author Kris Maglione <>
Wed, 13 Feb 2019 20:50:10 -0800
changeset 516999 68cffca6927a90ace041bd3f938954fab0d0c586
parent 509549 f0a91d36587266d7454a450c6044d573664fbed5
permissions -rw-r--r--
Bug 1524687: Follow-up: Fix sporadic Windows PGO build bustages. r=bustage CLOSED TREE

/* -*- 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 {
namespace dom {

class MediaList;

class MediaQueryList final : public DOMEventTargetHelper,
                             public mozilla::LinkedListElement<MediaQueryList> {
  // The caller who constructs is responsible for calling Evaluate
  // before calling any other methods.
  MediaQueryList(Document* aDocument, const nsAString& aMediaQueryList,
                 CallerType aCallerType);



  nsISupports* GetParentObject() const;

  void MaybeNotify();

  JSObject* WrapObject(JSContext* aCx,
                       JS::Handle<JSObject*> aGivenProto) override;

  // WebIDL methods
  void GetMedia(nsAString& aMedia);
  bool Matches();
  void AddListener(EventListener* aListener, ErrorResult& aRv);
  void RemoveListener(EventListener* aListener, ErrorResult& aRv);

  using DOMEventTargetHelper::EventListenerAdded;
  void EventListenerAdded(nsAtom* aType) override;


  bool HasListeners();

  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;

  RefPtr<MediaList> mMediaList;
  bool mMatches;
  bool mMatchesValid;

}  // namespace dom
}  // namespace mozilla

#endif /* !defined(mozilla_dom_MediaQueryList_h) */