Java Tips - How to work with Canvas in mobile application

This Java tips explains how to work with Canvas in mobile applications. The Canvas class is a base class for writing applications that need to handle low-level events and to issue graphics calls for drawing to the mobile display. Game applications will likely make heavy use of the Canvas class.


import javax.microedition.midlet.*;

import javax.microedition.lcdui.*;



public class CanvasDemo extends MIDlet {

    

    private boolean boolMotion=false;    

    private int iX=10,iY=60;    

    

    Display mDisplay;

    Thread th;

    

    public void destroyApp(boolean unconditional){}

    

    public void pauseApp() {}

    

    public void startApp() {

        mDisplay = Display.getDisplay(this);

        final MyCanvas can = new MyCanvas();

        mDisplay.setCurrent(can);

    }

    

}



import javax.microedition.midlet.*;

import javax.microedition.lcdui.*;



public class MyCanvas extends Canvas implements Runnable {

    int count;

    public MyCanvas() {

        Thread th=new Thread(this);

        th.start();

    }

    

    //Drawing on canvas

    public void paint(Graphics g) {

        g.setColor(122,122,122);

        g.fillRect(100,30,40,40);

        g.drawString("counter="+count,0,80,g.TOP|g.LEFT);

    }

    

    //Handling keyEvents

    protected void keyPressed(int keyCode) {

        repaint();

    }

    

    public void run() {

        while(true) {

            count++;

            try {

                Thread.sleep(1000);

            }catch(Exception e){}

            repaint();

            count%=1000;

        }        

    }    

}

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