// file:    MyApplet3.java
// author:  Robert M. Keller
// purpose: Demonstrate use of off-screen buffer
//          Prints trace messages

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

public class MyApplet3 extends Applet
{
Image buffer;                  // Image to be drawn on screen by paint method
Graphics graphics;             // Graphics part of image, acts as buffer

// Initialize the applet.

public void init()
  {
  System.out.println("*** init() called");
  buffer = createImage(size().width, size().height);     
  graphics = buffer.getGraphics();
  }

// Called to start the applet after init.

public void start()
  {
  System.out.println("*** start() called");
  drawStuff(graphics);
  repaint();
  }


// repaint over-ride is just for purposes of tracing

public void repaint()
  {
  System.out.println("*** repaint() called");
  super.repaint();
  }


// update is implicitly called when repaint() is called
// g will be bound to the Graphics object in the Applet,
// not the one in the buffer.  paint will draw the buffer into g.

public void update(Graphics g)
  {
  System.out.println("*** update() called");
  paint(g);
  }


// draw items in Graphics

void drawStuff(Graphics g)
  {
  System.out.println("*** drawStuff() called");
  // dimensions and offsets
  int xCenter = 250;
  int yCenter = 200;
  int rectWidth = 400;
  int rectHeight = 300;
  int ovalWidth = 300;
  int ovalHeight = 200;

  String hmc = "Harvey Mudd College";
  g.setFont(new Font("Times", Font.BOLD, 20));  
  int stringOffset = xCenter - g.getFontMetrics().stringWidth(hmc)/2;
  int stringBase = 10 + yCenter;

  // background color
  g.setColor(Color.white);
  g.fillRect(0, 0, size().width, size().height);

  // shapes
  g.setColor(Color.black);
  g.drawRect(xCenter-rectWidth/2, yCenter-rectHeight/2, rectWidth, rectHeight);
  g.fillOval(xCenter-ovalWidth/2, yCenter-ovalHeight/2, ovalWidth, ovalHeight);

  // lettering
  g.setColor(Color.yellow);
  g.drawString("Harvey Mudd College", stringOffset, stringBase);
  }


// paint(Graphics) is called by update(g) and whenever 
// the screen needs painting (such as when it is newly exposed)

public void paint(Graphics g)
  {
  System.out.println("*** paint() called");
  g.drawImage(buffer, 0, 0, null);
  }
}