// File: TestApplet.java (Module 9)
//
// Author: Rahul Simha
// Created: October 21, 1998
//
// Panels and canvases - in an applet.

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

public class TestApplet extends Applet
  implements ActionListener, MouseListener {

  // Data.
  Button quitb, clearb, startb;
  Canvas c;
  Panel p;
  boolean start = false;

  // Constructor.
  public void init()
  {
    // Title and size cannot be set in an applet.
    this.setBackground (Color.cyan);

    // Create a quit button.
    quitb = new Button ("Quit");
    quitb.setBackground (Color.red);
    quitb.setFont (new Font ("Serif", Font.PLAIN | Font.BOLD, 15));
    quitb.addActionListener (this);

    // Default for an applet is FlowLayout.
    this.setLayout (new BorderLayout());
    this.add (quitb, BorderLayout.SOUTH);

    // Create a white canvas.
    c = new Canvas ();
    c.setBackground (Color.white);
    c.setForeground (Color.blue);
    c.addMouseListener (this);

    // Add canvas to frame in the center.
    this.add (c, BorderLayout.CENTER);

    // Create a Panel
    p = new Panel ();
    p.setLayout (new FlowLayout());

    // Create a clear button.
    clearb = new Button ("Clear");
    clearb.addActionListener (this);
    clearb.setBackground (Color.green);

    // Create a start button.
    startb = new Button ("Start");
    startb.addActionListener (this);
    startb.setBackground (Color.green);

    // Add start and clear buttons to panel.
    p.add (clearb);
    p.add (startb);

    // Now add the panel to the frame.
    this.add (p, BorderLayout.NORTH);

    // Show the frame.
    this.setVisible (true);
  }

  // This method is required to implement the 
  // ActionListener interface.
  public void actionPerformed (ActionEvent a)
  {
    String s = a.getActionCommand();
    if (s.equalsIgnoreCase ("Quit"))
      System.exit(0);
    else if (s.equalsIgnoreCase ("Clear")) {
      // Note: must call repaint() of canvas
      // to reset the background.
      c.setBackground (Color.white);
      c.repaint ();
      current_x = current_y = 0;
    }
    else if (s.equalsIgnoreCase ("Start"))
      start = true;
  }

  int current_x=0, current_y=0;

  // These methods are required to implement 
  // the MouseListener interface.
  public void mouseClicked (MouseEvent m)
  {
    if (!start) // User must click start once to draw.
      return;
    int x = m.getX();
    int y = m.getY();
    Graphics g = c.getGraphics();
    g.drawLine (current_x, current_y, x, y);
    current_x = x;
    current_y = y;
  }

  // We need to implement these methods, but
  // don't actually have to do anything inside.
  public void mouseEntered (MouseEvent m) {}
  public void mouseExited (MouseEvent m) {}
  public void mousePressed (MouseEvent m) {}
  public void mouseReleased (MouseEvent m) {}

} // End of class "TestApplet"