/* <applet code=One.class width=600 height=600>

   </applet>
 */ 

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

public class One extends NoFlickerApplet 
                 implements MouseMotionListener,
                            MouseListener {

  Circle[] circles; // array instance variable declared

  public void init() {
    circles = new Circle[400]; // allocate 
    for (int i = 0; i < circles.length; i++) { // initialize
      circles[i] = new Circle(

        (int)(Math.random() * 600), // x 
        (int)(Math.random() * 600), // y 
        (int)(Math.random() * 40 + 10), // r
        new Color((float) Math.random(), 
                  (float) Math.random(), 
                  (float) Math.random())
       ); 
       this.addMouseMotionListener(this);       
       this.addMouseListener(this);       

    }
   
  }

  public void paint(Graphics g) {
    for (int i = 0; i < circles.length; i++)
      circles[i].draw(g); 
  }

  Circle selectedCircle; 

  public void mousePressed(MouseEvent e) { 
    int x = e.getX(), y = e.getY(); 
    for (int i = 0; i < circles.length; i++) {
      if (circles[i].contains(x, y)) {
        selectedCircle = circles[i]; 
        /* return; */ 
      }
    }
  }

  public void mouseDragged(MouseEvent e) { 
    int x = e.getX(), y = e.getY(); 
    if (selectedCircle != null) {
      selectedCircle.move(x, y); 
      repaint();        
    } 
  }
  public void mouseReleased(MouseEvent e) { 
    selectedCircle = null; 
  }

  public void mouseMoved(MouseEvent e) { }
  public void mouseEntered(MouseEvent e) { }
  public void mouseExited(MouseEvent e) { }
  public void mouseClicked(MouseEvent e) { }

}

class Circle { 
  int x, y, radius;
  Color c; 
  Circle(int x, int y, int r, Color c) {
    this.x = x; this.y = y; this.radius = r; this.c = c; 
  }
  void draw(Graphics g) {
    g.setColor(this.c); 
    g.fillOval(this.x, this.y, this.radius * 2, this.radius * 2);
    g.setColor(Color.black); 
    g.drawOval(this.x, this.y, this.radius * 2, this.radius * 2); 
   
  }
  boolean contains(int x, int y) {
    int xC = this.x + this.radius; 
    int yC = this.y + this.radius; 
    double distance = Math.sqrt((xC - x) * (xC - x) + 
                                (yC - y) * (yC - y)); 
    return distance <= radius; 
  }
  void move(int x, int y) {
    this.x = x - this.radius; this.y = y - this.radius; 
  }
}

class NoFlickerApplet extends Applet {
    private Image     offScreenImage;
    private Graphics  offScreenGraphics;
    private Dimension offScreenSize;
    public final void update(Graphics theGraphicsContext){
	Dimension dim = this.getSize(); /* size() originally... */ 
	if( (offScreenImage == null) || 
	    (dim.width != offScreenSize.width) || 
	    (dim.height != offScreenSize.height)) {
	    this.offScreenImage = this.createImage(dim.width, dim.height);
	    this.offScreenSize = dim;
	    this.offScreenGraphics = this.offScreenImage.getGraphics(); 
	}
	this.offScreenGraphics.clearRect(0, 
					 0, 
					 this.offScreenSize.width, 
					 this.offScreenSize.height); 
	this.paint(offScreenGraphics);
	theGraphicsContext.drawImage(this.offScreenImage,
				     0,
				     0,
				     null);
    }
}