import javax.microedition.lcdui.Canvas;
import javax.microedition.lcdui.Font;
import javax.microedition.lcdui.Graphics;
 
/**
 * Canvas demostrates key handling procedure example.
 */
public class MyCanvas extends Canvas {
    /**
     * Array holds string displayed with key code and key name.
     */
    private String[] displayStrings;
    /**
     * Holds last pressed key code.
     */
    private int pressedKey;
 
    /**
     *
     */
    public MyCanvas() {
        pressedKey = 0;
        displayStrings = new String[2];
        displayStrings[0] = "Key code: ";
        displayStrings[1] = "Key: ";
    }
    /**
     * From Canvas.
     * Method fills canvas draw area with grey color, draws a rectangle border
     * for a canvas and displays last presend key code and it's name.
     * @param g
     */
    protected void paint( Graphics g ) {
        // Setting up text font to default one.
        g.setFont( Font.getDefaultFont() );
        // Setting up Grey color as the current one.
        g.setColor( 0xC0C0C0 );
        // Filling the screen with the current color.
        g.fillRect( 0, 0, getWidth(), getHeight() );
        // Setting text and canvas border color.
        g.setColor( 0x000000 );
        // Draw a simple border for our canvas.
        g.drawRect( 0 + 2, 0 + 2, getWidth() - 4, getHeight() - 4 );
        // Changing pen position to where our key codes will be displayed
        g.translate( 4, getHeight() / 2 );
        // drawing a key code
        // If pressedKey variable holds '0' as a value no key code ot it's name
        // will be displayed then.
        if( pressedKey != 0) {
           // Drawing a string containing pressed key code
           g.drawString( displayStrings[0] + pressedKey,
                   0, 0, Graphics.TOP | Graphics.LEFT );
           // Drawing a string containing pressed key code name
           g.drawString( displayStrings[1] +
                   "'" + getKeyName( pressedKey ) + "'",
                   0, 20, Graphics.TOP | Graphics.LEFT );
        } else {
           g.drawString( "Press a key ... ", 0, 20, Graphics.TOP | Graphics.LEFT );
        }
        // moving cursor back to where it was
        g.translate( 0, - getHeight() / 2 );
    }
    /**
     * From Canvas.
     * Method saves code of a pressed key to the pressedKey variable.
     * @param keyCode
     */
    protected void keyPressed( int keyCode ) {
        pressedKey = keyCode;
        repaint();
    }
}

    /**
     * Reference to our Canvas implementation object.
     */
    private MyCanvas canvas;
 
    public ReceivingKeyEvents() {
        display = Display.getDisplay( this );
        setupMainForm();
        setupCanvas();
    }
    /**
     * Instantiates a canvas variable with MyCanvas instance.
     */
    private void setupCanvas() {
        canvas = new MyCanvas();
        // Adding 'Back' softkey to be able to return to app's main form.
        canvas.addCommand( BACK_COMMAND );
        // Setting up our MIDlet class as canvas command listener.
        canvas.setCommandListener( this );
    }
    /**
     * From CommandListener.
     * Called by the system to indicate that a command has been invoked on a
     * particular displayable.
     * @param command the command that was invoked
     * @param displayable the displayable where the command was invoked
     */
    public void commandAction(Command command, Displayable displayable) {
        if (command == EXIT_COMMAND) {
            // Exit the MIDlet
            exit();
        } else if (command == EXECUTE_COMMAND) {
            // Bringing canvas to the foreground.
            display.setCurrent( canvas );
        } else if ( command == BACK_COMMAND ) {
            // Switching back from canvas to mainForm.
            display.setCurrent( mainForm );
        }
    }