fix previous button, single point of definition

LenaPi/controllers/MusicPlayer.h

@@ -6,7 +6,10 @@
 #include <models/NavigationItemModel.h>
 
 /**
- * @brief MusicPlayer providing interface to QML and Navigation
+ * @brief MusicPlayer providing interface to QML and Navigation.
+ *
+ * Adds media from directory referenced by the current navigation item to
+ * playlist and provides interface to QML MusicPlayer.
  */
 class MusicPlayer : public QMediaPlayer
 {
@@ -17,9 +20,9 @@ class MusicPlayer : public QMediaPlayer
     Q_PROPERTY(bool pHasPrevious READ hasPrevious NOTIFY hasPreviousChanged)
     Q_PROPERTY(bool pIsPlaying READ isPlaying NOTIFY isPlayingChanged)
     Q_PROPERTY(double pProgress READ getProgress NOTIFY progressChanged)
-    Q_PROPERTY(QString pMediaLength READ getMediaLength NOTIFY mediaLengthChanged)
-    Q_PROPERTY(QString pTime READ getTime NOTIFY progressChanged)
-    Q_PROPERTY(QString pMediaTitle READ getMediaTitle NOTIFY mediaTitleChanged)
+    Q_PROPERTY(QString pMediaLength READ getMediaDuration NOTIFY mediaLengthChanged)
+    Q_PROPERTY(QString pTime READ getPosition NOTIFY progressChanged)
+    Q_PROPERTY(QString pMediaTitle READ getMediaTitle NOTIFY metaDataChanged)
 
 signals:
     void navigateTo(NavigationItemModel *item);
@@ -29,12 +32,16 @@ signals:
     void isPlayingChanged();
     void progressChanged();
     void mediaLengthChanged();
-    void mediaTitleChanged();
 
 public:
     MusicPlayer(QObject *parent = Q_NULLPTR);
     ~MusicPlayer() =default;
 
+    /**
+     * @brief Init playlist with media from directory referenced by item.
+     * @param item Navigation item representing a leaf
+     * @see void readMedia(const QString& path)
+     */
     void init(NavigationItemModel* item);
 
     /**
@@ -42,23 +49,71 @@ public:
      * @return Path to media cover image.
      */
     inline const QString& getCoverImageSource() const {return mCurrentItem->getImageSource();}
-
-
+    /**
+     * @brief Indicates whether the media player is currently playing a track.
+     * @return true if media player is playing a track.
+     */
     bool isPlaying() const;
+    /**
+     * @brief Indicates whether there is a next item in the playlist.
+     * @return True if there is a next item in the playlist
+     * Does not wrap.
+     */
     bool hasNext() const;
+    /**
+     * @brief Indicates whether there is a previous item in the playlist.
+     * @return True if there is a previous item in the playlist
+     * Does not wrap.
+     */
     bool hasPrevious() const;
 
+    /**
+     * @brief Get media progress as value in between 0 and 1
+     * @return Media progress
+     * 0 corresponds to the beginning and 1 to the end of the current track.
+     */
     double getProgress() const;
 
+    /**
+     * @brief Get current media title extracted from media meta data (id3 tags)
+     * @return Current media title
+     */
     QString getMediaTitle() const;
-    QString getMediaLength();
-    QString getTime();
+    /**
+     * @brief Get duration of the current track
+     * @return Duration of the current track formatted as string
+     * @see QMediaPlayer::duration()
+     * @see millisecondsToString(int timeInMilliseconds) const
+     */
+    QString getMediaDuration() const;
+    /**
+     * @brief Get current position within the track
+     * @return Postion within the track formatted as string
+     * @see QMediaPlayer::position()
+     * @see millisecondsToString(int timeInMilliseconds) const
+     */
+    QString getPosition() const;
 
 public slots:
+    /**
+     * @brief Navigate back to navgation list
+     */
     void navigateBack();
+    /**
+     * @brief Play or pause music depending on whether it is currently playing
+     */
     void playPause();
+    /**
+     * @brief Stop music and reset track to first track in playlist
+     */
     void stopMusic();
+    /**
+     * @brief Play next track in current playlist if available
+     */
     void playNext();
+    /**
+     * @brief Replay previoustrack in current playlist if available
+     */
     void playPrevious();
 
 private:
@@ -66,20 +121,22 @@ private:
      * @brief Resets playlist to first track if playlist exists and is non-empty
      */
     void resetPlaylistToFirstTrack();
+    /**
+     * @brief Clear the current playlist
+     */
     void clearPlaylist();
+    /**
+     * @brief Add all media from path to playlist
+     * @param path Path to media
+     */
     void readMedia(const QString& path);
     /**
-     * @brief Transforms time in milliseconds into a string
+     * @brief Format time in milliseconds acoording to [M]m:ss
      * @param time Time in ms
-     * @return
-     * @todo use QDateTime
+     * @return formateted string
      */
-    QString timeToString(int time);
+    QString millisecondsToString(int timeInMilliseconds) const;
 
-    int mCurrentMediaItemLength = 0;
-    int mCurrentTime = 0;
-    double mCurrentMediaItemProgress = 0;
-    QString mMediaTitle = QString("");
     NavigationItemModel* mCurrentItem = nullptr;
 };