sabato 21 giugno 2014

Implementing UI callbacks with audio player functionality

In the latest posts we discussed how to create the User Interface of our application and how to wrap all the player audio functionality into one simple AudioPlayer class. Now we are gonna put the two things together, the finishing result should be something that slightly works.

This is the uiBehaviour() procedure we left behind (MainView class).

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 private void uiBehaviour()
 {
  //File chooser
  fc.setMultiSelectionEnabled(true);
  fc.setFileFilter(new FileFilter() {
   
   @Override
   public String getDescription() {
    return "only supported audio files (mp3, wav)";
   }
   
   @Override
   public boolean accept(File f) {
    if(f.isDirectory())
     return true;
    if(f.getName().endsWith(".mp3"))
     return true;
    if(f.getName().endsWith(".wav"))
     return true;
    return false;
   }
  });
  btnAdd.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent e) {
    int returnVal = fc.showOpenDialog(btnAdd);
    if(returnVal == JFileChooser.APPROVE_OPTION){
     File[] files = fc.getSelectedFiles();
     for(File f : files){
      player.addSong(f.getAbsolutePath());
      songList.addElement(f.getName());
      log("Added file " + f.getName() + " to playlist");
     }
    }
    else{
     log("No file selected");
    }
   }
  });
  //Song List
  jSongList.setModel(songList);
  jSongList.setSelectionMode(ListSelectionModel.MULTIPLE_INTERVAL_SELECTION);
  jSongList.setLayoutOrientation(JList.VERTICAL);
  //Event that triggers at double click
  jSongList.addMouseListener(new MouseAdapter()
  {
   public void mouseClicked(MouseEvent evt){
    JList list = (JList)evt.getSource();
    if(evt.getClickCount() == 2){
     log("Double click detected, moving to selected item.");
     int index = list.locationToIndex(evt.getPoint());
     player.setIndexSong(index);
     try {
      player.play();
     } catch (BasicPlayerException ev) {
      ev.printStackTrace();
     }
    }
   }
  });
  
  //Btn Delete
  btnDel.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent e) {
    //Executed Outside UI Thread
    BackgroundExecutor.get().execute(new Runnable() {
     
     @Override
     public void run() {
      int[] indexes = jSongList.getSelectedIndices();
      int removed = 0;
      for(int i : indexes)
      {
       log("Removed Song ("+(i-removed)+")" + songList.get(i-removed));
       player.removeSong(i-removed);
       songList.remove(i-removed);
       removed++;
      }
     }
    });
   }
  });
  //Play Btn
  btnPlay.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent e) {
    try {
     tooglePlay();
    } catch (BasicPlayerException e1) {
     e1.printStackTrace();
    }
   }
  });
  //Next and Previous btns
  btnNext.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent arg0) {
    try {
     player.nextSong();
     //seekbar.resetLastSeek();
    } catch (BasicPlayerException e) {
     log("Error calling the next song");
     e.printStackTrace();
    }
   }
  });
  
  btnPrev.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent arg0) {
    try {
     player.prvSong();
     //seekbar.resetLastSeek();
    } catch (BasicPlayerException e) {
     log("Error calling the previous song");
     e.printStackTrace();
    }
   }
  });
  //Player related behaviour
  player.addBasicPlayerListener(new BasicPlayerListener() {
   
   @Override
   public void stateUpdated(BasicPlayerEvent event) {
    if(event.getCode() == BasicPlayerEvent.EOM)
    {
     //seekbar.resetLastSeek();
     try {
      player.nextSong();
     } catch (BasicPlayerException e) {
      e.printStackTrace();
     }
     log("EOM event catched, calling next song.");
    }
    if(event.getCode() == BasicPlayerEvent.PAUSED){
     //btnPlay.setText(">");
     btnPlay.setIcon(playIcon);
    }
    if(event.getCode() == BasicPlayerEvent.RESUMED){
     //btnPlay.setText("||");
     btnPlay.setIcon(pauseIcon);
    }
   }
   
   @Override
   public void setController(BasicController arg0) {}
   
   @Override
   public void progress(int bytesread, long microseconds, byte[] pcmdata, Map properties) {
    //we don't want to use microseconds directly because it gets resetted on seeking
    seekbar.updateSeekBar(player.getProgressMicroseconds(), currentAudioDurationSec);
    if(wff != null)
     wff.updateWave(pcmdata);
    if(fdf != null)
     fdf.updateWave(pcmdata);
   }
   
   @Override
   public void opened(Object arg0, Map arg1) {
    //btnPlay.setText("||");
    btnPlay.setIcon(pauseIcon);
    jSongList.setSelectedIndex(player.getIndexSong());
    lblplaying.setText("Now Playing: " + songList.get(player.getIndexSong()));
    currentAudioDurationSec = player.getAudioDurationSeconds();
   }
  });
  
  //Timers Executor / Every 1 Second
  timersExec.scheduleAtFixedRate(new Runnable() {
   
   @Override
   public void run() {
    updateTimers();
    //updatePlayingText();
   }
  }, 0, 1, TimeUnit.SECONDS);
  
  
  titleExec.scheduleAtFixedRate(new Runnable() {
   
   @Override
   public void run() {
    updatePlayingText();
   }
  }, 0, 1, TimeUnit.SECONDS);
  
  //Btn Waveform
  btnShWf.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent arg0) {
    SwingUtilities.invokeLater(new Runnable(){
     @Override
     public void run()
     {
      wff = new WaveformFrame();
      wff.setVisible(true);
     }
    });
   }
  });
  //Btn that show freq diagram
  btnShDi.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent arg0) {
    fdf = new FreqDiagFrame();
    fdf.setVisible(true);
   }
  });
  //Open status window frame
  btnShSt.addActionListener(new ActionListener() {
   
   @Override
   public void actionPerformed(ActionEvent arg0) {
    //stf = new StatusFrame();
    stf.setVisible(true);
   }
  });
  
 }
 
 /**
  * Used by the Play/Pause button
  */
 private void tooglePlay() throws BasicPlayerException
 {
  if(songList.size() == 0)
   return;
  if(!player.isPaused()){
   player.pause();
   //btnPlay.setText(">");
   btnPlay.setIcon(playIcon);
   }
  else{player.play();}
 }

It's a lot of code so let's analyze it in order:

  • File chooser: It's a swing component that can be used to create an interface to select one or multiple files. I've set a file filter to let it see only files ending with .mp3 or .wav.
  • btnAdd will use the File chooser to get the songs the user selected, adding it to the playlist.
  • Song list: contains visual list of the playlist, I've added a behavior so that when a double click occurs it gets the index clicked and plays the selected song.
  • Btn Delete: delete the selected songs from the playlist
  • Play Btn: a simple play/pause toogle button.
  • Btn Next/ Btn Prev: move to next or previous song.
  • Player related behaviour: this is where all the fun things happens. We add a new event listener to the basic player, this way we can have some things done every time a certain event happens regarding the player.
    • We use progress to update the seekbar
    • We use opened to detect if a new song start playing ( a new audio file has been opened by the BasicPlayer class...)
    • With state update we detect if the streaming has been paused, stopped, resumed, etc.
  • Other: something regarding additional features

There are some concept that we already explained in the previous posts, the code shouldn't be that hard but for problems or anything just let me know in the comments.