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
28namespace WebCore {
29
30class Document;
31class MediaQueryList;
32class MediaQueryListListener;
33class MediaQueryEvaluator;
34class MediaQuerySet;
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
41class MediaQueryMatcher : public RefCounted<MediaQueryMatcher> {
42public:
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 styleResolverChanged();
54    bool evaluate(const MediaQuerySet*);
55
56private:
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