import java.awt.*;
import java.awt.event.*;
import java.applet.Applet;
/** (C) 2000 Charles Consulting, LLC <br>
Class to draw radial line art image. Parameters allow the radius increment,
angle increment, and number of steps to be varied. May be run as Applet
or application */

public class Spinner extends StandAloneApplet {

	private double angle;
	private int radius;
	private int angleStep = 90;
	private int radiusStep = 0;
	private int nStep = 100;
	private int originX; 
	private int originY; 
	private RepaintListener repaintListener = new RepaintListener( );
    private	IntegerPanel anglePanel = new IntegerPanel("Angle increment",angleStep,1,360);
    private	IntegerPanel radiusPanel = new IntegerPanel("Radius step",radiusStep,0,100);
    private	IntegerPanel stepPanel = new IntegerPanel("Number steps",nStep,1,1000);
	private Panel controlPanel = new Panel( );

	Canvas canvas = new Canvas() {
		public void paint(Graphics g)
		{
			Dimension size = getSize( );
			final int height = size.height;
			final int width = size.width;
			radius = Math.min(height, width)/2;
			originX = width/2;
			originY = height/2;
			angle = 0;
			Point from = new Point( ); 
			Point to = new Point(0,0);
			double dAngle = angle; 
			int r = radius;
			setPoint(from,radius,dAngle);
			for (int i=0;i<nStep+20;i++)
				{
				dAngle += angleStep; 
				dAngle %= 360;
				setPoint(to,r,dAngle);
				if (i>=20)
					drawLine(g,from,to);
				from.setLocation(to);
				r -= radiusStep;
				while (r <= 0)
					r += radius;
				}
		}
	};

	/** called to initialize Applet */
	public void init( )
	{
		setLayout(new BorderLayout( ));
		add(canvas,BorderLayout.CENTER);
		anglePanel.addActionListener(repaintListener);
		radiusPanel.addActionListener(repaintListener);
		stepPanel.addActionListener(repaintListener);
		controlPanel.setLayout(new GridLayout(4,1));
		controlPanel.add(anglePanel);
		controlPanel.add(radiusPanel);
		controlPanel.add(stepPanel);
		add(controlPanel,BorderLayout.SOUTH);
		setForeground(Color.red);
	}

	/** set specified point based on polar coordinates */
	private final void setPoint(Point p,double r,double a)
	{
		final double sinVal = angleSine(a); 
		final double cosVal = angleCosine(a); 
		double x = r *  sinVal;
		double y = r * cosVal; 
		p.setLocation((int)x,(int)y);
	}

	/* return the sine of an angle in degrees */
	private final double angleSine(double a)
	{
		return Math.sin(a * Math.PI/180);
	}

	/* return the cosine of an angle in degrees */
	private final double angleCosine(double a)
	{
		return Math.cos(a * Math.PI/180);
	}

	/** draw a line betweent two points */
	private final void drawLine(Graphics g,Point from, Point to)
	{
		int x1 = (int)from.x + originX;
		int y1 = (int)from.y + originY;
		int x2 = (int)to.x + originX;
		int y2 = (int)to.y + originY;
		g.drawLine(x1,y1,x2,y2);
	}

	private class RepaintListener implements ActionListener {
		/** common listener object */
		public void actionPerformed(ActionEvent e) 
		{
			angleStep = anglePanel.getValue( );
			radiusStep = radiusPanel.getValue( );
			nStep = stepPanel.getValue( );
			canvas.repaint( );
		}
	}

	/** implement super abstract method */
	public String getTitle( )
	{
		return "Spinner";
	}

	/** main used for application mode */
	public static void main(String args[])
	{
		Spinner spinner = new Spinner( );
		spinner.setupApplet(args);
	}
}