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// Copyright 2020 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.
#ifndef THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_DISPLAY_LOCK_DOCUMENT_STATE_H_
#define THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_DISPLAY_LOCK_DOCUMENT_STATE_H_
#include "third_party/blink/renderer/core/core_export.h"
#include "third_party/blink/renderer/core/display_lock/display_lock_utilities.h"
#include "third_party/blink/renderer/platform/heap/heap.h"
#include "third_party/blink/renderer/platform/heap/heap_allocator.h"
#include "third_party/blink/renderer/platform/heap/member.h"
namespace blink {
class DisplayLockContext;
class Document;
class Element;
class IntersectionObserver;
class IntersectionObserverEntry;
// This class is responsible for keeping document level state for the display
// locking feature.
class CORE_EXPORT DisplayLockDocumentState final
: public GarbageCollected<DisplayLockDocumentState> {
public:
explicit DisplayLockDocumentState(Document* document);
// GC.
void Trace(Visitor*);
// Registers a display lock context with the state. This is used to force all
// activatable locks.
void AddDisplayLockContext(DisplayLockContext*);
void RemoveDisplayLockContext(DisplayLockContext*);
int DisplayLockCount() const;
// Bookkeeping: the count of all locked display locks.
void AddLockedDisplayLock();
void RemoveLockedDisplayLock();
int LockedDisplayLockCount() const;
// Bookkeeping: the count of all locked display locks which block all
// activation (i.e. content-visibility: hidden locks).
void IncrementDisplayLockBlockingAllActivation();
void DecrementDisplayLockBlockingAllActivation();
int DisplayLockBlockingAllActivationCount() const;
// Register the given element for intersection observation. Used for detecting
// viewport intersections for content-visibility: auto locks.
void RegisterDisplayLockActivationObservation(Element*);
void UnregisterDisplayLockActivationObservation(Element*);
// Returns true if all activatable locks have been forced.
bool ActivatableDisplayLocksForced() const;
class ScopedForceActivatableDisplayLocks {
STACK_ALLOCATED();
public:
ScopedForceActivatableDisplayLocks(ScopedForceActivatableDisplayLocks&&);
~ScopedForceActivatableDisplayLocks();
ScopedForceActivatableDisplayLocks& operator=(
ScopedForceActivatableDisplayLocks&&);
private:
friend DisplayLockDocumentState;
explicit ScopedForceActivatableDisplayLocks(DisplayLockDocumentState*);
DisplayLockDocumentState* state_;
};
ScopedForceActivatableDisplayLocks GetScopedForceActivatableLocks();
// Notify the display locks that selection was removed.
void NotifySelectionRemoved();
// This is called when the ScopedChainForcedUpdate is created or destroyed.
// This is used to ensure that we can create new locks that are immediately
// forced by the existing forced scope.
//
// Consider the situation A -> B -> C, where C is the child node which is the
// target of the forced lock (the parameter passed here), and B is its parent
// and A is its grandparent. Suppose that A and B have locks, but since style
// was blocked by A, B's lock has not been created yet. When we force the
// update from C we call `NotifyNodeForced()`, and A's lock is forced by the
// given ScopedChainForcedUpdate. Then we process the style and while
// processing B's style, we find that there is a new lock there. This lock
// needs to be forced immediately, since it is in the ancestor chain of C.
// This is done by calling `ForceLockIfNeeded()` below, which adds B's scope
// to the chain. At the end of the scope, everything is un-forced and
// `EndNodeForcedScope()` is called to clean up state.
//
// Note that there can only be one scope created at a time, so we don't keep
// track of more than one of these scopes. This is enforced by private access
// modifier + friends, as well as DCHECKs.
void BeginNodeForcedScope(
const Node* node,
bool self_was_forced,
DisplayLockUtilities::ScopedChainForcedUpdate* scope);
void EndNodeForcedScope(DisplayLockUtilities::ScopedChainForcedUpdate* scope);
// Forces the lock on the given element, if it isn't yet forced but appears on
// the ancestor chain for the forced element (which was set via
// `BeginNodeForcedScope()`).
void ForceLockIfNeeded(Element*);
private:
struct ForcedNodeInfo {
ForcedNodeInfo(const Node* node,
bool self_forced,
DisplayLockUtilities::ScopedChainForcedUpdate* scope)
: node(node), self_forced(self_forced), scope(scope) {}
// Since this is created via a Scoped stack-only object, we know that GC
// won't run so this is safe to store as an untraced member.
UntracedMember<const Node> node;
bool self_forced;
DisplayLockUtilities::ScopedChainForcedUpdate* scope;
};
IntersectionObserver& EnsureIntersectionObserver();
void ProcessDisplayLockActivationObservation(
const HeapVector<Member<IntersectionObserverEntry>>&);
void ForceLockIfNeededForInfo(Element*, ForcedNodeInfo*);
// Note that since this class is owned by the document, it is important not to
// take a strong reference for the backpointer.
WeakMember<Document> document_ = nullptr;
Member<IntersectionObserver> intersection_observer_ = nullptr;
HeapHashSet<WeakMember<DisplayLockContext>> display_lock_contexts_;
int locked_display_lock_count_ = 0;
int display_lock_blocking_all_activation_count_ = 0;
// If greater than 0, then the activatable locks are forced.
int activatable_display_locks_forced_ = 0;
// Contains all of the currently forced node infos, each of which represents
// the node that caused the scope to be created.
Vector<ForcedNodeInfo> forced_node_info_;
};
} // namespace blink
#endif // THIRD_PARTY_BLINK_RENDERER_CORE_DISPLAY_LOCK_DISPLAY_LOCK_DOCUMENT_STATE_H_