import java.awt.* ;
import java.awt.event.* ;

/**
 * <dl>
 * <dt>Purpose: Simple drawing program with exit option.
 * <dd>
 *
 * <dt>Description:
 * <dd>Draws a diagonal line in a window.
 * </dl>
 *
 * @author  Richard Akester
 * @version $Date: 2005/10/18$
 * 
 */
 
public class MyDrawLine extends Frame
{
  static class DrawArea extends Panel
  { 
    public void paint(Graphics g)
    {
        int xStart=0, yStart=0;

        // iterate along the longest side (to avoid dotted lines)
        if(WIDTH > HEIGHT) {
            // Calculate c (as in y=mx+c) avoiding divide by 0.
            int c= WIDTH==0? 0 : yStart - xStart*HEIGHT/WIDTH;
		int xEnd=xStart+WIDTH;

            for(int x=xStart; x<xEnd; x++) {
                g.drawRect(x, x*HEIGHT/WIDTH + c, 1, 1);
            }
        } else {
            // Swap the axes: WIDTH<->HEIGHT, xStart<->yStart
            int c= HEIGHT==0? 0 : xStart - yStart*WIDTH/HEIGHT;
		int yEnd=yStart+HEIGHT;

	      for(int y=yStart; y<yEnd; y++) {
	          g.drawRect(y*WIDTH/HEIGHT + c, y, 1, 1);
            }
        }
    }

    public Dimension getPreferredSize()
    {
      return new Dimension(WIDTH,HEIGHT);
    }

    private int WIDTH = 100;
    private int HEIGHT = 600;
  }

  public MyDrawLine(String name)
  {
    super(name);
  } 
  
  private static void quit()
  {
    System.exit(0);
  }

  public static void main(String[] args)
  {
     MyDrawLine frame = new MyDrawLine("My DrawLine");

     DrawArea drawing = new DrawArea();
     Panel buttonPanel = new Panel();
     buttonPanel.setLayout(new BorderLayout());
     Button quitButton = new Button("Quit");
     buttonPanel.add("Center",quitButton);
     frame.setLayout(new BorderLayout());
     frame.add("Center",drawing);
     frame.add("South",buttonPanel);

     quitButton.addActionListener(new ActionListener()
     {
       public void actionPerformed(ActionEvent evt)
       {
         quit();
       }
     });

     frame.addWindowListener(new WindowAdapter()
     {
       public void windowClosing(WindowEvent evt)
       {
         quit();
       }
     });

     frame.pack();
     frame.setVisible(true);
  }
}