/**  Shapes.java
 *   @version 1
 *   @author  Robert M. Keller
 *
 *   Sample applet for displaying Shapes
 **/

/* $Id: Shapes.java,v 1.2 1997/02/10 06:09:35 keller Exp keller $ */

import java.applet.*;		// applet classes
import java.awt.*;		// Abstract Window Toolkit classes
import java.util.*;		// utility classes
import java.lang.Thread;	// Thread class 

/**
 *   Shapes is a simple skeleton applet with double buffered graphics.
 *   It displays two nested shapes and some text.
 **/ 

public class Shapes extends Applet implements Runnable
  {
  static public Color backgroundColor = Color.white;

  static public Font MainFont = new Font("Helvetica", Font.BOLD, 18);

  static public int loopDelay =  10;	   // milliseconds for loop delay

  int maxCycles = 100;			   // cycles in graphic display

  static int fontSize[] = {8, 10, 12, 14, 18, 24};	// font sizes available

  Image image;				   // image which is repainted
  
  Graphics graphics;			   // graphics buffer

  int width, height;			   // width and height of buffer

  Button quitButton = new Button("Quit");  // button to quit the application

  Thread mythread;                         // The applet's thread


  /**
   *   Initialize the applet.
   **/

  public void init()
    {
    setLayout(new FlowLayout(FlowLayout.LEFT));	// layout buttons from left
    setBackground(backgroundColor);		// set the background color

    makeGraphicsBuffer();

    addButton(quitButton);
    }

  // set instance variables for graphics

  void makeGraphicsBuffer()
    {
    width = size().width;
    height = size().height;
    image = createImage(width, height);	
    graphics = image.getGraphics();
    }

  
  void clearGraphicsBuffer()
    {
    graphics.clearRect(0, 0, width, height);    
    }


  // add a button to the applet

  void addButton(Button b)
    {
    b.setFont(MainFont);		
    add(b);
    }

  /**
   *   Run the applet.
   **/

  public void run()
    {
    while(true)
      {
      for( int cycleNumber = 0; cycleNumber < maxCycles; cycleNumber++ )
	{
	cycle(cycleNumber);
	sleep(loopDelay);
	}
      clearGraphicsBuffer();
      }
    }


  /**
   *   Do this every cycle.
   **/

  void cycle(int i)
    {
    String message = "Hello, world";

    // stuff for centering

    float fraction = ((float)i)/maxCycles;
    int width  = (int)(400*fraction);
    int height = (int)(300*fraction);
    int x      = (int)(150*(1-fraction)) + 150;
    int y      = (int)(100*(1-fraction)) + 100;

    // display a centered rectangle

    graphics.setColor(Color.red);
    graphics.fillRect(x, y, width, height);
    
    // display a centered oval

    graphics.setColor(Color.blue);
    graphics.fillOval(x, y, width, height);

    // display message

    graphics.setColor(Color.yellow);
    
    Font font = new Font("Helvetica", Font.BOLD, fontSize[i/17]);
    graphics.setFont(font);
    FontMetrics fontMetrics = graphics.getFontMetrics();
    graphics.drawString(message, 
                        x+width/2-(fontMetrics.stringWidth(message)/2), 
                        y+height/2);

    repaint();
    }


  /**
   *   update is implicitly called by repaint()
   *   It calls paint(Graphics)
   **/

  public void update(Graphics g)
    {
    paint(g);
    }


  /**
   *   paint(Graphics) is is called by update(Graphics)
   **/

  public void paint(Graphics g)
    {
    g.drawImage(image, 0, 0, null);
    }


  /**
   *   action handles events targeted for buttons, etc.
   *   These events do not go to mouseUp etc.
   **/

  public boolean action(Event event, Object arg)
    {
    if( event.target == quitButton )
      {
      destroy();
      }
    return super.action(event, arg);    // Call super
    }


  /**
   *   start is called when the applet is entered, or re-entered.
   **/

  public void start() 
    {
    if( mythread == null )
      {
      mythread = new Thread(this);
      mythread.start();
      }
    else
      mythread.resume();
    }


  /**
   *   stop is called when the applet is left.
   **/

  public void stop() 
    {
    mythread.suspend();
    }


  /**
   *   sleep makes the applet sleep for argument milliseconds
   **/

  public static void sleep(int delay)
    {
    try
      {
      Thread.sleep(delay);
      }
    catch(InterruptedException e)
      {      
      } 
    }
  } // Shapes