked or manipulated
+ * while holding the lock in the associated APZCTreeManager instance.
+ */
+ public:
+ void SetParent(AsyncPanZoomController* aParent) { mParent = aParent; }
+
+ AsyncPanZoomController* GetParent() const { return mParent; }
+
+ /* Returns true if there is no APZC higher in the tree with the same
+ * layers id.
+ */
+ bool HasNoParentWithSameLayersId() const {
+ return !mParent || (mParent->mLayersId != mLayersId);
+ }
+
+ bool IsRootForLayersId() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mScrollMetadata.IsLayersIdRoot();
+ }
+
+ bool IsRootContent() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return Metrics().IsRootContent();
+ }
+
+ private:
+ // |mTreeManager| belongs in this section but it's declaration is a bit
+ // further above due to initialization-order constraints.
+
+ RefPtr<AsyncPanZoomController> mParent;
+
+ /* ===================================================================
+ * The functions and members in this section are used for scrolling,
+ * including handing off scroll to another APZC, and overscrolling.
+ */
+
+ ScrollableLayerGuid::ViewID GetScrollId() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return Metrics().GetScrollId();
+ }
+
+ public:
+ ScrollableLayerGuid::ViewID GetScrollHandoffParentId() const {
+ return mScrollMetadata.GetScrollParentId();
+ }
+
+ /**
+ * Attempt to scroll in response to a touch-move from |aStartPoint| to
+ * |aEndPoint|, which are in our (transformed) screen coordinates.
+ * Due to overscroll handling, there may not actually have been a touch-move
+ * at these points, but this function will scroll as if there had been.
+ * If this attempt causes overscroll (i.e. the layer cannot be scrolled
+ * by the entire amount requested), the overscroll is passed back to the
+ * tree manager via APZCTreeManager::DispatchScroll(). If the tree manager
+ * does not find an APZC further in the handoff chain to accept the
+ * overscroll, and this APZC is pannable, this APZC enters an overscrolled
+ * state.
+ * |aOverscrollHandoffChain| and |aOverscrollHandoffChainIndex| are used by
+ * the tree manager to keep track of which APZC to hand off the overscroll
+ * to; this function increments the chain and the index and passes it on to
+ * APZCTreeManager::DispatchScroll() in the event of overscroll.
+ * Returns true iff. this APZC, or an APZC further down the
+ * handoff chain, accepted the scroll (possibly entering an overscrolled
+ * state). If this returns false, the caller APZC knows that it should enter
+ * an overscrolled state itself if it can.
+ * aStartPoint and aEndPoint are modified depending on how much of the
+ * scroll gesture was consumed by APZCs in the handoff chain.
+ */
+ bool AttemptScroll(ParentLayerPoint& aStartPoint, ParentLayerPoint& aEndPoint,
+ OverscrollHandoffState& aOverscrollHandoffState);
+
+ void FlushRepaintForOverscrollHandoff();
+
+ /**
+ * If overscrolled, start a snap-back animation and return true. Even if not
+ * overscrolled, this function tries to snap back to if there's an applicable
+ * scroll snap point.
+ * Otherwise return false.
+ */
+ bool SnapBackIfOverscrolled();
+
+ /**
+ * NOTE: Similar to above but this function doesn't snap back to the scroll
+ * snap point.
+ */
+ bool SnapBackIfOverscrolledForMomentum(const ParentLayerPoint& aVelocity);
+
+ /**
+ * Build the chain of APZCs along which scroll will be handed off when
+ * this APZC receives input events.
+ *
+ * Notes on lifetime and const-correctness:
+ * - The returned handoff chain is |const|, to indicate that it cannot be
+ * changed after being built.
+ * - When passing the chain to a function that uses it without storing it,
+ * pass it by reference-to-const (as in |const OverscrollHandoffChain&|).
+ * - When storing the chain, store it by RefPtr-to-const (as in
+ * |RefPtr<const OverscrollHandoffChain>|). This ensures the chain is
+ * kept alive. Note that queueing a task that uses the chain as an
+ * argument constitutes storing, as the task may outlive its queuer.
+ * - When passing the chain to a function that will store it, pass it as
+ * |const RefPtr<const OverscrollHandoffChain>&|. This allows the
+ * function to copy it into the |RefPtr<const OverscrollHandoffChain>|
+ * that will store it, while avoiding an unnecessary copy (and thus
+ * AddRef() and Release()) when passing it.
+ */
+ RefPtr<const OverscrollHandoffChain> BuildOverscrollHandoffChain();
+
+ private:
+ /**
+ * A helper function for calling APZCTreeManager::DispatchScroll().
+ * Guards against the case where the APZC is being concurrently destroyed
+ * (and thus mTreeManager is being nulled out).
+ */
+ bool CallDispatchScroll(ParentLayerPoint& aStartPoint,
+ ParentLayerPoint& aEndPoint,
+ OverscrollHandoffState& aOverscrollHandoffState);
+
+ void RecordScrollPayload(const TimeStamp& aTimeStamp);
+
+ /**
+ * A helper function for overscrolling during panning. This is a wrapper
+ * around OverscrollBy() that also implements restrictions on entering
+ * overscroll based on the pan angle.
+ */
+ void OverscrollForPanning(ParentLayerPoint& aOverscroll,
+ const ScreenPoint& aPanDistance);
+
+ /**
+ * Try to overscroll by 'aOverscroll'.
+ * If we are pannable on a particular axis, that component of 'aOverscroll'
+ * is transferred to any existing overscroll.
+ */
+ void OverscrollBy(ParentLayerPoint& aOverscroll);
+
+ /* ===================================================================
+ * The functions and members in this section are used to maintain the
+ * area that this APZC instance is responsible for. This is used when
+ * hit-testing to see which APZC instance should handle touch events.
+ */
+ public:
+ void SetAncestorTransform(const AncestorTransform& aAncestorTransform) {
+ mAncestorTransform = aAncestorTransform;
+ }
+
+ Matrix4x4 GetAncestorTransform() const {
+ return mAncestorTransform.CombinedTransform();
+ }
+
+ bool AncestorTransformContainsPerspective() const {
+ return mAncestorTransform.ContainsPerspectiveTransform();
+ }
+
+ // Return the perspective transform component of the ancestor transform.
+ Matrix4x4 GetAncestorTransformPerspective() const {
+ return mAncestorTransform.GetPerspectiveTransform();
+ }
+
+ // Returns whether or not this apzc contains the given screen point within
+ // its composition bounds.
+ bool Contains(const ScreenIntPoint& aPoint) const;
+
+ bool IsInOverscrollGutter(const ScreenPoint& aHitTestPoint) const;
+ bool IsInOverscrollGutter(const ParentLayerPoint& aHitTestPoint) const;
+
+ bool IsOverscrolled() const;
+
+ bool IsOverscrollAnimationRunning() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mState == OVERSCROLL_ANIMATION;
+ }
+
+ // IsPhysicallyOverscrolled() checks whether the APZC is overscrolled
+ // by an overscroll effect which applies a transform to the APZC's contents.
+ bool IsPhysicallyOverscrolled() const;
+
+ private:
+ bool IsInInvalidOverscroll() const;
+
+ public:
+ bool IsInPanningState() const;
+
+ // Returns whether being in the middle of a gesture. E.g., this APZC has
+ // started handling a pan gesture but hasn't yet received pan-end, etc.
+ bool IsInScrollingGesture() const;
+
+ private:
+ /* This is the cumulative CSS transform for all the layers from (and
+ * including) the parent APZC down to (but excluding) this one, and excluding
+ * any perspective transforms. */
+ AncestorTransform mAncestorTransform;
+
+ /* ===================================================================
+ * The functions and members in this section are used for testing
+ * and assertion purposes only.
+ */
+ public:
+ /**
+ * Gets whether this APZC has performed async key scrolling.
+ */
+ bool TestHasAsyncKeyScrolled() const { return mTestHasAsyncKeyScrolled; }
+
+ /**
+ * Set an extra offset for testing async scrolling.
+ */
+ void SetTestAsyncScrollOffset(const CSSPoint& aPoint);
+ /**
+ * Set an extra offset for testing async scrolling.
+ */
+ void SetTestAsyncZoom(const LayerToParentLayerScale& aZoom);
+
+ LayersId GetLayersId() const { return mLayersId; }
+
+ bool IsAsyncZooming() const {
+ RecursiveMutexAutoLock lock(mRecursiveMutex);
+ return mState == PINCHING || mState == ANIMATING_ZOOM;
+ }
+
+ private:
+ // The timestamp of the latest touch start event.
+ TimeStamp mTouchStartTime;
+ // Used for interpolating touch events that cross the touch-start
+ // tolerance threshold.
+ struct TouchSample {
+ ExternalPoint mPosition;
+ TimeStamp mTimeStamp;
+ };
+ // Information about the latest touch event.
+ // This is only populated when we're in the TOUCHING state
+ // (and thus the last touch event has only one touch point).
+ TouchSample mLastTouch;
+ // The time duration between mTouchStartTime and the touchmove event that
+ // started the pan (the touchmove event that transitioned this APZC from the
+ // TOUCHING state to one of the PANNING* states). Only valid while this APZC
+ // is in a panning state.
+ TimeDuration mTouchStartRestingTimeBeforePan;
+ Maybe<ParentLayerCoord> mMinimumVelocityDuringPan;
+ // This variable needs to be protected by |mRecursiveMutex|.
+ ScrollSnapTargetIds mLastSnapTargetIds;
+ // Extra offset to add to the async scroll position for testing
+ CSSPoint mTestAsyncScrollOffset;
+ // Extra zoom to include in the aync zoom for testing
+ LayerToParentLayerScale mTestAsyncZoom;
+ uint8_t mTestAttributeAppliers;
+ // Flag to track whether or not this APZC has ever async key scrolled.
+ bool mTestHasAsyncKeyScrolled;
+
+ /* ===================================================================
+ * The functions and members in this section are used for checkerboard
+ * recording.
+ */
+ private:
+ // Helper function to update the in-progress checkerboard event, if any.
+ void UpdateCheckerboardEvent(const MutexAutoLock& aProofOfLock,
+ uint32_t aMagnitude);
+
+ // Mutex protecting mCheckerboardEvent
+ Mutex mCheckerboardEventLock MOZ_UNANNOTATED;
+ // This is created when this APZC instance is first included as part of a
+ // composite. If a checkerboard event takes place, this is destroyed at the
+ // end of the event, and a new one is created on the next composite.
+ UniquePtr<CheckerboardEvent> mCheckerboardEvent;
+ // This is used to track the total amount of time that we could reasonably
+ // be checkerboarding. Combined with other info, this allows us to
+ // meaningfully say how frequently users actually encounter checkerboarding.
+ PotentialCheckerboardDurationTracker mPotentialCheckerboardTracker;
+
+ /* ===================================================================
+ * The functions in this section are used for CSS scroll snapping.
+ */
+
+ // If moving |aStartPosition| by |aDelta| should trigger scroll snapping,
+ // adjust |aDelta| to reflect the snapping (that is, make it a delta that will
+ // take us to the desired snap point). The delta is interpreted as being
+ // relative to |aStartPosition|, and if a target snap point is found,
+ // |aStartPosition| is also updated, to the value of the snap point.
+ // |aUnit| affects the snapping behaviour (see ScrollSnapUtils::
+ // GetSnapPointForDestination).
+ // Returns true iff. a target snap point was found.
+ Maybe<CSSSnapTarget> MaybeAdjustDeltaForScrollSnapping(
+ ScrollUnit aUnit, ScrollSnapFlags aSnapFlags, ParentLayerPoint& aDelta,
+ CSSPoint& aStartPosition);
+
+ // A wrapper function of MaybeAdjustDeltaForScrollSnapping for
+ // ScrollWheelInput.
+ Maybe<CSSSnapTarget> MaybeAdjustDeltaForScrollSnappingOnWheelInput(
+ const ScrollWheelInput& aEvent, ParentLayerPoint& aDelta,
+ CSSPoint& aStartPosition);
+
+ Maybe<CSSSnapTarget> MaybeAdjustDestinationForScrollSnapping(
+ const KeyboardInput& aEvent, CSSPoint& aDestination,
+ ScrollSnapFlags aSnapFlags);
+
+ // Snap to a snap position nearby the current scroll position, if appropriate.
+ void ScrollSnap(ScrollSnapFlags aSnapFlags);
+
+ // Snap to a snap position nearby the destination predicted based on the
+ // current velocity, if appropriate.
+ void ScrollSnapToDestination();
+
+ // Snap to a snap position nearby the provided destination, if appropriate.
+ void ScrollSnapNear(const CSSPoint& aDestination, ScrollSnapFlags aSnapFlags);
+
+ // Find a snap point near |aDestination| that we should snap to.
+ // Returns the snap point if one was found, or an empty Maybe otherwise.
+ // |aUnit| affects the snapping behaviour (see ScrollSnapUtils::
+ // GetSnapPointForDestination). It should generally be determined by the
+ // type of event that's triggering the scroll.
+ Maybe<CSSSnapTarget> FindSnapPointNear(const CSSPoint& aDestination,
+ ScrollUnit aUnit,
+ ScrollSnapFlags aSnapFlags);
+
+ // If |aOriginalEvent| crosses the touch-start tolerance threshold, split it
+ // into two events: one that just reaches the threshold, and the remainder.
+ //
+ // |aPanThreshold| is the touch-start tolerance, and |aVectorLength| is
+ // the length of the vector from the touch-start position to |aOriginalEvent|.
+ // These values could be computed from |aOriginalEvent| but they are
+ // passed in for convenience since the caller also needs to compute them.
+ //
+ // |aExtPoint| is the position of |aOriginalEvent| in External coordinates,
+ // and in case of a split is modified by the function to reflect the position
+ // of of the first event. This is a workaround for the fact that recomputing
+ // the External position from the returned event would require a round-trip
+ // through |mScreenPoint| which is an integer.
+ Maybe<std::pair<MultiTouchInput, MultiTouchInput>> MaybeSplitTouchMoveEvent(
+ const MultiTouchInput& aOriginalEvent, ScreenCoord aPanThreshold,
+ float aVectorLength, ExternalPoint& aExtPoint);
+
+ friend std::ostream& operator<<(
+ std::ostream& aOut, const AsyncPanZoomController::PanZoomState& aState);
+};
+
+} // namespace layers
+} // namespace mozilla
+
+#endif // mozilla_layers_PanZoomController_h