slideshow.java

Java Thread Programming (Source

import java.awt.*;
import java.awt.image.*;
import javax.swing.*;

public class SlideShow extends JComponent {
	private BufferedImage[] slide;
	private Dimension slideSize;
	private volatile int currSlide;

	private Thread internalThread;
	private volatile boolean noStopRequested;

	public SlideShow() {
		currSlide = 0;
		slideSize = new Dimension(50, 50);
		buildSlides();

		setMinimumSize(slideSize);
		setPreferredSize(slideSize);
		setMaximumSize(slideSize);
		setSize(slideSize);

		noStopRequested = true;
		Runnable r = new Runnable() {
				public void run() {
					try {
						runWork();
					} catch ( Exception x ) {
						// in case ANY exception slips through
						x.printStackTrace(); 
					}
				}
			};

		internalThread = new Thread(r, "SlideShow");
		internalThread.start();
	}

	private void buildSlides() {
		// Request that the drawing be done with anti-aliasing
		// turned on and the quality high.
		RenderingHints renderHints = new RenderingHints(
			RenderingHints.KEY_ANTIALIASING,
			RenderingHints.VALUE_ANTIALIAS_ON);

		renderHints.put(
			RenderingHints.KEY_RENDERING,
			RenderingHints.VALUE_RENDER_QUALITY);

		slide = new BufferedImage[20];

		Color rectColor = new Color(100, 160, 250);   // blue
		Color circleColor = new Color(250, 250, 150); // yellow

		for ( int i = 0; i < slide.length; i++ ) {
			slide[i] = new BufferedImage(
					slideSize.width,
					slideSize.height,
					BufferedImage.TYPE_INT_RGB);

			Graphics2D g2 = slide[i].createGraphics();
			g2.setRenderingHints(renderHints);

			g2.setColor(rectColor);
			g2.fillRect(0, 0, slideSize.width, slideSize.height);

			g2.setColor(circleColor);

			int diameter = 0;
			if ( i < ( slide.length / 2 ) ) {
				diameter = 5 + ( 8 * i );
			} else {
				diameter = 5 + ( 8 *  ( slide.length - i ) );
			}

			int inset = ( slideSize.width - diameter ) / 2;
			g2.fillOval(inset, inset, diameter, diameter);

			g2.setColor(Color.black);
			g2.drawRect(
				0, 0, slideSize.width - 1, slideSize.height - 1);

			g2.dispose();
		}
	}

	public void paint(Graphics g) {
		g.drawImage(slide[currSlide], 0, 0, this);
	}

	private void runWork() {
		while ( noStopRequested ) {
			try {
				Thread.sleep(100);  // 10 frames per second
				
				// increment the slide pointer
				currSlide = ( currSlide + 1 ) % slide.length;

				// signal the event thread to call paint()
				repaint();
			} catch ( InterruptedException x ) {
				Thread.currentThread().interrupt(); 
			}
		}
	}

	public void stopRequest() {
		noStopRequested = false;
		internalThread.interrupt();
	}

	public boolean isAlive() {
		return internalThread.isAlive();
	}

	public static void main(String[] args) {
		SlideShow ss = new SlideShow();

		JPanel p = new JPanel(new FlowLayout());
		p.add(ss);

		JFrame f = new JFrame("SlideShow Demo");
		f.setContentPane(p);
		f.setSize(250, 150);
		f.setVisible(true);
	}
}