// StringRoll.java
// Draw Rolling String
// by nagatani@eken.phys.nagoya-u.ac.jp

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

public class StringRoll implements SGObject {

	int	xWindow,	yWindow;
	Image	imageString;
	int	xImage,	yImage;
	
	int	xPosInit,	yPosInit;
	double	deltaY;
	int	xTotalShift;
	int	yOffset;
	
	double	t;
	int	nMode;
	
	StringRoll (Image imageString,
		    int heightString, int yOffset,
		    Applet applet) {
		
		this.imageString = imageString;
		this.yOffset = yOffset;
		this.xWindow = applet.size().width;
		this.yWindow = applet.size().height;
		
		int	xImage = 1026,	yImage = 417;	// 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 (100);	// 100 ms Delay Time
			}
			catch (InterruptedException e) {}
		}
		this.xImage = xImage;
		this.yImage = yImage;
		
		nMode  = 2;
		t = 0.0;
		
		deltaY = (double) (yImage - heightString) / xImage;
		xPosInit = xWindow;
		yPosInit = yWindow/2
			+ (int) (xWindow*deltaY/2) - heightString/2;
		xTotalShift = xImage + xWindow;
	}
	
	public void paint (Graphics g, Applet applet) {
		
		if (nMode == 1) {	// Displaying Mode
			int	xPos,	yPos;
			xPos = (int) (xPosInit - t*xTotalShift);
			yPos = (int) (yPosInit - t*xTotalShift * deltaY);
			g.drawImage (imageString,
				     xPos, yWindow - (yPos + yImage + yOffset),
				     applet);
		}
	}
	
	public void move () {
		
		if (nMode == 0) {	// Reset Mode
			t = 0.0;
			nMode ++;
			return;
		}
		if (nMode == 1) {	// Displaying Mode
			t += 0.01;
			if (t >= 1.0) {
				t = 0.0;
				nMode ++;
			}
			return;
		}
		if (nMode == 2) {	// Sleeping Mode
			t += 0.01;
			if (t >= 0.2) {
				t = 0.0;
				nMode = 0;
			}
			return;
		}
	}
}