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108 lines
3.5 KiB
C++
108 lines
3.5 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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/* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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/* implements DOM interface for querying and observing media queries */
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#ifndef mozilla_dom_MediaQueryList_h
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#define mozilla_dom_MediaQueryList_h
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#include "nsISupports.h"
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#include "nsCycleCollectionParticipant.h"
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#include "nsCOMPtr.h"
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#include "nsTArray.h"
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#include "mozilla/LinkedList.h"
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#include "mozilla/Attributes.h"
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#include "nsWrapperCache.h"
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#include "mozilla/DOMEventTargetHelper.h"
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#include "mozilla/dom/MediaQueryListBinding.h"
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namespace mozilla::dom {
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class MediaList;
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class MediaQueryList final : public DOMEventTargetHelper,
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public LinkedListElement<MediaQueryList> {
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public:
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// The caller who constructs is responsible for calling Evaluate
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// before calling any other methods.
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MediaQueryList(Document* aDocument, const nsACString& aMediaQueryList,
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CallerType);
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private:
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~MediaQueryList();
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public:
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NS_DECL_ISUPPORTS_INHERITED
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NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(MediaQueryList, DOMEventTargetHelper)
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nsISupports* GetParentObject() const;
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void MediaFeatureValuesChanged();
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// Returns whether we need to notify of the change by dispatching a change
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// event.
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[[nodiscard]] bool EvaluateOnRenderingUpdate();
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void FireChangeEvent();
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JSObject* WrapObject(JSContext* aCx,
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JS::Handle<JSObject*> aGivenProto) override;
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// WebIDL methods
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void GetMedia(nsACString& aMedia) const;
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bool Matches();
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void AddListener(EventListener* aListener);
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void RemoveListener(EventListener* aListener);
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IMPL_EVENT_HANDLER(change)
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bool HasListeners() const;
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void Disconnect();
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size_t SizeOfExcludingThis(MallocSizeOf aMallocSizeOf) const;
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private:
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void LastRelease() final {
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auto* listElement = static_cast<LinkedListElement<MediaQueryList>*>(this);
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if (listElement->isInList()) {
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listElement->remove();
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}
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}
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void RecomputeMatches();
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// We only need a pointer to the document to support lazy
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// reevaluation following dynamic changes. However, this lazy
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// reevaluation is perhaps somewhat important, since some usage
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// patterns may involve the creation of large numbers of
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// MediaQueryList objects which almost immediately become garbage
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// (after a single call to the .matches getter).
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//
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// This pointer does make us a little more dependent on cycle
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// collection.
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//
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// We have a non-null mDocument for our entire lifetime except
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// after cycle collection unlinking. Having a non-null mDocument
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// is equivalent to being in that document's mDOMMediaQueryLists
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// linked list.
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RefPtr<Document> mDocument;
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const RefPtr<const MediaList> mMediaList;
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// Whether our MediaList depends on our viewport size. Our medialist is
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// immutable, so we can just compute this once and carry on with our lives.
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const bool mViewportDependent : 1;
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// The matches state.
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// https://drafts.csswg.org/cssom-view/#mediaquerylist-matches-state
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bool mMatches : 1;
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// The value of the matches state on creation, or on the last rendering
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// update, in order to implement:
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// https://drafts.csswg.org/cssom-view/#evaluate-media-queries-and-report-changes
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bool mMatchesOnRenderingUpdate : 1;
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};
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} // namespace mozilla::dom
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#endif /* !defined(mozilla_dom_MediaQueryList_h) */
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