//RandomLines.java
import java.awt.*;
import java.awt.event.*;   //**ActionListener interface
import javax.swing.*;

public class RandomLines extends JApplet implements ActionListener {
                                         //**
    JLabel linesLabel, equalLengthLabel, maxLengthLabel;
    JTextField linesField, equalLengthField, maxLengthField;
    JButton againButton;

    public void init() {     //sets up the GUI

	//**represents contents of applet area:
	Container container = getContentPane();  
	//**widgets laid out left to right in order added:
	container.setLayout( new FlowLayout() ); 
	
	//**create a JLabel object:
	linesLabel = new JLabel( "Number of lines" );
	//**add it to the applet contents:
	container.add( linesLabel );
	//**create a JTextField object:
	linesField = new JTextField( 4 );   //length in chars
	container.add( linesField );
	
	equalLengthLabel = new JLabel( "All equal length?" );
	container.add( equalLengthLabel );
	equalLengthField = new JTextField( "no",4 );  //default value
	container.add( equalLengthField );

	maxLengthLabel = new JLabel( "Max. length" );
	container.add( maxLengthLabel );
	maxLengthField = new JTextField( 4 );
	container.add( maxLengthField );
	
	//create a JButton object:
	againButton = new JButton( "Again! Again!" );
	container.add( againButton );
	//**press of button event will be handled by this applet:
	//**"register" the event handler
	againButton.addActionListener( this );
    }

    //**required method if implementing ActionListener.
    //**automatically called upon certain actions (events) that have 
    //been registered by .addActionListener(this)
    public void actionPerformed( ActionEvent event ) {
	//**check if source of the event is our JButton:
	if ( event.getSource() == againButton ) 
	    repaint();    //**calls paint
	//could do other code but this is all that is needed for this program
    }
    
    
    public void paint( Graphics g ) {
	int x1, y1, x2, y2;
	double angle;
	int lines;
	int length;
	int maxLength;
	boolean equalLengthLines;
	
	//** clears applet area.  also displays the GUI components.
	super.paint( g );
	
	//random point (x1,y1)  then random point in circle of maxLength radius
	//around it
	
	//**get the string text of a JTextField object
	length =    Integer.parseInt(maxLengthField.getText());
	maxLength = Integer.parseInt(maxLengthField.getText());
	
	lines = Integer.parseInt(linesField.getText());
	
	if (equalLengthField.getText().equals("yes"))
	    equalLengthLines = true;
	else
	    equalLengthLines = false;
	
	for (int i=1; i<=lines; i++) {
	    //random point
	    x1 = (int)(Math.random() * getWidth());
	    y1 = (int)(Math.random() * getHeight());
	    //random angle
	    angle = Math.random() * 2 * Math.PI;    //radians
	    if (!equalLengthLines)  //random length
		length = (int)(Math.random() * maxLength);
	    //other endpoint is angle degrees 
	    x2 = (int)(Math.cos(angle) * length + x1);
	    y2 = (int)(Math.sin(angle) * length + y1);
	    
	    g.drawLine(x1,y1,x2,y2);
	}
	/*
	//test if draws to edge or draws nothing
	//draws to edges!
	g.drawLine(10,10,-10,-10);
	g.drawLine(700,100,900,100);
	*/
    }
}