// Fig. 22.10: MidiDemo.java // Simulates a musical keyboard with various // instruments to play, also featuring recording, MIDI file // playback and simulating MIDI playback with the keyboard // Java core packages import java.awt.*; import java.awt.event.*; import java.io.*; // Java extension packages import javax.swing.*; import javax.swing.event.*; import javax.sound.midi.*; public class MidiDemo extends JFrame { // recording MIDI data private MidiRecord midiRecord; // synthesize MIDI functioning private MidiSynthesizer midiSynthesizer; // MIDI data in MIDI file private MidiData midiData; // timer for simulating MIDI on piano private Timer pianoTimer; // piano keys private JButton noteButton[]; // volume, tempo sliders private JSlider volumeSlider, resolutionSlider; // containers and panels holding GUI private Container container; private JPanel controlPanel, buttonPanel; // instrument selector and buttons GUI private JComboBox instrumentBox; private JButton playButton, recordButton, saveButton, pianoPlayerButton, listenButton; // tempo, last piano key invoked, volume of MIDI private int resolution, lastKeyOn = -1, midiVolume = 40; // boolean value indicating if program is in recording mode private boolean recording = false; // first note number of first piano key, max number of keys private static int FIRST_NOTE = 32, MAX_KEYS = 64; // constructor for MidiDemo public MidiDemo() { super( "MIDI Demo" ); container = getContentPane(); container.setLayout( new BorderLayout() ); // synthesizer must be instantiated to enable synthesis midiSynthesizer = new MidiSynthesizer(); // make piano keys makeKeys(); // add control panel to frame controlPanel = new JPanel( new BorderLayout() ); container.add( controlPanel, BorderLayout.NORTH ); makeConfigureControls(); // add button panel to frame buttonPanel = new JPanel( new GridLayout( 5, 1 ) ); controlPanel.add( buttonPanel, BorderLayout.EAST ); // make GUI makePlaySaveButtons(); makeRecordButton(); makePianoPlayerButton(); } // end constructor // utility method making piano keys private void makeKeys() { // panel containing keys JPanel keyPanel = new JPanel( null ); container.add( keyPanel, BorderLayout.CENTER ); // piano keys noteButton = new JButton[ MAX_KEYS ]; // add MAX_KEYS buttons and what note they sound for ( int i = 0; i < MAX_KEYS; i++ ) { final int note = i; noteButton[ i ] = new JButton(); // setting white keys noteButton[ i ].setBackground( Color.white ); // set correct spacing for buttons noteButton[ i ].setBounds( ( i * 11 ), 1, 11, 40 ); keyPanel.add( noteButton[ i ] ); // register a mouse listener for mouse events noteButton[ i ].addMouseListener( // anonymous inner class to handle mouse events new MouseAdapter() { // invoke key note when mouse touches key public void mouseEntered( MouseEvent mouseEvent ) { // if recording, send message to receiver if ( recording ) midiSynthesizer.sendMessage( ShortMessage.NOTE_ON, note + FIRST_NOTE, midiVolume ); // else just sound the note else midiSynthesizer.midiNoteOn( note + FIRST_NOTE, midiVolume ); // turn key color to blue noteButton[ note ].setBackground( Color.blue ); } // turn key note off when mouse leaves key public void mouseExited( MouseEvent mouseEvent ) { if ( recording ) midiSynthesizer.sendMessage( ShortMessage.NOTE_OFF, note + FIRST_NOTE, midiVolume ); else midiSynthesizer.midiNoteOff( note + FIRST_NOTE ); noteButton[ note ].setBackground( Color.white ); } } // end MouseAdapter ); // end call to addMouseListener } // end for loop } // end method makeKeys // set up configuration controls private void makeConfigureControls() { JPanel configurePanel = new JPanel( new GridLayout( 5, 1 ) ); controlPanel.add( configurePanel, BorderLayout.WEST ); instrumentBox = new JComboBox( midiSynthesizer.getInstruments() ); configurePanel.add( instrumentBox ); // register an ActionListener for instrumentBox events instrumentBox.addActionListener( // anonymous inner class to handle instrument selector new ActionListener() { // change current instrument program public void actionPerformed( ActionEvent event ) { // change instrument in synthesizer midiSynthesizer.changeInstrument( instrumentBox.getSelectedIndex() ); } } // end ActionListener ); // end call to method addActionListener JLabel volumeLabel = new JLabel( "volume" ); configurePanel.add( volumeLabel ); volumeSlider = new JSlider( SwingConstants.HORIZONTAL, 5, 80, 30 ); // register a ChangeListener for slider change events volumeSlider.addChangeListener( // anonymous inner class to handle volume slider events new ChangeListener() { // change volume public void stateChanged( ChangeEvent changeEvent ) { midiVolume = volumeSlider.getValue(); } } // end class ChangeListener ); // end call to method addChangeListener configurePanel.add( volumeSlider ); JLabel tempLabel = new JLabel( "tempo" ); configurePanel.add( tempLabel ); resolutionSlider = new JSlider( SwingConstants.HORIZONTAL, 1, 10, 1 ); // register a ChangeListener slider for change events resolutionSlider.addChangeListener( // anonymous inner class to handle tempo slider events new ChangeListener() { // change resolution if value changed public void stateChanged( ChangeEvent changeEvent ) { resolution = resolutionSlider.getValue(); } } // end ChangeListener ); // end call to method addChangeListener resolutionSlider.setEnabled( false ); configurePanel.add( resolutionSlider ); } // end method makeConfigureControls // set up play and save buttons private void makePlaySaveButtons() { playButton = new JButton( "Playback" ); // register an ActionListener for playButton events playButton.addActionListener( // anonymous inner class to handle playButton event new ActionListener() { // playback last recorded MIDI public void actionPerformed( ActionEvent event ) { if ( midiRecord != null ) midiRecord.play(); } } // end ActionListener ); // end call to method addActionListener buttonPanel.add( playButton ); playButton.setEnabled( false ); listenButton = new JButton( "Play MIDI" ); // register an ActionListener for listenButton events listenButton.addActionListener( // anonymous inner class to handle listenButton events new ActionListener() { // playback MIDI file public void actionPerformed( ActionEvent event ) { File midiFile = getFile(); if ( midiFile == null ) return; midiData = new MidiData(); // prepare MIDI track if ( midiData.initialize( midiFile ) == false ) return; // play MIDI data midiData.play(); } } // end ActionListener ); // end call to method addActionListener buttonPanel.add( listenButton ); saveButton = new JButton( "Save MIDI" ); // register an ActionListener for saveButton events saveButton.addActionListener( // anonymous inner class to handle saveButton events new ActionListener() { // get save file and save recorded MIDI public void actionPerformed( ActionEvent event ) { File saveFile = getSaveFile(); if ( saveFile != null ) midiRecord.saveSequence( saveFile ); } } // end ActionListener ); // end call to method addActionListener buttonPanel.add( saveButton ); saveButton.setEnabled( false ); } // end method makePlaySaveButtons // make recording button private void makeRecordButton() { recordButton = new JButton( "Record" ); // register an ActionListener for recordButton events recordButton.addActionListener( // anonymous inner class to handle recordButton events new ActionListener() { // start or stop recording public void actionPerformed( ActionEvent event ) { // record MIDI when button is "record" button if ( recordButton.getText().equals("Record") ) { if ( midiRecord == null ) { // create new instance of recorder // by passing in synthesizer transmitter midiRecord = new MidiRecord( midiSynthesizer.getTransmitter() ); if ( midiRecord.initialize() == false ) return; } else midiRecord.makeTrack(); midiRecord.startRecord(); // disable playback during recording playButton.setEnabled( false ); // change recording button to stop recordButton.setText( "Stop" ); recording = true; } // end if // stop recording when button is "stop" button else { midiRecord.stopRecord(); recordButton.setText( "Record" ); recording = false; playButton.setEnabled( true ); saveButton.setEnabled( true ); } } // end method actionPerformed } // end ActionListener ); // end call to method addActionListener buttonPanel.add( recordButton ); } // end method makeRecordButton // create Piano Player button and functionality private void makePianoPlayerButton() { pianoPlayerButton = new JButton( "Piano Player" ); // register an ActionListener for pianoPlayerButton events pianoPlayerButton.addActionListener( // anonymous inner class to handle pianoPlayerButton new ActionListener() { // initialize MIDI data and piano player timer public void actionPerformed( ActionEvent event ) { File midiFile = getFile(); if ( midiFile == null ) return; midiData = new MidiData(); // prepare MIDI track if ( midiData.initialize( midiFile ) == false ) return; if ( midiData.initializeTrack() == false ) return; // set initial resolution from MIDI resolution = midiData.getResolution(); // new instance of timer for handling // piano sounds and key pressing with tempo pianoTimer = new Timer( midiData.getEventDelay() * resolution, new TimerHandler() ); listenButton.setEnabled( false ); pianoPlayerButton.setEnabled( false ); resolutionSlider.setEnabled( true ); pianoTimer.start(); } // method end actionPerformed } // end ActionListener ); // end call to method addActionListener buttonPanel.add( pianoPlayerButton ); } // end method makePianoPlayerButton // inner class handles MIDI timed events private class TimerHandler implements ActionListener { // simulate key note of event if present, jump to next // event in track and set next delay interval of timer // method invoked when timer reaches next event time public void actionPerformed( ActionEvent actionEvent ) { // if valid last key on, set it white if ( lastKeyOn != -1 ) noteButton[ lastKeyOn ].setBackground( Color.white ); noteAction(); midiData.goNextEvent(); // stop piano player when end of MIDI track if ( midiData.isTrackEnd() == true ) { if ( lastKeyOn != -1 ) noteButton[ lastKeyOn ].setBackground( Color.white ); pianoTimer.stop(); listenButton.setEnabled( true ); pianoPlayerButton.setEnabled( true ); resolutionSlider.setEnabled( false ); return; } // end if isTrackEnd // set interval before next sounding event pianoTimer.setDelay( midiData.getEventDelay() * resolution ); } // end actionPerformed method } // end inner class TimerHandler // determine which note to sound // according to MIDI messages private void noteAction() { // during Note On message, sound note and press key if ( midiData.getEventCommand() == ShortMessage.NOTE_ON ) { // make sure valid note is in range of keys if ( ( midiData.getNote() >= FIRST_NOTE ) && ( midiData.getNote() < FIRST_NOTE + MAX_KEYS ) ) { lastKeyOn = midiData.getNote() - FIRST_NOTE; // set key color to red noteButton[ lastKeyOn ].setBackground( Color.red ); // send and sound note through synthesizer midiSynthesizer.sendMessage( 144, midiData.getNote(), midiData.getVolume() ); } // end if // else no last key pressed else lastKeyOn = -1; } // end if // receiving Note Off message will sound off note // and change key color back to white else // if message command is note off if ( midiData.getEventCommand() == ShortMessage.NOTE_OFF ) { if ( ( midiData.getNote() >= FIRST_NOTE ) && ( midiData.getNote() < FIRST_NOTE + MAX_KEYS ) ) { // set appropriate key to white noteButton[ midiData.getNote() - FIRST_NOTE ].setBackground( Color.white ); // send note off message to receiver midiSynthesizer.sendMessage( 128, midiData.getNote(), midiData.getVolume() ); } } // end if } // end method noteAction // get save file from computer public File getSaveFile() { JFileChooser fileChooser = new JFileChooser(); fileChooser.setFileSelectionMode( JFileChooser.FILES_ONLY ); int result = fileChooser.showSaveDialog( this ); if ( result == JFileChooser.CANCEL_OPTION ) return null; else return fileChooser.getSelectedFile(); } // get file from computer public File getFile() { JFileChooser fileChooser = new JFileChooser(); fileChooser.setFileSelectionMode( JFileChooser.FILES_ONLY ); int result = fileChooser.showOpenDialog( this ); if ( result == JFileChooser.CANCEL_OPTION ) return null; else return fileChooser.getSelectedFile(); } // execute application public static void main( String[] args ) { MidiDemo midiTest = new MidiDemo(); midiTest.setSize( 711, 225 ); midiTest.setDefaultCloseOperation ( EXIT_ON_CLOSE ); midiTest.setVisible( true ); } } // end class MidiDemo