Added Equalizer support on AudioEngine class

Two public methods added :
 * int equalizerBandCount()
 * bool setEqualizerBand(int band, int value)
One private method :
 * void initEqualizer()

Settings and GUI must be made in an external plugin

src/libtomahawk/audio/AudioEngine.cpp

@@ -182,6 +182,7 @@ AudioEngine::AudioEngine()
     d->waitingOnNewTrack = false;
     d->state = Stopped;
     d->coverTempFile = 0;
+    d->audioEffect = 0;
 
     d->s_instance = this;
     tDebug() << "Init AudioEngine";
@@ -191,7 +192,7 @@ AudioEngine::AudioEngine()
 
     d->mediaObject = new Phonon::MediaObject( this );
     d->audioOutput = new Phonon::AudioOutput( Phonon::MusicCategory, this );
-    Phonon::createPath( d->mediaObject, d->audioOutput );
+    d->audioPath = Phonon::createPath( d->mediaObject, d->audioOutput );
 
     d->mediaObject->setTickInterval( 150 );
     connect( d->mediaObject, SIGNAL( stateChanged( Phonon::State, Phonon::State ) ), d_func(), SLOT( onStateChanged( Phonon::State, Phonon::State ) ) );
@@ -207,6 +208,8 @@ AudioEngine::AudioEngine()
     onVolumeChanged( d->audioOutput->volume() );
 
     setVolume( TomahawkSettings::instance()->volume() );
+
+    initEqualizer();
 }
 
 
@@ -1231,3 +1234,55 @@ AudioEngine::setCurrentTrackPlaylist( const playlistinterface_ptr& playlist )
         emit currentTrackPlaylistChanged( d->currentTrackPlaylist );
     }
 }
+
+
+void
+AudioEngine::initEqualizer()
+{
+    Q_D( AudioEngine );
+
+    QList< Phonon::EffectDescription > effectDescriptions = Phonon::BackendCapabilities::availableAudioEffects();
+    foreach ( Phonon::EffectDescription effectDesc, effectDescriptions )
+    {
+        if ( effectDesc.name().toLower().contains( "eq" ) )
+        {
+            d->audioEffect = new Phonon::Effect( effectDesc );
+            d->audioPath.insertEffect( d->audioEffect );
+            break;
+        }
+    }
+}
+
+
+int
+AudioEngine::equalizerBandCount()
+{
+    Q_D( AudioEngine );
+
+    if ( d->audioEffect )
+    {
+        QList< Phonon::EffectParameter > params = d->audioEffect->parameters();
+        return params.size();
+    }
+
+    return 0;
+}
+
+
+bool
+AudioEngine::setEqualizerBand( int band, int value )
+{
+    Q_D( AudioEngine );
+
+    if ( d->audioEffect )
+    {
+        QList< Phonon::EffectParameter > params = d->audioEffect->parameters();
+        if ( band < params.size() )
+        {
+            d->audioEffect->setParameterValue( params.at( band ), value );
+            return true;
+        }
+    }
+
+    return false;
+}

src/libtomahawk/audio/AudioEngine.h

@@ -62,6 +62,9 @@ public:
     qint64 currentTime() const;
     qint64 currentTrackTotalTime() const;
 
+    int equalizerBandCount();
+    bool setEqualizerBand( int band, int value );
+
 public slots:
     void playPause();
     void play();
@@ -145,6 +148,7 @@ private:
     void queueState( AudioState state );
     void setState( AudioState state );
     void setCurrentTrackPlaylist( const Tomahawk::playlistinterface_ptr& playlist );
+    void initEqualizer();
 
     Q_DECLARE_PRIVATE( AudioEngine );
     AudioEnginePrivate* d_ptr;

src/libtomahawk/audio/AudioEngine_p.h

@@ -1,7 +1,10 @@
 
 #include <phonon/MediaObject>
 #include <phonon/AudioOutput>
+#include <phonon/Path>
 #include <phonon/BackendCapabilities>
+#include <phonon/Effect>
+#include <phonon/EffectParameter>
 
 #include <stdint.h>
 
@@ -37,6 +40,8 @@ private:
 
     Phonon::MediaObject* mediaObject;
     Phonon::AudioOutput* audioOutput;
+    Phonon::Path audioPath;
+    Phonon::Effect* audioEffect;
 
     unsigned int timeElapsed;
     bool expectStop;