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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 */
/* implements DOM interface for querying and observing media queries */
#ifndef mozilla_dom_MediaQueryList_h
#define mozilla_dom_MediaQueryList_h
#include "nsISupports.h"
#include "nsCycleCollectionParticipant.h"
#include "nsCOMPtr.h"
#include "nsTArray.h"
#include "mozilla/LinkedList.h"
#include "mozilla/Attributes.h"
#include "nsWrapperCache.h"
#include "mozilla/DOMEventTargetHelper.h"
#include "mozilla/dom/MediaQueryListBinding.h"
namespace mozilla::dom {
class MediaList;
class MediaQueryList final : public DOMEventTargetHelper,
public LinkedListElement<MediaQueryList> {
// The caller who constructs is responsible for calling Evaluate
// before calling any other methods.
MediaQueryList(Document* aDocument, const nsACString& aMediaQueryList,
nsISupports* GetParentObject() const;
void MediaFeatureValuesChanged();
// Returns whether we need to notify of the change by dispatching a change
// event.
[[nodiscard]] bool EvaluateOnRenderingUpdate();
void FireChangeEvent();
JSObject* WrapObject(JSContext* aCx,
JS::Handle<JSObject*> aGivenProto) override;
// WebIDL methods
void GetMedia(nsACString& aMedia) const;
bool Matches();
void AddListener(EventListener* aListener, ErrorResult& aRv);
void RemoveListener(EventListener* aListener, ErrorResult& aRv);
bool HasListeners() const;
void Disconnect();
size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
void LastRelease() final {
auto* listElement = static_cast<LinkedListElement<MediaQueryList>*>(this);
if (listElement->isInList()) {
void RecomputeMatches();
// We only need a pointer to the document to support lazy
// reevaluation following dynamic changes. However, this lazy
// reevaluation is perhaps somewhat important, since some usage
// patterns may involve the creation of large numbers of
// MediaQueryList objects which almost immediately become garbage
// (after a single call to the .matches getter).
// This pointer does make us a little more dependent on cycle
// collection.
// We have a non-null mDocument for our entire lifetime except
// after cycle collection unlinking. Having a non-null mDocument
// is equivalent to being in that document's mDOMMediaQueryLists
// linked list.
RefPtr<Document> mDocument;
const RefPtr<const MediaList> mMediaList;
// Whether our MediaList depends on our viewport size. Our medialist is
// immutable, so we can just compute this once and carry on with our lives.
const bool mViewportDependent : 1;
// The matches state.
bool mMatches : 1;
// The value of the matches state on creation, or on the last rendering
// update, in order to implement:
bool mMatchesOnRenderingUpdate : 1;
} // namespace mozilla::dom
#endif /* !defined(mozilla_dom_MediaQueryList_h) */