src/engineobserver.h

   1 /***************************************************************************
   2                       engineobserver.h  -  Observer pattern for engine
   3                          -------------------
   4 begin                : Mar 14 2003
   5 copyright            : (C) 2003 by Frederik Holljen
   6 email                : fh@ez.no
   7 ***************************************************************************/
   8
   9 /***************************************************************************
  10  *                                                                         *
  11  *   This program is free software; you can redistribute it and/or modify  *
  12  *   it under the terms of the GNU General Public License as published by  *
  13  *   the Free Software Foundation; either version 2 of the License, or     *
  14  *   (at your option) any later version.                                   *
  15  *                                                                         *
  16  ***************************************************************************/
  17
  18 #ifndef AMAROK_ENGINEOBSERVER_H
  19 #define AMAROK_ENGINEOBSERVER_H
  20
  21 #include "amarok_export.h"
  22 #include "engine_fwd.h"
  23
  24 #include <QSet>
  25
  26 class EngineSubject;
  27 class MetaBundle;
  28 class QString;
  29
  30 /**
  31  * if you want to observe the engine, inherit from this class and attach yourself to
  32  * the engine with attach
  33  * Note that all positional information and times are in milliseconds
  34  */
  35 class AMAROK_EXPORT EngineObserver
  36 {
  37 public:
  38     EngineObserver();
  39     EngineObserver( EngineSubject* );
  40     virtual ~EngineObserver();
  41     virtual void engineStateChanged( Engine::State currentState, Engine::State oldState = Engine::Empty );
  42     virtual void engineTrackEnded( int finalPosition, int trackLength, const QString &reason );
  43     virtual void engineNewTrackPlaying();
  44     virtual void engineNewMetaData( const QHash<qint64, QString> &newMetaData, bool trackChanged );
  45     virtual void engineVolumeChanged( int percent );
  46     virtual void engineTrackPositionChanged( long position , bool userSeek );
  47     virtual void engineTrackLengthChanged( long seconds );
  48
  49 private:
  50     EngineSubject *m_subject;
  51 };
  52
  53 /**
  54  * Inherited by EngineController.
  55  * Notify observer functionality is captured in this class.
  56  */
  57 class EngineSubject
  58 {
  59 public:
  60     void AMAROK_EXPORT attach( EngineObserver *observer );
  61     void AMAROK_EXPORT detach( EngineObserver *observer );
  62
  63 protected:
  64     EngineSubject();
  65     virtual ~EngineSubject();
  66     void stateChangedNotify( Engine::State /*state*/ );
  67     void trackEnded( int /*finalPosition*/, int /*trackLength*/, const QString &reason );
  68     void newMetaDataNotify( const QHash<qint64, QString> &newMetaData, bool trackChanged ) const;
  69     void volumeChangedNotify( int /*percent*/ );
  70     /* userSeek means the position didn't change due to normal playback */
  71     void trackPositionChangedNotify( long /*position*/ , bool userSeek=false );
  72     void trackLengthChangedNotify( long /*seconds*/ );
  73     void newTrackPlaying() const;
  74
  75 private:
  76     QSet<EngineObserver*> Observers;
  77     Engine::State m_oldEngineState;
  78 };
  79
  80 #endif // AMAROK_ENGINEOBSERVER_H