//
// another example of the Java AWT, showing creation of an Image
//      an image.
// see class definition for details.
//
// this example is modified from a similar example in chapter 17 of
//      _Exploring Java_ (Niemeyer and Peck).
//
import java.awt.* ;
import java.awt.event.* ;
import java.awt.image.* ;

//
// a BlackWhiteStatic object is a DrawingFrame that displays a "static"
//	(random colors) image.  the image changes periodically.
//      if the window is resized, the image is scaled to fit.
//
class BlackWhiteStatic extends DrawingFrame 
		implements ComponentListener, Runnable {

	private Image img ;
	private int imgWidth, imgHeight ;
	private int pixelData[] ;
	private MemoryImageSource imgSource ;
	private int refreshRate ;

        BlackWhiteStatic(Dimension dims, int refr) {

		super("BlackWhiteStatic") ;
		setDrawingSize(dims) ;
		refreshRate = refr ;
		initializeImage(dims) ;
		addComponentListener(this) ;

		// start thread to change image periodically
		new Thread(this).start() ;

		show() ;
	}

	// initializes image -- sets up width, height, pixel data
	//	array.
	private void initializeImage(Dimension dims) {
		imgWidth = dims.width ;
		imgHeight = dims.height ;
		pixelData = new int [imgWidth * imgHeight] ;
		imgSource = new MemoryImageSource(imgWidth, imgHeight,
			pixelData, 0, imgWidth) ;
		imgSource.setAnimated(true) ;
		img = createImage(imgSource) ;
	}

	// generates random static, every refreshRate milliseconds.
	public void run() {
		while (true) {
			try {
				Thread.sleep(refreshRate) ;
			} catch (InterruptedException e) {
				// should not happen
			}
			int i=0 ;
			for (int col = 0 ; col < imgWidth ; col++) {
			for (int row = 0 ; row < imgHeight ; row++) {
				boolean rand = (Math.random() > 0.5) ;
				pixelData[i++] =
					rand ? Color.black.getRGB() :
						Color.white.getRGB() ;
			}
			}
			System.out.println("updating image data") ;
			imgSource.newPixels(0, 0, imgWidth, imgHeight) ;
		}
	}
	

	// creates onscreen image from pixel data.
	public void paint(Graphics g) {

		System.out.println("paint called") ;

		// position origin to avoid frame borders.
		translateDrawingArea(g) ;

		// draw image.
		g.drawImage(img, 0, 0, this) ;
	}

	// updates onscreen image (no need to clear first, just paint).
	public void update(Graphics g) {
		System.out.println("update called") ;
		paint(g) ;
	}

	// called when component is resized.
	public void componentResized(ComponentEvent e) { 
		System.out.println("componentResized called") ;
		initializeImage(getDrawingSize()) ;
		repaint() ;
	}

	// other methods of ComponentListener interface.
	public void componentHidden(ComponentEvent e) { }
	public void componentMoved(ComponentEvent e) { }
	public void componentShown(ComponentEvent e) { }


	//
	// ---- main ---------------------------------------------------
	//
	// command-line arguments:  initial width, height, 
	//	refresh rate in milliseconds (defaults 400, 200, 1000)
	//
	public static void main(String[] args) {

		int w = 400 ;
		int h = 200 ;
		int r = 1000 ;
		if (args.length >= 3) {
			w = Integer.parseInt(args[0]) ;
			h = Integer.parseInt(args[1]) ;
			r = Integer.parseInt(args[2]) ;
		}

		BlackWhiteStatic c = 
			new BlackWhiteStatic(new Dimension(w, h), r) ;
	}
}