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      1 /*
      2  * Copyright (C) 2010 Nokia Corporation and/or its subsidiary(-ies)
      3  *
      4  *  This library is free software; you can redistribute it and/or
      5  *  modify it under the terms of the GNU Library General Public
      6  *  License as published by the Free Software Foundation; either
      7  *  version 2 of the License, or (at your option) any later version.
      8  *
      9  *  This library is distributed in the hope that it will be useful,
     10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
     11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     12  *  Library General Public License for more details.
     13  *
     14  *  You should have received a copy of the GNU Library General Public License
     15  *  along with this library; see the file COPYING.LIB.  If not, write to
     16  *  the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
     17  *  Boston, MA 02110-1301, USA.
     18  */
     19 
     20 #ifndef MediaQueryMatcher_h
     21 #define MediaQueryMatcher_h
     22 
     23 #include "ScriptState.h"
     24 #include <wtf/Forward.h>
     25 #include <wtf/RefCounted.h>
     26 #include <wtf/Vector.h>
     27 
     28 namespace WebCore {
     29 
     30 class Document;
     31 class MediaList;
     32 class MediaQueryList;
     33 class MediaQueryListListener;
     34 class MediaQueryEvaluator;
     35 
     36 // MediaQueryMatcher class is responsible for keeping a vector of pairs
     37 // MediaQueryList x MediaQueryListListener. It is responsible for evaluating the queries
     38 // whenever it is needed and to call the listeners if the corresponding query has changed.
     39 // The listeners must be called in the very same order in which they have been added.
     40 
     41 class MediaQueryMatcher : public RefCounted<MediaQueryMatcher> {
     42 public:
     43     static PassRefPtr<MediaQueryMatcher> create(Document* document) { return adoptRef(new MediaQueryMatcher(document)); }
     44     ~MediaQueryMatcher();
     45     void documentDestroyed();
     46 
     47     void addListener(PassRefPtr<MediaQueryListListener>, PassRefPtr<MediaQueryList>);
     48     void removeListener(MediaQueryListListener*, MediaQueryList*);
     49 
     50     PassRefPtr<MediaQueryList> matchMedia(const String&);
     51 
     52     unsigned evaluationRound() const { return m_evaluationRound; }
     53     void styleSelectorChanged();
     54     bool evaluate(MediaList*);
     55 
     56 private:
     57     class Listener {
     58     public:
     59         Listener(PassRefPtr<MediaQueryListListener>, PassRefPtr<MediaQueryList>);
     60         ~Listener();
     61 
     62         void evaluate(ScriptState*, MediaQueryEvaluator*);
     63 
     64         MediaQueryListListener* listener() { return m_listener.get(); }
     65         MediaQueryList* query() { return m_query.get(); }
     66 
     67     private:
     68         RefPtr<MediaQueryListListener> m_listener;
     69         RefPtr<MediaQueryList> m_query;
     70     };
     71 
     72     MediaQueryMatcher(Document*);
     73     PassOwnPtr<MediaQueryEvaluator> prepareEvaluator() const;
     74     String mediaType() const;
     75 
     76     Document* m_document;
     77     Vector<OwnPtr<Listener> > m_listeners;
     78 
     79     // This value is incremented at style selector changes.
     80     // It is used to avoid evaluating queries more then once and to make sure
     81     // that a media query result change is notified exactly once.
     82     unsigned m_evaluationRound;
     83 };
     84 
     85 }
     86 
     87 #endif // MediaQueryMatcher_h
     88