Final Project Applet

/**
 * import statements
**/
import java.awt.*;
import javax.swing.*;
import java.awt.event.*;
import java.applet.Applet;
public class Spiro extends Applet implements ActionListener
{
        // declare variables
	private Label lblOrder, lblAngle, lblIterate, lblUnit, lblInst1;
        private Label lblInst2, lblInst3, lblInst4, lblInst5, lblInst6, lblInst7;
	private TextField txtOrder, txtAngle, txtIterate, txtUnit;
	private Button instruct, make;
        int order, angle;
	int border=0, bangle=0, unit;
        //here the strings which make the instruction set are initialized
        String message="A Spirolateral is a type of path specified by a certain type of recursive algorithm. This program uses an algorithm";
        String message2="based on right turns, though figures with lefts, or lefts and rights, are also possible.  The variables involved ";
        String message3="are the angle of the turn, the number of turns to take(the `order'), the unit length, and the number of iterations";
        String message4="to perform.  Each time a turn is made, the next line is increased in length by one more unit.  Some combinations";
        String message5="of values will spill off the screen, or trail in unexpected directions. There is no known method to prove before-";
        String message6="hand whether a given spirolateral will be a closed form, or not.  Many interesting results can be found using";
        String message7="angles of 30, 45, 60, 72, 90, 108, 120, 135, and 150...";
        // the init method; it inits
	public void init()
	{
		lblUnit=new Label("Unit size: ");
                txtUnit=new TextField(15);
                lblOrder=new Label("Order: ");
		txtOrder = new TextField(15);
		lblInst1=new Label(message);
                lblInst2=new Label(message2);
                lblInst3=new Label(message3);
                lblInst4=new Label(message4);
                lblInst5=new Label(message5);
                lblInst6=new Label(message6);
                lblInst7=new Label(message7);
		lblAngle=new Label("Angle: ");
		txtAngle=new TextField(15);
                lblIterate=new Label("Iterations: ");
                txtIterate=new TextField(15);
                make=new Button("Make a Spirolateral!");
		add(lblInst1);
                add(lblInst2);
                add(lblInst3);
                add(lblInst4);
                add(lblInst5);
                add(lblInst6);
                add(lblInst7);
                add(lblUnit);
                add(txtUnit);
                add(lblOrder);
		add(txtOrder);
		add(lblAngle);
		add(txtAngle);
                add(lblIterate);
                add(txtIterate);
		add(make);
                // if any clarification is needed for the above code, you
                // should go read a java book.  next line adds and actionlistener
                // to make
		make.addActionListener(this);
                // sets some defaults to avoid runtime errors
		txtUnit.setText("3");
                txtOrder.setText("27");
                txtAngle.setText("135");
                txtIterate.setText("8");
	}
	public void actionPerformed ( ActionEvent event )
	{
                //this is simple; repaints, using whatever the new values are
		repaint();
	}//end actionPerformed
	
	
	public void paint(Graphics foo)
	{
		int length=50;
		int firstx= 320, firsty=350;
		int unit=3, bunit, biterate, iterate;
				
		foo.setColor(Color.gray);
                foo.fillRect(5, 230, 690, 550);
		
                // this catches any case where a non-integer or too large a number is in the TextField(s)
                // will also catch blank (empty) strings of non-numeric characters.
                try {
                    border = Integer.parseInt(txtOrder.getText());
                    bangle = Integer.parseInt(txtAngle.getText());
                    bunit = Integer.parseInt(txtUnit.getText());
                    biterate = Integer.parseInt(txtIterate.getText());  }
                catch (NumberFormatException e){
                    border=0; bangle=0; bunit=0;biterate=0; }
		
                // this block initializes some default values, to make one of the prettier spirolaterals
		if (border > 0)
			order=border;
		else 
			order=27;
		if (bunit > 0)
			unit=bunit;
		else 
			unit=3;
                
                if (biterate > 0)
			iterate=biterate;
		else 
			iterate=9;
		
		int x=firstx;
		int y=firsty;
		
		if (bangle > 0)
			angle=bangle;
		else
			angle=135;
		
		int nangle=0;
		
                // this loop does the work.  it calls getX and getY methods to find
                // endpoints for lines...
		for (int j=1; j<=iterate; j++)
		{
			for (int i=1; i<=order; i++)
			{
				newColor(i, foo);
				nangle=nangle+angle;
				int nx=getX(i * unit, nangle, x);
				int ny=getY(i * unit, nangle, y);
				foo.drawLine(x, y, nx, ny);
				x=nx;
				y=ny;
				
				 	
			}
		}
	}
	
        // the next two methods find the x,y points respectively of a line of length
        // length, and angle angle.  If this doesn't make sense, try to modify them,
        // compile and attempt to run.  You should see what they do soon enough
	public int getX(int length, int angle, int x)
	{
		return x + (int)(length * Math.cos(angle * Math.PI / 180));	
	}
	public int getY(int length, int angle, int y)
	{
		return y + (int)(length * Math.sin(angle * Math.PI / 180));	
	}
	
        // this method simply picks a new color, cycling through a list each time.
        // could be done better, but i'm tired and it works fine
	public void newColor(int n, Graphics foo)
	{
		if (n>24)
			n=n-24;
		else if (n>16)
			n=n-16;
		else if (n>8)
			n=n-8;
		switch(n)
		{
		case 1:
			foo.setColor(Color.blue);
			break;
		case 2:
			foo.setColor(Color.red);
			break;
		case 3:
			foo.setColor(Color.green);
			break;
		case 4:
			foo.setColor(Color.orange);
			break;
		case 5:
			foo.setColor(Color.cyan);
			break;
		case 6:
			foo.setColor(Color.yellow);
			break;
		case 7:
			foo.setColor(Color.pink);
			break;
		case 8:
			foo.setColor(Color.magenta);
			break;
		default:
			foo.setColor(Color.black);
			break;
		}
	}	
}