core/display_lock/display_lock_context.cc

// Copyright 2018 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#include "third_party/blink/renderer/core/display_lock/display_lock_context.h"

#include <string>

#include "base/memory/ptr_util.h"
#include "base/metrics/histogram_macros.h"
#include "third_party/blink/renderer/core/accessibility/ax_object_cache.h"
#include "third_party/blink/renderer/core/css/style_change_reason.h"
#include "third_party/blink/renderer/core/css/style_recalc.h"
#include "third_party/blink/renderer/core/display_lock/display_lock_utilities.h"
#include "third_party/blink/renderer/core/display_lock/render_subtree_activation_event.h"
#include "third_party/blink/renderer/core/dom/document.h"
#include "third_party/blink/renderer/core/dom/dom_exception.h"
#include "third_party/blink/renderer/core/dom/element.h"
#include "third_party/blink/renderer/core/dom/node_computed_style.h"
#include "third_party/blink/renderer/core/editing/frame_selection.h"
#include "third_party/blink/renderer/core/editing/selection_template.h"
#include "third_party/blink/renderer/core/frame/local_frame_view.h"
#include "third_party/blink/renderer/core/html_element_type_helpers.h"
#include "third_party/blink/renderer/core/inspector/inspector_trace_events.h"
#include "third_party/blink/renderer/core/layout/layout_box.h"
#include "third_party/blink/renderer/core/layout/layout_object.h"
#include "third_party/blink/renderer/core/page/page.h"
#include "third_party/blink/renderer/core/paint/paint_layer.h"
#include "third_party/blink/renderer/core/paint/pre_paint_tree_walk.h"
#include "third_party/blink/renderer/platform/bindings/microtask.h"
#include "third_party/blink/renderer/platform/heap/heap.h"

namespace blink {

namespace {
namespace rejection_names {
const char* kContainmentNotSatisfied =
    "Containment requirement is not satisfied.";
const char* kUnsupportedDisplay =
    "Element has unsupported display type (display: contents).";
}  // namespace rejection_names

void RecordActivationReason(Document* document,
                            DisplayLockActivationReason reason) {
  int ordered_reason = -1;

  // IMPORTANT: This number needs to be bumped up when adding
  // new reasons.
  static const int number_of_reasons = 9;

  switch (reason) {
    case DisplayLockActivationReason::kAccessibility:
      ordered_reason = 0;
      break;
    case DisplayLockActivationReason::kFindInPage:
      ordered_reason = 1;
      break;
    case DisplayLockActivationReason::kFragmentNavigation:
      ordered_reason = 2;
      break;
    case DisplayLockActivationReason::kScriptFocus:
      ordered_reason = 3;
      break;
    case DisplayLockActivationReason::kScrollIntoView:
      ordered_reason = 4;
      break;
    case DisplayLockActivationReason::kSelection:
      ordered_reason = 5;
      break;
    case DisplayLockActivationReason::kSimulatedClick:
      ordered_reason = 6;
      break;
    case DisplayLockActivationReason::kUserFocus:
      ordered_reason = 7;
      break;
    case DisplayLockActivationReason::kViewportIntersection:
      ordered_reason = 8;
      break;
    case DisplayLockActivationReason::kViewport:
    case DisplayLockActivationReason::kAny:
      NOTREACHED();
      break;
  }
  UMA_HISTOGRAM_ENUMERATION("Blink.Render.DisplayLockActivationReason",
                            ordered_reason, number_of_reasons);

  if (document && reason == DisplayLockActivationReason::kFindInPage)
    document->MarkHasFindInPageSubtreeVisibilityActiveMatch();
}
}  // namespace

DisplayLockContext::DisplayLockContext(Element* element)
    : element_(element), document_(&element_->GetDocument()) {
  document_->AddDisplayLockContext(this);
  DetermineIfSubtreeHasFocus();
  DetermineIfSubtreeHasSelection();
}

void DisplayLockContext::SetRequestedState(ESubtreeVisibility state) {
  if (state_ == state)
    return;
  state_ = state;
  switch (state_) {
    case ESubtreeVisibility::kVisible:
      RequestUnlock();
      break;
    case ESubtreeVisibility::kAuto:
      RequestLock(static_cast<uint16_t>(DisplayLockActivationReason::kAny));
      break;
    case ESubtreeVisibility::kHidden:
      RequestLock(0u);
      break;
    case ESubtreeVisibility::kHiddenMatchable:
      RequestLock(
          static_cast<uint16_t>(DisplayLockActivationReason::kAny) &
          ~static_cast<uint16_t>(DisplayLockActivationReason::kViewport));
      break;
  }
  // In a new state, we might need to either start or stop observing viewport
  // intersections.
  UpdateActivationObservationIfNeeded();

  // If we needed a deferred not intersecting signal from 'auto' mode, we can
  // set that to false, since the mode has switched to something else. If we're
  // switching _to_ 'auto' mode, this should already be false and will be a
  // no-op.
  DCHECK(state_ != ESubtreeVisibility::kAuto ||
         !needs_deferred_not_intersecting_signal_);
  needs_deferred_not_intersecting_signal_ = false;
  UpdateLifecycleNotificationRegistration();

  // Note that we call this here since the |state_| change is a render affecting
  // state, but is tracked independently.
  NotifyRenderAffectingStateChanged();
}

void DisplayLockContext::AdjustElementStyle(ComputedStyle* style) const {
  if (state_ == ESubtreeVisibility::kVisible)
    return;
  // If not visible, element gains style and layout containment. If skipped, it
  // also gains size containment.
  // https://wicg.github.io/display-locking/#subtree-visibility
  auto contain = style->Contain() | kContainsStyle | kContainsLayout;
  if (IsLocked())
    contain |= kContainsSize;
  style->SetContain(contain);
}

void DisplayLockContext::RequestLock(uint16_t activation_mask) {
  UpdateActivationMask(activation_mask);
  SetRenderAffectingState(RenderAffectingState::kLockRequested, true);
}

void DisplayLockContext::RequestUnlock() {
  SetRenderAffectingState(RenderAffectingState::kLockRequested, false);
}

void DisplayLockContext::UpdateActivationMask(uint16_t activatable_mask) {
  if (activatable_mask == activatable_mask_)
    return;

  bool all_activation_was_blocked = !activatable_mask_;
  bool all_activation_is_blocked = !activatable_mask;
  UpdateDocumentBookkeeping(IsLocked(), all_activation_was_blocked, IsLocked(),
                            all_activation_is_blocked);

  activatable_mask_ = activatable_mask;
}

void DisplayLockContext::UpdateDocumentBookkeeping(
    bool was_locked,
    bool all_activation_was_blocked,
    bool is_locked,
    bool all_activation_is_blocked) {
  if (!document_)
    return;

  if (was_locked != is_locked) {
    if (is_locked)
      document_->AddLockedDisplayLock();
    else
      document_->RemoveLockedDisplayLock();
  }

  bool was_locked_and_blocking = was_locked && all_activation_was_blocked;
  bool is_locked_and_blocking = is_locked && all_activation_is_blocked;
  if (was_locked_and_blocking != is_locked_and_blocking) {
    if (is_locked_and_blocking)
      document_->IncrementDisplayLockBlockingAllActivation();
    else
      document_->DecrementDisplayLockBlockingAllActivation();
  }
}

void DisplayLockContext::UpdateActivationObservationIfNeeded() {
  // If we don't have a document, then we don't have an observer so just make
  // sure we're marked as not observing anything and early out.
  if (!document_) {
    is_observed_ = false;
    return;
  }

  // We require observation if we are in 'auto' mode and we're connected to a
  // view.
  bool should_observe =
      state_ == ESubtreeVisibility::kAuto && ConnectedToView();
  if (is_observed_ == should_observe)
    return;
  is_observed_ = should_observe;

  if (should_observe) {
    document_->RegisterDisplayLockActivationObservation(element_);
  } else {
    document_->UnregisterDisplayLockActivationObservation(element_);
    // If we're not listening to viewport intersections, then we can assume
    // we're not intersecting:
    // 1. We might not be connected, in which case we're not intersecting.
    // 2. We might not be in 'auto' mode. which means that this doesn't affect
    //    anything consequential but acts as a reset should we switch back to
    //    the 'auto' mode.
    SetRenderAffectingState(RenderAffectingState::kIntersectsViewport, false);
  }
}

bool DisplayLockContext::NeedsLifecycleNotifications() const {
  return needs_deferred_not_intersecting_signal_;
}

void DisplayLockContext::UpdateLifecycleNotificationRegistration() {
  if (!document_ || !document_->View()) {
    is_registered_for_lifecycle_notifications_ = false;
    return;
  }

  bool needs_notifications = NeedsLifecycleNotifications();
  if (needs_notifications == is_registered_for_lifecycle_notifications_)
    return;

  is_registered_for_lifecycle_notifications_ = needs_notifications;
  if (needs_notifications) {
    document_->View()->RegisterForLifecycleNotifications(this);
  } else {
    document_->View()->UnregisterFromLifecycleNotifications(this);
  }
}

void DisplayLockContext::Lock() {
  DCHECK(!IsLocked());
  is_locked_ = true;
  UpdateDocumentBookkeeping(false, !activatable_mask_, true,
                            !activatable_mask_);

  // If we're not connected, then we don't have to do anything else. Otherwise,
  // we need to ensure that we update our style to check for containment later,
  // layout size based on the options, and also clear the painted output.
  if (!ConnectedToView())
    return;

  // There are two ways we can get locked:
  // 1. A new subtree-visibility property needs us to be locked.
  // 2. We're in 'auto' mode and we are not intersecting the viewport.
  // In the first case, we are already in style processing, so we don't need to
  // invalidate style. However, in the second case we invalidate style so that
  // `AdjustElementStyle()` can be called.
  if (!document_->InStyleRecalc()) {
    element_->SetNeedsStyleRecalc(
        kLocalStyleChange,
        StyleChangeReasonForTracing::Create(style_change_reason::kDisplayLock));
  }

  // In either case, we schedule an animation. If we're already inside a
  // lifecycle update, this will be a no-op.
  ScheduleAnimation();

  // We need to notify the AX cache (if it exists) to update |element_|'s
  // children in the AX cache.
  if (AXObjectCache* cache = element_->GetDocument().ExistingAXObjectCache())
    cache->ChildrenChanged(element_);

  if (!element_->GetLayoutObject())
    return;

  // GraphicsLayer collection would normally skip layers if paint is blocked
  // by display-locking (see: CollectDrawableLayersForLayerListRecursively
  // in LocalFrameView). However, if we don't trigger this collection, then
  // we might use the cached result instead. In order to ensure we skip the
  // newly locked layers, we need to set |need_graphics_layer_collection_|
  // before marking the layer for repaint.
  if (!RuntimeEnabledFeatures::CompositeAfterPaintEnabled())
    needs_graphics_layer_collection_ = true;
  MarkPaintLayerNeedsRepaint();
}

// Should* and Did* function for the lifecycle phases. These functions control
// whether or not to process the lifecycle for self or for children.
// =============================================================================
bool DisplayLockContext::ShouldStyle(DisplayLockLifecycleTarget target) const {
  return !is_locked_ || target == DisplayLockLifecycleTarget::kSelf ||
         update_forced_ ||
         (document_->ActivatableDisplayLocksForced() &&
          IsActivatable(DisplayLockActivationReason::kAny));
}

void DisplayLockContext::DidStyle(DisplayLockLifecycleTarget target) {
  if (target == DisplayLockLifecycleTarget::kSelf) {
    // TODO(vmpstr): This needs to be in the spec.
    if (ForceUnlockIfNeeded())
      return;

    if (blocked_style_traversal_type_ == kStyleUpdateSelf)
      blocked_style_traversal_type_ = kStyleUpdateNotRequired;
  } else {
    if (element_->ChildNeedsReattachLayoutTree())
      element_->MarkAncestorsWithChildNeedsReattachLayoutTree();
    blocked_style_traversal_type_ = kStyleUpdateNotRequired;
    MarkElementsForWhitespaceReattachment();
  }
}

bool DisplayLockContext::ShouldLayout(DisplayLockLifecycleTarget target) const {
  return !is_locked_ || target == DisplayLockLifecycleTarget::kSelf ||
         update_forced_ ||
         (document_->ActivatableDisplayLocksForced() &&
          IsActivatable(DisplayLockActivationReason::kAny));
}

void DisplayLockContext::DidLayout(DisplayLockLifecycleTarget target) {
  if (target == DisplayLockLifecycleTarget::kSelf)
    return;
  // Since we did layout on children already, we'll clear this.
  child_layout_was_blocked_ = false;
}

bool DisplayLockContext::ShouldPrePaint(
    DisplayLockLifecycleTarget target) const {
  return !is_locked_ || target == DisplayLockLifecycleTarget::kSelf ||
         update_forced_;
}

void DisplayLockContext::DidPrePaint(DisplayLockLifecycleTarget target) {
  // This is here for symmetry, but could be removed if necessary.
}

bool DisplayLockContext::ShouldPaint(DisplayLockLifecycleTarget target) const {
  // Note that forced updates should never require us to paint, so we don't
  // check |update_forced_| here. In other words, although |update_forced_|
  // could be true here, we still should not paint. This also holds for
  // kUpdating state, since updates should not paint.
  return !is_locked_ || target == DisplayLockLifecycleTarget::kSelf;
}

void DisplayLockContext::DidPaint(DisplayLockLifecycleTarget) {
  // This is here for symmetry, but could be removed if necessary.
}
// End Should* and Did* functions ==============================================

bool DisplayLockContext::IsActivatable(
    DisplayLockActivationReason reason) const {
  return activatable_mask_ & static_cast<uint16_t>(reason);
}

void DisplayLockContext::FireActivationEvent(Element* activated_element) {
  DCHECK(RuntimeEnabledFeatures::CSSSubtreeVisibilityActivationEventEnabled());
  element_->DispatchEvent(
      *MakeGarbageCollected<RenderSubtreeActivationEvent>(*activated_element));
}

void DisplayLockContext::CommitForActivationWithSignal(
    Element* activated_element,
    DisplayLockActivationReason reason) {
  DCHECK(activated_element);
  DCHECK(element_);
  DCHECK(ConnectedToView());
  DCHECK(IsLocked());
  DCHECK(ShouldCommitForActivation(DisplayLockActivationReason::kAny));

  // TODO(vmpstr): Remove this when we have a beforematch event.
  if (RuntimeEnabledFeatures::CSSSubtreeVisibilityActivationEventEnabled()) {
    document_->EnqueueDisplayLockActivationTask(
        WTF::Bind(&DisplayLockContext::FireActivationEvent,
                  weak_factory_.GetWeakPtr(), WrapPersistent(activated_element)));
  }

  RecordActivationReason(document_, reason);
}

void DisplayLockContext::NotifyIsIntersectingViewport() {
  // If we are now intersecting, then we are definitely not nested in a locked
  // subtree and we don't need to lock as a result.
  needs_deferred_not_intersecting_signal_ = false;
  UpdateLifecycleNotificationRegistration();
  // If we're not connected, then there is no need to change any state.
  // This could be the case if we were disconnected while a viewport
  // intersection notification was pending.
  if (ConnectedToView())
    SetRenderAffectingState(RenderAffectingState::kIntersectsViewport, true);
}

void DisplayLockContext::NotifyIsNotIntersectingViewport() {
  if (IsLocked()) {
    DCHECK(!needs_deferred_not_intersecting_signal_);
    return;
  }

  // We might have been disconnected while the intersection observation
  // notification was pending. Ensure to unregister from lifecycle
  // notifications if we're doing that, and early out.
  if (!ConnectedToView()) {
    needs_deferred_not_intersecting_signal_ = false;
    UpdateLifecycleNotificationRegistration();
    return;
  }

  // There are two situations we need to consider here:
  // 1. We are off-screen but not nested in any other lock. This means we should
  //    re-lock (also verify that the reason we're in this state is that we're
  //    activated).
  // 2. We are in a nested locked context. This means we don't actually know
  //    whether we should lock or not. In order to avoid needless dirty of the
  //    layout and style trees up to the nested context, we remain unlocked.
  //    However, we also need to ensure that we relock if we become unnested.
  //    So, we simply delay this check to the next frame (via LocalFrameView),
  //    which will call this function again and so we can perform the check
  //    again.
  auto* locked_ancestor =
      DisplayLockUtilities::NearestLockedExclusiveAncestor(*element_);
  if (locked_ancestor) {
    needs_deferred_not_intersecting_signal_ = true;
  } else {
    needs_deferred_not_intersecting_signal_ = false;
    SetRenderAffectingState(RenderAffectingState::kIntersectsViewport, false);
  }
  UpdateLifecycleNotificationRegistration();
}

bool DisplayLockContext::ShouldCommitForActivation(
    DisplayLockActivationReason reason) const {
  return IsActivatable(reason) && IsLocked();
}

DisplayLockContext::ScopedForcedUpdate
DisplayLockContext::GetScopedForcedUpdate() {
  if (!is_locked_)
    return ScopedForcedUpdate(nullptr);

  DCHECK(!update_forced_);
  update_forced_ = true;
  TRACE_EVENT_NESTABLE_ASYNC_BEGIN0(
      TRACE_DISABLED_BY_DEFAULT("blink.debug.display_lock"), "LockForced",
      TRACE_ID_LOCAL(this));

  // Now that the update is forced, we should ensure that style layout, and
  // prepaint code can reach it via dirty bits. Note that paint isn't a part of
  // this, since |update_forced_| doesn't force paint to happen. See
  // ShouldPaint().
  MarkForStyleRecalcIfNeeded();
  MarkForLayoutIfNeeded();
  MarkAncestorsForPrePaintIfNeeded();
  return ScopedForcedUpdate(this);
}

void DisplayLockContext::NotifyForcedUpdateScopeEnded() {
  DCHECK(update_forced_);
  update_forced_ = false;
  TRACE_EVENT_NESTABLE_ASYNC_END0(
      TRACE_DISABLED_BY_DEFAULT("blink.debug.display_lock"), "LockForced",
      TRACE_ID_LOCAL(this));
}

void DisplayLockContext::Unlock() {
  DCHECK(IsLocked());
  is_locked_ = false;
  UpdateDocumentBookkeeping(true, !activatable_mask_, false,
                            !activatable_mask_);

  if (!ConnectedToView())
    return;

  ScheduleAnimation();

  // There are a few ways we can get unlocked:
  // 1. A new subtree-visibility property needs us to be ulocked.
  // 2. We're in 'auto' mode and we are intersecting the viewport.
  // 3. We're activating in hidden-matchable or auto mode
  // In the first case, we are already in style processing, so we don't need to
  // invalidate style. However, in the second and third cases we invalidate
  // style so that `AdjustElementStyle()` can be called.
  // TODO(vmpstr): Case 3 needs to be reworked, since the spec no longer has a
  // notion of activation.
  if (!document_->InStyleRecalc()) {
    // Since size containment depends on the activatability state, we should
    // invalidate the style for this element, so that the style adjuster can
    // properly remove the containment.
    element_->SetNeedsStyleRecalc(
        kLocalStyleChange,
        StyleChangeReasonForTracing::Create(style_change_reason::kDisplayLock));

    // Also propagate any dirty bits that we have previously blocked.
    // If we're in style recalc, this will be handled by
    // `AdjustStyleRecalcChangeForChildren()`.
    MarkForStyleRecalcIfNeeded();
  }

  // We also need to notify the AX cache (if it exists) to update the childrens
  // of |element_| in the AX cache.
  if (AXObjectCache* cache = element_->GetDocument().ExistingAXObjectCache())
    cache->ChildrenChanged(element_);

  auto* layout_object = element_->GetLayoutObject();
  // We might commit without connecting, so there is no layout object yet.
  if (!layout_object)
    return;

  // Now that we know we have a layout object, we should ensure that we can
  // reach the rest of the phases as well.
  MarkForLayoutIfNeeded();
  MarkAncestorsForPrePaintIfNeeded();
  MarkPaintLayerNeedsRepaint();
}

void DisplayLockContext::AddToWhitespaceReattachSet(Element& element) {
  whitespace_reattach_set_.insert(&element);
}

void DisplayLockContext::MarkElementsForWhitespaceReattachment() {
  for (auto element : whitespace_reattach_set_) {
    if (!element || element->NeedsReattachLayoutTree() ||
        !element->GetLayoutObject())
      continue;

    if (Node* first_child = LayoutTreeBuilderTraversal::FirstChild(*element))
      first_child->MarkAncestorsWithChildNeedsReattachLayoutTree();
  }
  whitespace_reattach_set_.clear();
}

StyleRecalcChange DisplayLockContext::AdjustStyleRecalcChangeForChildren(
    StyleRecalcChange change) {
  // This code is similar to MarkForStyleRecalcIfNeeded, except that it acts on
  // |change| and not on |element_|. This is only called during style recalc.
  // Note that since we're already in self style recalc, this code is shorter
  // since it doesn't have to deal with dirtying self-style.
  DCHECK(document_->InStyleRecalc());

  if (reattach_layout_tree_was_blocked_) {
    change = change.ForceReattachLayoutTree();
    reattach_layout_tree_was_blocked_ = false;
  }

  if (blocked_style_traversal_type_ == kStyleUpdateDescendants)
    change = change.ForceRecalcDescendants();
  else if (blocked_style_traversal_type_ == kStyleUpdateChildren)
    change = change.EnsureAtLeast(StyleRecalcChange::kRecalcChildren);
  blocked_style_traversal_type_ = kStyleUpdateNotRequired;
  return change;
}

bool DisplayLockContext::MarkForStyleRecalcIfNeeded() {
  if (reattach_layout_tree_was_blocked_) {
    // We previously blocked a layout tree reattachment on |element_|'s
    // descendants, so we should mark it for layout tree reattachment now.
    element_->SetForceReattachLayoutTree();
    reattach_layout_tree_was_blocked_ = false;
  }
  if (IsElementDirtyForStyleRecalc()) {
    if (blocked_style_traversal_type_ > kStyleUpdateNotRequired) {
      // We blocked a traversal going to the element previously.
      // Make sure we will traverse this element and maybe its subtree if we
      // previously blocked a style traversal that should've done that.
      element_->SetNeedsStyleRecalc(
          blocked_style_traversal_type_ == kStyleUpdateDescendants
              ? kSubtreeStyleChange
              : kLocalStyleChange,
          StyleChangeReasonForTracing::Create(
              style_change_reason::kDisplayLock));
      if (blocked_style_traversal_type_ == kStyleUpdateChildren)
        element_->SetChildNeedsStyleRecalc();
      blocked_style_traversal_type_ = kStyleUpdateNotRequired;
    } else if (element_->ChildNeedsReattachLayoutTree()) {
      // Mark |element_| as style dirty, as we can't mark for child reattachment
      // before style.
      element_->SetNeedsStyleRecalc(kLocalStyleChange,
                                    StyleChangeReasonForTracing::Create(
                                        style_change_reason::kDisplayLock));
    }
    // Propagate to the ancestors, since the dirty bit in a locked subtree is
    // stopped at the locked ancestor.
    // See comment in IsElementDirtyForStyleRecalc.
    element_->MarkAncestorsWithChildNeedsStyleRecalc();
    return true;
  }
  return false;
}

bool DisplayLockContext::MarkForLayoutIfNeeded() {
  if (IsElementDirtyForLayout()) {
    // Forces the marking of ancestors to happen, even if
    // |DisplayLockContext::ShouldLayout()| returns false.
    base::AutoReset<bool> scoped_force(&update_forced_, true);
    if (child_layout_was_blocked_) {
      // We've previously blocked a child traversal when doing self-layout for
      // the locked element, so we're marking it with child-needs-layout so that
      // it will traverse to the locked element and do the child traversal
      // again. We don't need to mark it for self-layout (by calling
      // |LayoutObject::SetNeedsLayout()|) because the locked element itself
      // doesn't need to relayout.
      element_->GetLayoutObject()->SetChildNeedsLayout();
      child_layout_was_blocked_ = false;
    } else {
      // Since the dirty layout propagation stops at the locked element, we need
      // to mark its ancestors as dirty here so that it will be traversed to on
      // the next layout.
      element_->GetLayoutObject()->MarkContainerChainForLayout();
    }
    return true;
  }
  return false;
}

bool DisplayLockContext::MarkAncestorsForPrePaintIfNeeded() {
  // TODO(vmpstr): We should add a compositing phase for proper bookkeeping.
  bool compositing_dirtied = MarkForCompositingUpdatesIfNeeded();

  if (IsElementDirtyForPrePaint()) {
    auto* layout_object = element_->GetLayoutObject();
    if (auto* parent = layout_object->Parent())
      parent->SetSubtreeShouldCheckForPaintInvalidation();

    // Note that if either we or our descendants are marked as needing this
    // update, then ensure to mark self as needing the update. This sets up the
    // correct flags for PrePaint to recompute the necessary values and
    // propagate the information into the subtree.
    if (needs_effective_allowed_touch_action_update_ ||
        layout_object->EffectiveAllowedTouchActionChanged() ||
        layout_object->DescendantEffectiveAllowedTouchActionChanged()) {
      // Note that although the object itself should have up to date value, in
      // order to force recalc of the whole subtree, we mark it as needing an
      // update.
      layout_object->MarkEffectiveAllowedTouchActionChanged();
    }
    return true;
  }
  return compositing_dirtied;
}

bool DisplayLockContext::MarkPaintLayerNeedsRepaint() {
  DCHECK(ConnectedToView());
  if (auto* layout_object = element_->GetLayoutObject()) {
    layout_object->PaintingLayer()->SetNeedsRepaint();
    if (!RuntimeEnabledFeatures::CompositeAfterPaintEnabled() &&
        needs_graphics_layer_collection_) {
      document_->View()->SetForeignLayerListNeedsUpdate();
      needs_graphics_layer_collection_ = false;
    }
    return true;
  }
  return false;
}

bool DisplayLockContext::MarkForCompositingUpdatesIfNeeded() {
  if (!ConnectedToView())
    return false;

  auto* layout_object = element_->GetLayoutObject();
  if (!layout_object)
    return false;

  auto* layout_box = DynamicTo<LayoutBoxModelObject>(layout_object);
  if (layout_box && layout_box->HasSelfPaintingLayer()) {
    if (layout_box->Layer()->ChildNeedsCompositingInputsUpdate() &&
        layout_box->Layer()->Parent()) {
      // Note that if the layer's child needs compositing inputs update, then
      // that layer itself also needs compositing inputs update. In order to
      // propagate the dirty bit, we need to mark this layer's _parent_ as a
      // needing an update.
      layout_box->Layer()->Parent()->SetNeedsCompositingInputsUpdate();
    }
    if (needs_compositing_requirements_update_)
      layout_box->Layer()->SetNeedsCompositingRequirementsUpdate();
    needs_compositing_requirements_update_ = false;
    return true;
  }
  return false;
}

bool DisplayLockContext::IsElementDirtyForStyleRecalc() const {
  // The |element_| checks could be true even if |blocked_style_traversal_type_|
  // is not required. The reason for this is that the
  // blocked_style_traversal_type_ is set during the style walk that this
  // display lock blocked. However, we could dirty element style and commit
  // before ever having gone through the style calc that would have been
  // blocked, meaning we never blocked style during a walk. Instead we might
  // have not propagated the dirty bits up the tree.
  return element_->NeedsStyleRecalc() || element_->ChildNeedsStyleRecalc() ||
         element_->ChildNeedsReattachLayoutTree() ||
         blocked_style_traversal_type_ > kStyleUpdateNotRequired;
}

bool DisplayLockContext::IsElementDirtyForLayout() const {
  if (auto* layout_object = element_->GetLayoutObject())
    return layout_object->NeedsLayout() || child_layout_was_blocked_;
  return false;
}

bool DisplayLockContext::IsElementDirtyForPrePaint() const {
  if (auto* layout_object = element_->GetLayoutObject()) {
    auto* layout_box = DynamicTo<LayoutBoxModelObject>(layout_object);
    return PrePaintTreeWalk::ObjectRequiresPrePaint(*layout_object) ||
           PrePaintTreeWalk::ObjectRequiresTreeBuilderContext(*layout_object) ||
           needs_prepaint_subtree_walk_ ||
           needs_effective_allowed_touch_action_update_ ||
           needs_compositing_requirements_update_ ||
           (layout_box && layout_box->HasSelfPaintingLayer() &&
            layout_box->Layer()->ChildNeedsCompositingInputsUpdate());
  }
  return false;
}

void DisplayLockContext::DidMoveToNewDocument(Document& old_document) {
  DCHECK(element_);
  document_ = &element_->GetDocument();

  old_document.RemoveDisplayLockContext(this);
  document_->AddDisplayLockContext(this);

  if (is_observed_) {
    old_document.UnregisterDisplayLockActivationObservation(element_);
    document_->RegisterDisplayLockActivationObservation(element_);
  }

  // Since we're observing the lifecycle updates, ensure that we listen to the
  // right document's view.
  if (is_registered_for_lifecycle_notifications_) {
    if (old_document.View())
      old_document.View()->UnregisterFromLifecycleNotifications(this);

    if (document_->View())
      document_->View()->RegisterForLifecycleNotifications(this);
    else
      is_registered_for_lifecycle_notifications_ = false;
  }

  if (IsLocked()) {
    old_document.RemoveLockedDisplayLock();
    document_->AddLockedDisplayLock();
    if (!IsActivatable(DisplayLockActivationReason::kAny)) {
      old_document.DecrementDisplayLockBlockingAllActivation();
      document_->IncrementDisplayLockBlockingAllActivation();
    }
  }

  DetermineIfSubtreeHasFocus();
  DetermineIfSubtreeHasSelection();
}

void DisplayLockContext::WillStartLifecycleUpdate(const LocalFrameView& view) {
  DCHECK(NeedsLifecycleNotifications());
  // We might have delayed processing intersection observation update (signal
  // that we were not intersecting) because this context was nested in another
  // locked context. At the start of the lifecycle, we should check whether
  // that is still true. In other words, this call will check if we're still
  // nested. If we are, we won't do anything. If we're not, then we will lock
  // this context.
  //
  // Note that when we are no longer nested and and we have not received any
  // notifications from the intersection observer, it means that we are not
  // visible.
  if (needs_deferred_not_intersecting_signal_)
    NotifyIsNotIntersectingViewport();
}

void DisplayLockContext::NotifyWillDisconnect() {
  if (!IsLocked() || !element_ || !element_->GetLayoutObject())
    return;
  // If we're locked while being disconnected, we need to layout the parent.
  // The reason for this is that we might skip the layout if we're empty while
  // locked, but it's important to update IsSelfCollapsingBlock property on
  // the parent so that it's up to date. This property is updated during
  // layout.
  if (auto* parent = element_->GetLayoutObject()->Parent())
    parent->SetNeedsLayout(layout_invalidation_reason::kDisplayLock);
}

void DisplayLockContext::ElementDisconnected() {
  UpdateActivationObservationIfNeeded();
}

void DisplayLockContext::ElementConnected() {
  UpdateActivationObservationIfNeeded();
  DetermineIfSubtreeHasFocus();
  DetermineIfSubtreeHasSelection();
}

void DisplayLockContext::ScheduleAnimation() {
  DCHECK(element_);
  if (!ConnectedToView() || !document_ || !document_->GetPage())
    return;

  // Schedule an animation to perform the lifecycle phases.
  document_->GetPage()->Animator().ScheduleVisualUpdate(document_->GetFrame());
}

const char* DisplayLockContext::ShouldForceUnlock() const {
  DCHECK(element_);
  // This function is only called after style, layout tree, or lifecycle
  // updates, so the style should be up-to-date, except in the case of nested
  // locks, where the style recalc will never actually get to |element_|.
  // TODO(vmpstr): We need to figure out what to do here, since we don't know
  // what the style is and whether this element has proper containment. However,
  // forcing an update from the ancestor locks seems inefficient. For now, we
  // just optimistically assume that we have all of the right containment in
  // place. See crbug.com/926276 for more information.
  if (element_->NeedsStyleRecalc()) {
    DCHECK(DisplayLockUtilities::NearestLockedExclusiveAncestor(*element_));
    return nullptr;
  }

  if (element_->HasDisplayContentsStyle())
    return rejection_names::kUnsupportedDisplay;

  auto* style = element_->GetComputedStyle();
  // Note that if for whatever reason we don't have computed style, then
  // optimistically assume that we have containment.
  if (!style)
    return nullptr;
  if (!style->ContainsStyle() || !style->ContainsLayout())
    return rejection_names::kContainmentNotSatisfied;

  // We allow replaced elements to be locked. This check is similar to the check
  // in DefinitelyNewFormattingContext() in element.cc, but in this case we
  // allow object element to get locked.
  if (IsA<HTMLObjectElement>(*element_) || IsA<HTMLImageElement>(*element_) ||
      element_->IsFormControlElement() || element_->IsMediaElement() ||
      element_->IsFrameOwnerElement() || element_->IsSVGElement()) {
    return nullptr;
  }

  // From https://www.w3.org/TR/css-contain-1/#containment-layout
  // If the element does not generate a principal box (as is the case with
  // display: contents or display: none), or if the element is an internal
  // table element other than display: table-cell, if the element is an
  // internal ruby element, or if the element’s principal box is a
  // non-atomic inline-level box, layout containment has no effect.
  // (Note we're allowing display:none for display locked elements, and a bit
  // more restrictive on ruby - banning <ruby> elements entirely).
  auto* html_element = DynamicTo<HTMLElement>(element_.Get());
  if ((style->IsDisplayTableType() &&
       style->Display() != EDisplay::kTableCell) ||
      (!html_element || IsA<HTMLRubyElement>(html_element)) ||
      (style->IsDisplayInlineType() && !style->IsDisplayReplacedType())) {
    return rejection_names::kContainmentNotSatisfied;
  }
  return nullptr;
}

bool DisplayLockContext::ForceUnlockIfNeeded() {
  // We must have "contain: style layout", and disallow display:contents
  // for display locking. Note that we should always guarantee this after
  // every style or layout tree update. Otherwise, proceeding with layout may
  // cause unexpected behavior. By rejecting the promise, the behavior can be
  // detected by script.
  // TODO(rakina): If this is after acquire's promise is resolved and update()
  // commit() isn't in progress, the web author won't know that the element
  // got unlocked. Figure out how to notify the author.
  if (auto* reason = ShouldForceUnlock()) {
    is_locked_ = false;
    return true;
  }
  return false;
}

bool DisplayLockContext::ConnectedToView() const {
  return element_ && document_ && element_->isConnected() && document_->View();
}

void DisplayLockContext::NotifySubtreeLostFocus() {
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasFocus, false);
}

void DisplayLockContext::NotifySubtreeGainedFocus() {
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasFocus, true);
}

void DisplayLockContext::DetermineIfSubtreeHasFocus() {
  if (!ConnectedToView()) {
    SetRenderAffectingState(RenderAffectingState::kSubtreeHasFocus, false);
    return;
  }

  bool subtree_has_focus = false;
  // Iterate up the ancestor chain from the currently focused element. If at any
  // time we find our element, then our subtree is focused.
  for (auto* focused = document_->FocusedElement(); focused;
       focused = FlatTreeTraversal::ParentElement(*focused)) {
    if (focused == element_.Get()) {
      subtree_has_focus = true;
      break;
    }
  }
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasFocus,
                          subtree_has_focus);
}

void DisplayLockContext::NotifySubtreeGainedSelection() {
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasSelection, true);
}

void DisplayLockContext::NotifySubtreeLostSelection() {
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasSelection, false);
}

void DisplayLockContext::DetermineIfSubtreeHasSelection() {
  if (!ConnectedToView() || !document_->GetFrame()) {
    SetRenderAffectingState(RenderAffectingState::kSubtreeHasSelection, false);
    return;
  }

  auto range = ToEphemeralRangeInFlatTree(document_->GetFrame()
                                              ->Selection()
                                              .GetSelectionInDOMTree()
                                              .ComputeRange());
  bool subtree_has_selection = false;
  for (auto& node : range.Nodes()) {
    for (auto& ancestor : FlatTreeTraversal::InclusiveAncestorsOf(node)) {
      if (&ancestor == element_.Get()) {
        subtree_has_selection = true;
        break;
      }
    }
    if (subtree_has_selection)
      break;
  }
  SetRenderAffectingState(RenderAffectingState::kSubtreeHasSelection,
                          subtree_has_selection);
}

void DisplayLockContext::SetRenderAffectingState(RenderAffectingState state,
                                                 bool new_flag) {
  render_affecting_state_[static_cast<int>(state)] = new_flag;
  NotifyRenderAffectingStateChanged();
}

void DisplayLockContext::NotifyRenderAffectingStateChanged() {
  auto state = [this](RenderAffectingState state) {
    return render_affecting_state_[static_cast<int>(state)];
  };

  // Check that we're visible if and only if lock has not been requested.
  DCHECK(state_ == ESubtreeVisibility::kVisible ||
         state(RenderAffectingState::kLockRequested));
  DCHECK(state_ != ESubtreeVisibility::kVisible ||
         !state(RenderAffectingState::kLockRequested));

  // We should be locked if the lock has been requested (the above DCHECKs
  // verify that this means that we are not 'visible'), and any of the
  // following is true:
  // - We are not in 'auto' mode (meaning 'hidden') or
  // - We are in 'auto' mode and nothing blocks locking: viewport is
  //   not intersecting, subtree doesn't have focus, and subtree doesn't have
  //   selection.
  bool should_be_locked =
      state(RenderAffectingState::kLockRequested) &&
      (state_ != ESubtreeVisibility::kAuto ||
       (!state(RenderAffectingState::kIntersectsViewport) &&
        !state(RenderAffectingState::kSubtreeHasFocus) &&
        !state(RenderAffectingState::kSubtreeHasSelection)));

  if (should_be_locked && !IsLocked())
    Lock();
  else if (!should_be_locked && IsLocked())
    Unlock();
}

void DisplayLockContext::Trace(Visitor* visitor) {
  visitor->Trace(element_);
  visitor->Trace(document_);
  visitor->Trace(whitespace_reattach_set_);
}

// Scoped objects implementation
// -----------------------------------------------
DisplayLockContext::ScopedForcedUpdate::ScopedForcedUpdate(
    DisplayLockContext* context)
    : context_(context) {}

DisplayLockContext::ScopedForcedUpdate::ScopedForcedUpdate(
    ScopedForcedUpdate&& other)
    : context_(other.context_) {
  other.context_ = nullptr;
}

DisplayLockContext::ScopedForcedUpdate::~ScopedForcedUpdate() {
  if (context_)
    context_->NotifyForcedUpdateScopeEnded();
}

}  // namespace blink