// StringFreeRun.java
// Draw String Image and Free Running
// by nagatani@eken.phys.nagoya-u.ac.jp

import java.applet.Applet;
import java.awt.*;

public class StringFreeRun implements SGObject {

	int	xWindow,	yWindow;
	
	public	Image	imageString;
	int	xImage,	yImage;
	
	double	xV,	yV,	xP,	yP;
	
	boolean	bFirst;
	
	StringFreeRun (Image imageString, Applet applet) {
		
		this.imageString = imageString;
		this.xWindow = applet.size().width;
		this.yWindow = applet.size().height;
		
		int	xImage = 50,	yImage = 50;	// Default Image Size
		for (int n = 0 ; n < 10 ; n++) {
			int	x = imageString.getWidth (applet),
				y = imageString.getHeight (applet);
			if (x > 0 && y > 0 ) {
				xImage = x;
				yImage = y;
				break;
			}
			try {
				Thread.sleep (10);	// 10 ms Delay Time
			}
			catch (InterruptedException e) {}
		}
		this.xImage = xImage;
		this.yImage = yImage;
		
		setNewParameters ();
		bFirst = true;
	}
	
	public void paint (Graphics g, Applet applet) {
		
		// Sleeping at the first call
		if (bFirst)
			return;
		
		g.drawImage (imageString, (int) xP, (int) yP, applet);
	}
	
	public void move () {
		
		// Sleeping at the first call
		if (bFirst && Math.random () > 0.05)
			return;
		
		bFirst = false;
		
		xP += xV;
		yP += yV;
		
		if (yP < 0 || xP > xWindow || yP > yWindow)
			setNewParameters ();
	}
	
	private void setNewParameters () {
		
		xP = -1.0 * xImage;
		yP =  1.0 * (yWindow - yImage) * Math.random ();
		xV =  2.0 + 10.0 * Math.random ();
		yV = -0.5 +  1.0 * Math.random ();
	}
}