DoubleBufferedImage.java Source code

Introduction

Here is the source code for DoubleBufferedImage.java

Source

import java.awt.Color;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.net.MalformedURLException;
import java.net.URL;

import javax.swing.JApplet;
import javax.swing.JFrame;

public class DoubleBufferedImage extends JApplet {
    private Image dbImage;

    private Image originalImage;

    private int xLocation = 0;

    private int imageWidth, imageHeight;

    private Graphics dbImageGraphics;

    private String imageURLString = "file:/peppers.png";

    public void init() {
        URL url = null;
        try {
            url = new URL(imageURLString);
        } catch (MalformedURLException me) {
            showStatus("Malformed URL: " + me.getMessage());
        }

        originalImage = getImage(url);

        MediaTracker mt = new MediaTracker(this);
        mt.addImage(originalImage, 0);
        try {
            mt.waitForID(0);
        } catch (InterruptedException ie) {
        }

        imageWidth = originalImage.getWidth(null);
        imageHeight = originalImage.getHeight(null);

        dbImage = this.createImage(imageWidth, imageHeight);
        dbImageGraphics = dbImage.getGraphics();
    }

    public void update(Graphics g) {
        paint(g);
    }

    public void paint(Graphics g) {
        if (xLocation == imageWidth)
            xLocation = 0;

        dbImageGraphics.clearRect(0, 0, imageWidth, imageHeight);
        dbImageGraphics.drawImage(originalImage, 0, 0, this);
        dbImageGraphics.setColor(Color.red);
        dbImageGraphics.fillOval(xLocation, imageHeight / 2, 20, 20);

        //now dbImage's drawing area appears
        g.drawImage(dbImage, 0, 0, this);

        xLocation++;
        repaint(10);
    }

    public static void main(String[] argv) {
        JFrame frame = new JFrame();
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        DoubleBufferedImage a = new DoubleBufferedImage();

        frame.getContentPane().add(a);
        frame.setSize(300, 300);
        a.init();
        a.start();
        frame.setVisible(true);

    }
}