import javax.sound.midi.*;
import java.io.*;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;


public class MiniMusicService implements Service {

    
    MyDrawPanel myPanel;


   public JPanel getGuiPanel() {
       
       JPanel mainPanel = new JPanel();
       myPanel = new MyDrawPanel();
       JButton playItButton = new JButton("Play it");
       playItButton.addActionListener(new PlayItListener());
       mainPanel.add(myPanel);
       mainPanel.add(playItButton);
       return mainPanel;
   }


    public class PlayItListener implements ActionListener {
      public void actionPerformed(ActionEvent ev) {

       try {

         // make (and open) a sequencer, make a sequence and track

         Sequencer sequencer = MidiSystem.getSequencer();         
         sequencer.open();
        
         sequencer.addControllerEventListener(myPanel, new int[] {127});
         Sequence seq = new Sequence(Sequence.PPQ, 4);
         Track track = seq.createTrack();     

         // now make two midi events (containing a midi message)

      

      for (int i = 0; i < 100; i+= 4) {

        int  rNum = (int) ((Math.random() * 50) + 1);
         if (rNum < 38) {  // so now only do it if num <38 (75% of the time)
         
           track.add(makeEvent(144,1,rNum,100,i));
        
           track.add(makeEvent(176,1,127,0,i));
         
           track.add(makeEvent(128,1,rNum,100,i + 2));
         }
       } // end loop
        
          // add the events to the track            
          // add the sequence to the sequencer, set timing, and start

          sequencer.setSequence(seq);

          sequencer.start();
          sequencer.setTempoInBPM(220);
      } catch (Exception ex) {ex.printStackTrace();}

    } // close actionperformed
   } // close inner class


   public MidiEvent makeEvent(int comd, int chan, int one, int two, int tick) {
          MidiEvent event = null;
          try {
            ShortMessage a = new ShortMessage();
            a.setMessage(comd, chan, one, two);
            event = new MidiEvent(a, tick);
            
          }catch(Exception e) { }
          return event;
       }



 class MyDrawPanel extends JPanel implements ControllerEventListener {
      
      // only if we got an event do we want to paint
      boolean msg = false;

      public void controlChange(ShortMessage event) {
         msg = true;       
         repaint();         
      }

     public Dimension getPreferredSize() {
        return new Dimension(300,300);
     }

      public void paintComponent(Graphics g) {
       if (msg) {
            
         Graphics2D g2 = (Graphics2D) g;

         int r = (int) (Math.random() * 250);
         int gr = (int) (Math.random() * 250);
         int b = (int) (Math.random() * 250);

         g.setColor(new Color(r,gr,b));

         int ht = (int) ((Math.random() * 120) + 10);
         int width = (int) ((Math.random() * 120) + 10);

         int x = (int) ((Math.random() * 40) + 10);
         int y =  (int) ((Math.random() * 40) + 10);        
         
         g.fillRect(x,y,ht, width);
         msg = false;

       } // close if
     } // close method
   }  // close inner class

} // close class