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/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
/* 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/. */
/* 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 "prclist.h"
#include "mozilla/Attributes.h"
#include "nsWrapperCache.h"
#include "mozilla/dom/MediaQueryListBinding.h"
class nsIDocument;
class nsMediaList;
namespace mozilla {
namespace dom {
class MediaQueryList final : public nsISupports,
public nsWrapperCache,
public PRCList
{
public:
// The caller who constructs is responsible for calling Evaluate
// before calling any other methods.
MediaQueryList(nsIDocument *aDocument,
const nsAString &aMediaQueryList);
private:
~MediaQueryList();
public:
NS_DECL_CYCLE_COLLECTING_ISUPPORTS
NS_DECL_CYCLE_COLLECTION_SCRIPT_HOLDER_CLASS(MediaQueryList)
nsISupports* GetParentObject() const;
struct HandleChangeData {
RefPtr<MediaQueryList> mql;
RefPtr<mozilla::dom::MediaQueryListListener> callback;
};
// Appends listeners that need notification to aListenersToNotify
void MediumFeaturesChanged(nsTArray<HandleChangeData>& aListenersToNotify);
bool HasListeners() const { return !mCallbacks.IsEmpty(); }
void RemoveAllListeners();
JSObject* WrapObject(JSContext* aCx, JS::Handle<JSObject*> aGivenProto) override;
// WebIDL methods
void GetMedia(nsAString& aMedia);
bool Matches();
void AddListener(mozilla::dom::MediaQueryListListener& aListener);
void RemoveListener(mozilla::dom::MediaQueryListListener& aListener);
private:
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.
nsCOMPtr<nsIDocument> mDocument;
RefPtr<nsMediaList> mMediaList;
bool mMatches;
bool mMatchesValid;
nsTArray<RefPtr<mozilla::dom::MediaQueryListListener>> mCallbacks;
};
} // namespace dom
} // namespace mozilla
#endif /* !defined(mozilla_dom_MediaQueryList_h) */
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