1 files changed, 837 insertions, 0 deletions
diff --git a/gfx/layers/apz/src/InputBlockState.cpp b/gfx/layers/apz/src/InputBlockState.cpp
new file mode 100644
index 0000000000..20f29d7d99
--- /dev/null
+++ b/gfx/layers/apz/src/InputBlockState.cpp
@@ -0,0 +1,837 @@
+/* -*- 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/. */
+
+#include "InputBlockState.h"
+
+#include "APZUtils.h"
+#include "AsyncPanZoomController.h"  // for AsyncPanZoomController
+#include "ScrollAnimationPhysics.h"  // for kScrollSeriesTimeoutMs
+
+#include "mozilla/MouseEvents.h"
+#include "mozilla/StaticPrefs_apz.h"
+#include "mozilla/StaticPrefs_layout.h"
+#include "mozilla/StaticPrefs_mousewheel.h"
+#include "mozilla/StaticPrefs_test.h"
+#include "mozilla/Telemetry.h"  // for Telemetry
+#include "mozilla/ToString.h"
+#include "mozilla/layers/IAPZCTreeManager.h"  // for AllowedTouchBehavior
+#include "OverscrollHandoffState.h"
+#include "QueuedInput.h"
+
+static mozilla::LazyLogModule sApzIbsLog("apz.inputstate");
+#define TBS_LOG(...) MOZ_LOG(sApzIbsLog, LogLevel::Debug, (__VA_ARGS__))
+
+namespace mozilla {
+namespace layers {
+
+static uint64_t sBlockCounter = InputBlockState::NO_BLOCK_ID + 1;
+
+InputBlockState::InputBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags)
+    : mTargetApzc(aTargetApzc),
+      mRequiresTargetConfirmation(aFlags.mRequiresTargetConfirmation),
+      mBlockId(sBlockCounter++),
+      mTransformToApzc(aTargetApzc->GetTransformToThis()) {
+  // We should never be constructed with a nullptr target.
+  MOZ_ASSERT(mTargetApzc);
+  mOverscrollHandoffChain = mTargetApzc->BuildOverscrollHandoffChain();
+  // If a new block starts on a scrollthumb and we have APZ scrollbar
+  // dragging enabled, defer confirmation until we get the drag metrics
+  // for the thumb.
+  bool startingDrag = StaticPrefs::apz_drag_enabled() && aFlags.mHitScrollThumb;
+  mTargetConfirmed = aFlags.mTargetConfirmed && !startingDrag
+                         ? TargetConfirmationState::eConfirmed
+                         : TargetConfirmationState::eUnconfirmed;
+}
+
+bool InputBlockState::SetConfirmedTargetApzc(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationState aState, InputData* aFirstInput,
+    bool aForScrollbarDrag) {
+  MOZ_ASSERT(aState == TargetConfirmationState::eConfirmed ||
+             aState == TargetConfirmationState::eTimedOut);
+
+  if (mTargetConfirmed == TargetConfirmationState::eTimedOut &&
+      aState == TargetConfirmationState::eConfirmed) {
+    // The main thread finally responded. We had already timed out the
+    // confirmation, but we want to update the state internally so that we
+    // can record the time for telemetry purposes.
+    mTargetConfirmed = TargetConfirmationState::eTimedOutAndMainThreadResponded;
+  }
+  // Sometimes, bugs in compositor hit testing can lead to APZ confirming
+  // a different target than the main thread. If this happens for a drag
+  // block created for a scrollbar drag, the consequences can be fairly
+  // user-unfriendly, such as the scrollbar not being draggable at all,
+  // or it scrolling the contents of the wrong scrollframe. In debug
+  // builds, we assert in this situation, so that the
+  // underlying compositor hit testing bug can be fixed. In release builds,
+  // however, we just silently accept the main thread's confirmed target,
+  // which will produce the expected behaviour (apart from drag events
+  // received so far being dropped).
+  if (AsDragBlock() && aForScrollbarDrag &&
+      mTargetConfirmed == TargetConfirmationState::eConfirmed &&
+      aState == TargetConfirmationState::eConfirmed && mTargetApzc &&
+      aTargetApzc && mTargetApzc->GetGuid() != aTargetApzc->GetGuid()) {
+    MOZ_ASSERT(false,
+               "APZ and main thread confirmed scrollbar drag block with "
+               "different targets");
+    UpdateTargetApzc(aTargetApzc);
+    return true;
+  }
+
+  if (mTargetConfirmed != TargetConfirmationState::eUnconfirmed) {
+    return false;
+  }
+  mTargetConfirmed = aState;
+
+  TBS_LOG("%p got confirmed target APZC %p\n", this, mTargetApzc.get());
+  if (mTargetApzc == aTargetApzc) {
+    // The confirmed target is the same as the tentative one, so we're done.
+    return true;
+  }
+
+  TBS_LOG("%p replacing unconfirmed target %p with real target %p\n", this,
+          mTargetApzc.get(), aTargetApzc.get());
+
+  UpdateTargetApzc(aTargetApzc);
+  return true;
+}
+
+void InputBlockState::UpdateTargetApzc(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc) {
+  // note that aTargetApzc MAY be null here.
+  mTargetApzc = aTargetApzc;
+  mTransformToApzc = aTargetApzc ? aTargetApzc->GetTransformToThis()
+                                 : ScreenToParentLayerMatrix4x4();
+  mOverscrollHandoffChain =
+      (mTargetApzc ? mTargetApzc->BuildOverscrollHandoffChain() : nullptr);
+}
+
+const RefPtr<AsyncPanZoomController>& InputBlockState::GetTargetApzc() const {
+  return mTargetApzc;
+}
+
+const RefPtr<const OverscrollHandoffChain>&
+InputBlockState::GetOverscrollHandoffChain() const {
+  return mOverscrollHandoffChain;
+}
+
+uint64_t InputBlockState::GetBlockId() const { return mBlockId; }
+
+bool InputBlockState::IsTargetConfirmed() const {
+  return mTargetConfirmed != TargetConfirmationState::eUnconfirmed;
+}
+
+bool InputBlockState::HasReceivedRealConfirmedTarget() const {
+  return mTargetConfirmed == TargetConfirmationState::eConfirmed ||
+         mTargetConfirmed ==
+             TargetConfirmationState::eTimedOutAndMainThreadResponded;
+}
+
+bool InputBlockState::ShouldDropEvents() const {
+  return mRequiresTargetConfirmation &&
+         (mTargetConfirmed != TargetConfirmationState::eConfirmed);
+}
+
+bool InputBlockState::IsDownchainOf(AsyncPanZoomController* aA,
+                                    AsyncPanZoomController* aB) const {
+  if (aA == aB) {
+    return true;
+  }
+
+  bool seenA = false;
+  for (size_t i = 0; i < mOverscrollHandoffChain->Length(); ++i) {
+    AsyncPanZoomController* apzc = mOverscrollHandoffChain->GetApzcAtIndex(i);
+    if (apzc == aB) {
+      return seenA;
+    }
+    if (apzc == aA) {
+      seenA = true;
+    }
+  }
+  return false;
+}
+
+void InputBlockState::SetScrolledApzc(AsyncPanZoomController* aApzc) {
+  // An input block should only have one scrolled APZC.
+  MOZ_ASSERT(!mScrolledApzc || (StaticPrefs::apz_allow_immediate_handoff()
+                                    ? IsDownchainOf(mScrolledApzc, aApzc)
+                                    : mScrolledApzc == aApzc));
+
+  mScrolledApzc = aApzc;
+}
+
+AsyncPanZoomController* InputBlockState::GetScrolledApzc() const {
+  return mScrolledApzc;
+}
+
+bool InputBlockState::IsDownchainOfScrolledApzc(
+    AsyncPanZoomController* aApzc) const {
+  MOZ_ASSERT(aApzc && mScrolledApzc);
+
+  return IsDownchainOf(mScrolledApzc, aApzc);
+}
+
+void InputBlockState::DispatchEvent(const InputData& aEvent) const {
+  GetTargetApzc()->HandleInputEvent(aEvent, mTransformToApzc);
+}
+
+CancelableBlockState::CancelableBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags)
+    : InputBlockState(aTargetApzc, aFlags),
+      mPreventDefault(false),
+      mContentResponded(false),
+      mContentResponseTimerExpired(false) {}
+
+bool CancelableBlockState::SetContentResponse(bool aPreventDefault) {
+  if (mContentResponded) {
+    return false;
+  }
+  TBS_LOG("%p got content response %d with timer expired %d\n", this,
+          aPreventDefault, mContentResponseTimerExpired);
+  mPreventDefault = aPreventDefault;
+  mContentResponded = true;
+  return true;
+}
+
+bool CancelableBlockState::TimeoutContentResponse() {
+  if (mContentResponseTimerExpired) {
+    return false;
+  }
+  TBS_LOG("%p got content timer expired with response received %d\n", this,
+          mContentResponded);
+  if (!mContentResponded) {
+    mPreventDefault = false;
+  }
+  mContentResponseTimerExpired = true;
+  return true;
+}
+
+bool CancelableBlockState::IsContentResponseTimerExpired() const {
+  return mContentResponseTimerExpired;
+}
+
+bool CancelableBlockState::IsDefaultPrevented() const {
+  MOZ_ASSERT(mContentResponded || mContentResponseTimerExpired);
+  return mPreventDefault;
+}
+
+bool CancelableBlockState::HasReceivedAllContentNotifications() const {
+  return HasReceivedRealConfirmedTarget() && mContentResponded;
+}
+
+bool CancelableBlockState::IsReadyForHandling() const {
+  if (!IsTargetConfirmed()) {
+    return false;
+  }
+  return mContentResponded || mContentResponseTimerExpired;
+}
+
+bool CancelableBlockState::ShouldDropEvents() const {
+  return InputBlockState::ShouldDropEvents() || IsDefaultPrevented();
+}
+
+DragBlockState::DragBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags, const MouseInput& aInitialEvent)
+    : CancelableBlockState(aTargetApzc, aFlags), mReceivedMouseUp(false) {}
+
+bool DragBlockState::HasReceivedMouseUp() { return mReceivedMouseUp; }
+
+void DragBlockState::MarkMouseUpReceived() { mReceivedMouseUp = true; }
+
+void DragBlockState::SetInitialThumbPos(CSSCoord aThumbPos) {
+  mInitialThumbPos = aThumbPos;
+}
+
+void DragBlockState::SetDragMetrics(const AsyncDragMetrics& aDragMetrics) {
+  mDragMetrics = aDragMetrics;
+}
+
+void DragBlockState::DispatchEvent(const InputData& aEvent) const {
+  MouseInput mouseInput = aEvent.AsMouseInput();
+  if (!mouseInput.TransformToLocal(mTransformToApzc)) {
+    return;
+  }
+
+  GetTargetApzc()->HandleDragEvent(mouseInput, mDragMetrics, mInitialThumbPos);
+}
+
+bool DragBlockState::MustStayActive() { return !mReceivedMouseUp; }
+
+const char* DragBlockState::Type() { return "drag"; }
+// This is used to track the current wheel transaction.
+static uint64_t sLastWheelBlockId = InputBlockState::NO_BLOCK_ID;
+
+WheelBlockState::WheelBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags, const ScrollWheelInput& aInitialEvent)
+    : CancelableBlockState(aTargetApzc, aFlags),
+      mScrollSeriesCounter(0),
+      mTransactionEnded(false) {
+  sLastWheelBlockId = GetBlockId();
+
+  if (aFlags.mTargetConfirmed) {
+    // Find the nearest APZC in the overscroll handoff chain that is scrollable.
+    // If we get a content confirmation later that the apzc is different, then
+    // content should have found a scrollable apzc, so we don't need to handle
+    // that case.
+    RefPtr<AsyncPanZoomController> apzc =
+        mOverscrollHandoffChain->FindFirstScrollable(aInitialEvent,
+                                                     &mAllowedScrollDirections);
+
+    // If nothing is scrollable, we don't consider this block as starting a
+    // transaction.
+    if (!apzc) {
+      EndTransaction();
+      return;
+    }
+
+    if (apzc != GetTargetApzc()) {
+      UpdateTargetApzc(apzc);
+    }
+  }
+}
+
+bool WheelBlockState::SetContentResponse(bool aPreventDefault) {
+  if (aPreventDefault) {
+    EndTransaction();
+  }
+  return CancelableBlockState::SetContentResponse(aPreventDefault);
+}
+
+bool WheelBlockState::SetConfirmedTargetApzc(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationState aState, InputData* aFirstInput,
+    bool aForScrollbarDrag) {
+  // The APZC that we find via APZCCallbackHelpers may not be the same APZC
+  // ESM or OverscrollHandoff would have computed. Make sure we get the right
+  // one by looking for the first apzc the next pending event can scroll.
+  RefPtr<AsyncPanZoomController> apzc = aTargetApzc;
+  if (apzc && aFirstInput) {
+    apzc = apzc->BuildOverscrollHandoffChain()->FindFirstScrollable(
+        *aFirstInput, &mAllowedScrollDirections);
+  }
+
+  InputBlockState::SetConfirmedTargetApzc(apzc, aState, aFirstInput,
+                                          aForScrollbarDrag);
+  return true;
+}
+
+void WheelBlockState::Update(ScrollWheelInput& aEvent) {
+  // We might not be in a transaction if the block never started in a
+  // transaction - for example, if nothing was scrollable.
+  if (!InTransaction()) {
+    return;
+  }
+
+  // The current "scroll series" is a like a sub-transaction. It has a separate
+  // timeout of 80ms. Since we need to compute wheel deltas at different phases
+  // of a transaction (for example, when it is updated, and later when the
+  // event action is taken), we affix the scroll series counter to the event.
+  // This makes GetScrollWheelDelta() consistent.
+  if (!mLastEventTime.IsNull() &&
+      (aEvent.mTimeStamp - mLastEventTime).ToMilliseconds() >
+          kScrollSeriesTimeoutMs) {
+    mScrollSeriesCounter = 0;
+  }
+  aEvent.mScrollSeriesNumber = ++mScrollSeriesCounter;
+
+  // If we can't scroll in the direction of the wheel event, we don't update
+  // the last move time. This allows us to timeout a transaction even if the
+  // mouse isn't moving.
+  //
+  // We skip this check if the target is not yet confirmed, so that when it is
+  // confirmed, we don't timeout the transaction.
+  RefPtr<AsyncPanZoomController> apzc = GetTargetApzc();
+  if (IsTargetConfirmed() && !apzc->CanScroll(aEvent)) {
+    return;
+  }
+
+  // Update the time of the last known good event, and reset the mouse move
+  // time to null. This will reset the delays on both the general transaction
+  // timeout and the mouse-move-in-frame timeout.
+  mLastEventTime = aEvent.mTimeStamp;
+  mLastMouseMove = TimeStamp();
+}
+
+bool WheelBlockState::MustStayActive() { return !mTransactionEnded; }
+
+const char* WheelBlockState::Type() { return "scroll wheel"; }
+
+bool WheelBlockState::ShouldAcceptNewEvent() const {
+  if (!InTransaction()) {
+    // If we're not in a transaction, start a new one.
+    return false;
+  }
+
+  RefPtr<AsyncPanZoomController> apzc = GetTargetApzc();
+  if (apzc->IsDestroyed()) {
+    return false;
+  }
+
+  return true;
+}
+
+bool WheelBlockState::MaybeTimeout(const ScrollWheelInput& aEvent) {
+  MOZ_ASSERT(InTransaction());
+
+  if (MaybeTimeout(aEvent.mTimeStamp)) {
+    return true;
+  }
+
+  if (!mLastMouseMove.IsNull()) {
+    // If there's a recent mouse movement, we can time out the transaction
+    // early.
+    TimeDuration duration = TimeStamp::Now() - mLastMouseMove;
+    if (duration.ToMilliseconds() >=
+        StaticPrefs::mousewheel_transaction_ignoremovedelay()) {
+      TBS_LOG("%p wheel transaction timed out after mouse move\n", this);
+      EndTransaction();
+      return true;
+    }
+  }
+
+  return false;
+}
+
+bool WheelBlockState::MaybeTimeout(const TimeStamp& aTimeStamp) {
+  MOZ_ASSERT(InTransaction());
+
+  // End the transaction if the event occurred > 1.5s after the most recently
+  // seen wheel event.
+  TimeDuration duration = aTimeStamp - mLastEventTime;
+  if (duration.ToMilliseconds() <
+      StaticPrefs::mousewheel_transaction_timeout()) {
+    return false;
+  }
+
+  TBS_LOG("%p wheel transaction timed out\n", this);
+
+  if (StaticPrefs::test_mousescroll()) {
+    RefPtr<AsyncPanZoomController> apzc = GetTargetApzc();
+    apzc->NotifyMozMouseScrollEvent(u"MozMouseScrollTransactionTimeout"_ns);
+  }
+
+  EndTransaction();
+  return true;
+}
+
+void WheelBlockState::OnMouseMove(const ScreenIntPoint& aPoint) {
+  MOZ_ASSERT(InTransaction());
+
+  if (!GetTargetApzc()->Contains(aPoint)) {
+    EndTransaction();
+    return;
+  }
+
+  if (mLastMouseMove.IsNull()) {
+    // If the cursor is moving inside the frame, and it is more than the
+    // ignoremovedelay time since the last scroll operation, we record
+    // this as the most recent mouse movement.
+    TimeStamp now = TimeStamp::Now();
+    TimeDuration duration = now - mLastEventTime;
+    if (duration.ToMilliseconds() >=
+        StaticPrefs::mousewheel_transaction_ignoremovedelay()) {
+      mLastMouseMove = now;
+    }
+  }
+}
+
+void WheelBlockState::UpdateTargetApzc(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc) {
+  InputBlockState::UpdateTargetApzc(aTargetApzc);
+
+  // If we found there was no target apzc, then we end the transaction.
+  if (!GetTargetApzc()) {
+    EndTransaction();
+  }
+}
+
+bool WheelBlockState::InTransaction() const {
+  // We consider a wheel block to be in a transaction if it has a confirmed
+  // target and is the most recent wheel input block to be created.
+  if (GetBlockId() != sLastWheelBlockId) {
+    return false;
+  }
+
+  if (mTransactionEnded) {
+    return false;
+  }
+
+  MOZ_ASSERT(GetTargetApzc());
+  return true;
+}
+
+bool WheelBlockState::AllowScrollHandoff() const {
+  // If we're in a wheel transaction, we do not allow overscroll handoff until
+  // a new event ends the wheel transaction.
+  return !IsTargetConfirmed() || !InTransaction();
+}
+
+void WheelBlockState::EndTransaction() {
+  TBS_LOG("%p ending wheel transaction\n", this);
+  mTransactionEnded = true;
+}
+
+PanGestureBlockState::PanGestureBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags, const PanGestureInput& aInitialEvent)
+    : CancelableBlockState(aTargetApzc, aFlags),
+      mInterrupted(false),
+      mWaitingForContentResponse(false) {
+  if (aFlags.mTargetConfirmed) {
+    // Find the nearest APZC in the overscroll handoff chain that is scrollable.
+    // If we get a content confirmation later that the apzc is different, then
+    // content should have found a scrollable apzc, so we don't need to handle
+    // that case.
+    RefPtr<AsyncPanZoomController> apzc =
+        mOverscrollHandoffChain->FindFirstScrollable(aInitialEvent,
+                                                     &mAllowedScrollDirections);
+
+    if (apzc && apzc != GetTargetApzc()) {
+      UpdateTargetApzc(apzc);
+    }
+  }
+}
+
+bool PanGestureBlockState::SetConfirmedTargetApzc(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationState aState, InputData* aFirstInput,
+    bool aForScrollbarDrag) {
+  // The APZC that we find via APZCCallbackHelpers may not be the same APZC
+  // ESM or OverscrollHandoff would have computed. Make sure we get the right
+  // one by looking for the first apzc the next pending event can scroll.
+  RefPtr<AsyncPanZoomController> apzc = aTargetApzc;
+  if (apzc && aFirstInput) {
+    RefPtr<AsyncPanZoomController> scrollableApzc =
+        apzc->BuildOverscrollHandoffChain()->FindFirstScrollable(
+            *aFirstInput, &mAllowedScrollDirections);
+    if (scrollableApzc) {
+      apzc = scrollableApzc;
+    }
+  }
+
+  InputBlockState::SetConfirmedTargetApzc(apzc, aState, aFirstInput,
+                                          aForScrollbarDrag);
+  return true;
+}
+
+bool PanGestureBlockState::MustStayActive() { return !mInterrupted; }
+
+const char* PanGestureBlockState::Type() { return "pan gesture"; }
+
+bool PanGestureBlockState::SetContentResponse(bool aPreventDefault) {
+  if (aPreventDefault) {
+    TBS_LOG("%p setting interrupted flag\n", this);
+    mInterrupted = true;
+  }
+  bool stateChanged = CancelableBlockState::SetContentResponse(aPreventDefault);
+  if (mWaitingForContentResponse) {
+    mWaitingForContentResponse = false;
+    stateChanged = true;
+  }
+  return stateChanged;
+}
+
+bool PanGestureBlockState::HasReceivedAllContentNotifications() const {
+  return CancelableBlockState::HasReceivedAllContentNotifications() &&
+         !mWaitingForContentResponse;
+}
+
+bool PanGestureBlockState::IsReadyForHandling() const {
+  if (!CancelableBlockState::IsReadyForHandling()) {
+    return false;
+  }
+  return !mWaitingForContentResponse || IsContentResponseTimerExpired();
+}
+
+bool PanGestureBlockState::AllowScrollHandoff() const { return false; }
+
+void PanGestureBlockState::SetNeedsToWaitForContentResponse(
+    bool aWaitForContentResponse) {
+  mWaitingForContentResponse = aWaitForContentResponse;
+}
+
+PinchGestureBlockState::PinchGestureBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags)
+    : CancelableBlockState(aTargetApzc, aFlags),
+      mInterrupted(false),
+      mWaitingForContentResponse(false) {}
+
+bool PinchGestureBlockState::MustStayActive() { return true; }
+
+const char* PinchGestureBlockState::Type() { return "pinch gesture"; }
+
+bool PinchGestureBlockState::SetContentResponse(bool aPreventDefault) {
+  if (aPreventDefault) {
+    TBS_LOG("%p setting interrupted flag\n", this);
+    mInterrupted = true;
+  }
+  bool stateChanged = CancelableBlockState::SetContentResponse(aPreventDefault);
+  if (mWaitingForContentResponse) {
+    mWaitingForContentResponse = false;
+    stateChanged = true;
+  }
+  return stateChanged;
+}
+
+bool PinchGestureBlockState::HasReceivedAllContentNotifications() const {
+  return CancelableBlockState::HasReceivedAllContentNotifications() &&
+         !mWaitingForContentResponse;
+}
+
+bool PinchGestureBlockState::IsReadyForHandling() const {
+  if (!CancelableBlockState::IsReadyForHandling()) {
+    return false;
+  }
+  return !mWaitingForContentResponse || IsContentResponseTimerExpired();
+}
+
+void PinchGestureBlockState::SetNeedsToWaitForContentResponse(
+    bool aWaitForContentResponse) {
+  mWaitingForContentResponse = aWaitForContentResponse;
+}
+
+TouchBlockState::TouchBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc,
+    TargetConfirmationFlags aFlags, TouchCounter& aCounter)
+    : CancelableBlockState(aTargetApzc, aFlags),
+      mAllowedTouchBehaviorSet(false),
+      mDuringFastFling(false),
+      mSingleTapOccurred(false),
+      mInSlop(false),
+      mTouchCounter(aCounter),
+      mStartTime(GetTargetApzc()->GetFrameTime().Time()) {
+  TBS_LOG("Creating %p\n", this);
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    mAllowedTouchBehaviorSet = true;
+  }
+}
+
+bool TouchBlockState::SetAllowedTouchBehaviors(
+    const nsTArray<TouchBehaviorFlags>& aBehaviors) {
+  if (mAllowedTouchBehaviorSet) {
+    return false;
+  }
+  TBS_LOG("%p got allowed touch behaviours for %zu points\n", this,
+          aBehaviors.Length());
+  mAllowedTouchBehaviors.AppendElements(aBehaviors);
+  mAllowedTouchBehaviorSet = true;
+  return true;
+}
+
+bool TouchBlockState::GetAllowedTouchBehaviors(
+    nsTArray<TouchBehaviorFlags>& aOutBehaviors) const {
+  if (!mAllowedTouchBehaviorSet) {
+    return false;
+  }
+  aOutBehaviors.AppendElements(mAllowedTouchBehaviors);
+  return true;
+}
+
+bool TouchBlockState::HasAllowedTouchBehaviors() const {
+  return mAllowedTouchBehaviorSet;
+}
+
+void TouchBlockState::CopyPropertiesFrom(const TouchBlockState& aOther) {
+  TBS_LOG("%p copying properties from %p\n", this, &aOther);
+  if (StaticPrefs::layout_css_touch_action_enabled()) {
+    MOZ_ASSERT(aOther.mAllowedTouchBehaviorSet ||
+               aOther.IsContentResponseTimerExpired());
+    SetAllowedTouchBehaviors(aOther.mAllowedTouchBehaviors);
+  }
+  mTransformToApzc = aOther.mTransformToApzc;
+}
+
+bool TouchBlockState::HasReceivedAllContentNotifications() const {
+  return CancelableBlockState::HasReceivedAllContentNotifications()
+         // See comment in TouchBlockState::IsReadyforHandling()
+         && (!StaticPrefs::layout_css_touch_action_enabled() ||
+             mAllowedTouchBehaviorSet);
+}
+
+bool TouchBlockState::IsReadyForHandling() const {
+  if (!CancelableBlockState::IsReadyForHandling()) {
+    return false;
+  }
+
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    // If layout_css_touch_action_enabled() was false when this block was
+    // created, then mAllowedTouchBehaviorSet is guaranteed to the true.
+    // However, the pref may have been flipped to false after the block was
+    // created. In that case, we should eventually get the touch-behaviour
+    // notification, or expire the content response timeout, but we don't really
+    // need to wait for those, since we don't care about the touch-behaviour
+    // values any more.
+    return true;
+  }
+
+  return mAllowedTouchBehaviorSet || IsContentResponseTimerExpired();
+}
+
+void TouchBlockState::SetDuringFastFling() {
+  TBS_LOG("%p setting fast-motion flag\n", this);
+  mDuringFastFling = true;
+}
+
+bool TouchBlockState::IsDuringFastFling() const { return mDuringFastFling; }
+
+void TouchBlockState::SetSingleTapOccurred() {
+  TBS_LOG("%p setting single-tap-occurred flag\n", this);
+  mSingleTapOccurred = true;
+}
+
+bool TouchBlockState::SingleTapOccurred() const { return mSingleTapOccurred; }
+
+bool TouchBlockState::MustStayActive() { return true; }
+
+const char* TouchBlockState::Type() { return "touch"; }
+
+TimeDuration TouchBlockState::GetTimeSinceBlockStart() const {
+  return GetTargetApzc()->GetFrameTime().Time() - mStartTime;
+}
+
+void TouchBlockState::DispatchEvent(const InputData& aEvent) const {
+  MOZ_ASSERT(aEvent.mInputType == MULTITOUCH_INPUT);
+  mTouchCounter.Update(aEvent.AsMultiTouchInput());
+  CancelableBlockState::DispatchEvent(aEvent);
+}
+
+bool TouchBlockState::TouchActionAllowsPinchZoom() const {
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    return true;
+  }
+  // Pointer events specification requires that all touch points allow zoom.
+  for (size_t i = 0; i < mAllowedTouchBehaviors.Length(); i++) {
+    if (!(mAllowedTouchBehaviors[i] & AllowedTouchBehavior::PINCH_ZOOM)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool TouchBlockState::TouchActionAllowsDoubleTapZoom() const {
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    return true;
+  }
+  for (size_t i = 0; i < mAllowedTouchBehaviors.Length(); i++) {
+    if (!(mAllowedTouchBehaviors[i] & AllowedTouchBehavior::DOUBLE_TAP_ZOOM)) {
+      return false;
+    }
+  }
+  return true;
+}
+
+bool TouchBlockState::TouchActionAllowsPanningX() const {
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    return true;
+  }
+  if (mAllowedTouchBehaviors.IsEmpty()) {
+    // Default to allowed
+    return true;
+  }
+  TouchBehaviorFlags flags = mAllowedTouchBehaviors[0];
+  return (flags & AllowedTouchBehavior::HORIZONTAL_PAN);
+}
+
+bool TouchBlockState::TouchActionAllowsPanningY() const {
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    return true;
+  }
+  if (mAllowedTouchBehaviors.IsEmpty()) {
+    // Default to allowed
+    return true;
+  }
+  TouchBehaviorFlags flags = mAllowedTouchBehaviors[0];
+  return (flags & AllowedTouchBehavior::VERTICAL_PAN);
+}
+
+bool TouchBlockState::TouchActionAllowsPanningXY() const {
+  if (!StaticPrefs::layout_css_touch_action_enabled()) {
+    return true;
+  }
+  if (mAllowedTouchBehaviors.IsEmpty()) {
+    // Default to allowed
+    return true;
+  }
+  TouchBehaviorFlags flags = mAllowedTouchBehaviors[0];
+  return (flags & AllowedTouchBehavior::HORIZONTAL_PAN) &&
+         (flags & AllowedTouchBehavior::VERTICAL_PAN);
+}
+
+bool TouchBlockState::UpdateSlopState(const MultiTouchInput& aInput,
+                                      bool aApzcCanConsumeEvents) {
+  if (aInput.mType == MultiTouchInput::MULTITOUCH_START) {
+    // this is by definition the first event in this block. If it's the first
+    // touch, then we enter a slop state.
+    mInSlop = (aInput.mTouches.Length() == 1);
+    if (mInSlop) {
+      mSlopOrigin = aInput.mTouches[0].mScreenPoint;
+      TBS_LOG("%p entering slop with origin %s\n", this,
+              ToString(mSlopOrigin).c_str());
+    }
+    return false;
+  }
+  if (mInSlop) {
+    ScreenCoord threshold = 0;
+    // If the target was confirmed to null then the threshold doesn't
+    // matter anyway since the events will never be processed.
+    if (const RefPtr<AsyncPanZoomController>& apzc = GetTargetApzc()) {
+      threshold = aApzcCanConsumeEvents ? apzc->GetTouchStartTolerance()
+                                        : apzc->GetTouchMoveTolerance();
+    }
+    bool stayInSlop =
+        (aInput.mType == MultiTouchInput::MULTITOUCH_MOVE) &&
+        (aInput.mTouches.Length() == 1) &&
+        ((aInput.mTouches[0].mScreenPoint - mSlopOrigin).Length() < threshold);
+    if (!stayInSlop) {
+      // we're out of the slop zone, and will stay out for the remainder of
+      // this block
+      TBS_LOG("%p exiting slop\n", this);
+      mInSlop = false;
+    }
+  }
+  return mInSlop;
+}
+
+bool TouchBlockState::IsInSlop() const { return mInSlop; }
+
+Maybe<ScrollDirection> TouchBlockState::GetBestGuessPanDirection(
+    const MultiTouchInput& aInput) {
+  if (aInput.mType != MultiTouchInput::MULTITOUCH_MOVE ||
+      aInput.mTouches.Length() != 1) {
+    return Nothing();
+  }
+  ScreenPoint vector = aInput.mTouches[0].mScreenPoint - mSlopOrigin;
+  double angle = atan2(vector.y, vector.x);  // range [-pi, pi]
+  angle = fabs(angle);                       // range [0, pi]
+
+  double angleThreshold = TouchActionAllowsPanningXY()
+                              ? StaticPrefs::apz_axis_lock_lock_angle()
+                              : StaticPrefs::apz_axis_lock_direct_pan_angle();
+  if (apz::IsCloseToHorizontal(angle, angleThreshold)) {
+    return Some(ScrollDirection::eHorizontal);
+  }
+  if (apz::IsCloseToVertical(angle, angleThreshold)) {
+    return Some(ScrollDirection::eVertical);
+  }
+  return Nothing();
+}
+
+uint32_t TouchBlockState::GetActiveTouchCount() const {
+  return mTouchCounter.GetActiveTouchCount();
+}
+
+KeyboardBlockState::KeyboardBlockState(
+    const RefPtr<AsyncPanZoomController>& aTargetApzc)
+    : InputBlockState(aTargetApzc, TargetConfirmationFlags{true}) {}
+
+}  // namespace layers
+}  // namespace mozilla