/**  
 * AppletGraphics.java
 * @author  Robert M. Keller
 *
 * Skeleton class for building an applet, with double buffering.
 */

import java.applet.*;		// applet classes
import java.awt.*;		// Abstract Window Toolkit classes

/**
 *   AppletGraphics is a skeleton applet with double buffered graphics.
 */ 

public class AppletGraphics extends Applet
  {
  String message = "A 300 x 100 box";

  int boxWidth = 300;
  int boxHeight = 100;

  Color backgroundColor = Color.white;
  Color foregroundColor = Color.black;

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

  Image image;				// image holding the graphics buffer
  
  Graphics graphics;			// graphics buffer

  /**
   *   Initialize the applet.
   */

  public void init()
    {
    setBackground(backgroundColor);

    // size().width and size().height are deprecated and normally would
    // be replaced with getWidth() and getHeight(). However, the latter
    // do not work with some browsers.

    // make an off-screen graphics buffer

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


  /**
   *  Start the applet.
   */

  public void start()
    {
    drawBox();
    }


  /**
   * An example: 
   * Drawing a box containing a message indicating the size of the box,
   * with a dividing line.
   */

  void drawBox()
    {
    // Get the dimensions of the window.

    int windowWidth = Integer.parseInt(getParameter("width"));
    int windowHeight = Integer.parseInt(getParameter("height"));

    // Fill the background.

    graphics.setColor(backgroundColor);
    graphics.fillRect(0, 0, windowWidth, windowHeight);

    // Set up for drawing.

    graphics.setColor(foregroundColor);

    // Draw a rectangle centered in the window.

    graphics.drawRect((windowWidth - boxWidth)/2, 
                      (windowHeight - boxHeight)/2, 
                      boxWidth, 
                      boxHeight);

    // Draw a horizontal line centered in the rectangle.

    graphics.drawLine((windowWidth-boxWidth)/2, windowHeight/2,
                      (windowWidth+boxWidth)/2, windowHeight/2);

    // Draw the message.

    graphics.setFont(MainFont);

    FontMetrics metrics = graphics.getFontMetrics();

    int stringWidth = metrics.stringWidth(message);
    int stringHeight = metrics.getHeight();

    graphics.drawString(message, 
                        (windowWidth  - stringWidth)/2,
                        (windowHeight - stringHeight)/2);
    }


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

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


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

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