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


/*Applet 5 is the same as Applet 4 except that
it implements double buffering.  For
complicated graphical pictures, double
makes for much better plotting.  For the
simple pictures drawn in this applet, 
it doesn't make much difference.  However,
it seems reasonable to introduce it now, in a 
simple setting, since it is extremely useful
in more complicated applets.   Another
new feature of this applet is the introduction
of an auxilliary class in which the graphics
are drawn*/


public class test1 extends Applet {
    PictureCanvas P;    //the auxilliary graphics class
    public void init() {
    setBackground(Color.black);
    P=new PictureCanvas();
    P.resize(300,320);
    add(P);
    }
}



/*This is the class which implements the double
buffering.  The idea is to override the update
command, so as to have the new picture drawn all
at once. */

class DBCanvas extends Canvas {
    
    public void update(Graphics g) {
        Graphics g2;
        Image offscreen = null;
        offscreen = createImage(size().width, size().height);
        g2 = offscreen.getGraphics();
        paint(g2);
        g.drawImage(offscreen, 0, 0, this);
	g2.dispose();
	offscreen.flush();
    }
}


class PictureCanvas extends DBCanvas implements MouseListener {
    Color col; 

    PictureCanvas() { 
      addMouseListener(this);
      setBackground(Color.black);
      col=Color.red;             
    }


  public void paint(Graphics g) {   
      g.setFont(new Font("Helvetica",Font.PLAIN,40));
      g.setColor(Color.yellow);
      g.drawString("Rich: Applet 5",10,40);
      g.setFont(new Font("Helvetica",Font.PLAIN,20));
      g.drawString("Click on the triangle",10,255);
      g.drawString("to change its color.",10,280);
     
      g.setColor(col);
      int x[]={100,100,200};
      int y[]={100,200,200};
      g.fillPolygon(x,y,3);
  }

  public void mousePressed(MouseEvent e) {}    
  public void mouseReleased(MouseEvent e) {} 
  public void mouseEntered(MouseEvent e) {}   
  public void mouseExited(MouseEvent e) {}
  public void mouseClicked(MouseEvent e) {
      e.consume();                         
      if((e.getX()>100)&&(e.getY()<200)&&(e.getX()<e.getY())) {
	Color temp=Color.red;
	if(col==Color.blue) temp=Color.red;
        if(col==Color.red) temp=Color.blue;
	col=temp;
	repaint(100,100,100,100);             
      }
  }
}