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80 lines
2.5 KiB
C++
80 lines
2.5 KiB
C++
/* vim: set shiftwidth=2 tabstop=8 autoindent cindent expandtab: */
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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 nsDOMMediaQueryList_h_
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#define nsDOMMediaQueryList_h_
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#include "nsIDOMMediaQueryList.h"
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#include "nsCycleCollectionParticipant.h"
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#include "nsAutoPtr.h"
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#include "nsCOMPtr.h"
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#include "nsTArray.h"
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#include "prclist.h"
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#include "mozilla/Attributes.h"
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class nsPresContext;
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class nsMediaList;
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class nsDOMMediaQueryList MOZ_FINAL : public nsIDOMMediaQueryList,
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public PRCList
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{
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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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nsDOMMediaQueryList(nsPresContext *aPresContext,
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const nsAString &aMediaQueryList);
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private:
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~nsDOMMediaQueryList();
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public:
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NS_DECL_CYCLE_COLLECTING_ISUPPORTS
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NS_DECL_CYCLE_COLLECTION_CLASS(nsDOMMediaQueryList)
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NS_DECL_NSIDOMMEDIAQUERYLIST
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struct HandleChangeData {
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nsRefPtr<nsDOMMediaQueryList> mql;
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nsCOMPtr<nsIDOMMediaQueryListListener> listener;
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};
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typedef FallibleTArray< nsCOMPtr<nsIDOMMediaQueryListListener> > ListenerList;
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typedef FallibleTArray<HandleChangeData> NotifyList;
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// Appends listeners that need notification to aListenersToNotify
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void MediumFeaturesChanged(NotifyList &aListenersToNotify);
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bool HasListeners() const { return !mListeners.IsEmpty(); }
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void RemoveAllListeners();
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private:
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void RecomputeMatches();
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// We only need a pointer to the pres context 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 mPresContext for our entire lifetime except
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// after cycle collection unlinking. Having a non-null mPresContext
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// is equivalent to being in that pres context's mDOMMediaQueryLists
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// linked list.
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nsRefPtr<nsPresContext> mPresContext;
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nsRefPtr<nsMediaList> mMediaList;
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bool mMatches;
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bool mMatchesValid;
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ListenerList mListeners;
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};
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#endif /* !defined(nsDOMMediaQueryList_h_) */
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