DragUsingInnerClasses

import acm.program.*;
import acm.graphics.*;
import java.awt.*;
import java.awt.event.*;
 
public class DragUsingInnerClasses extends GraphicsProgram {
 
	public void init() {
		GRect rect = new GRect(100, 100, 150, 100);
		rect.setFilled(true);
		rect.setColor(Color.RED);
		add(rect);
 
		GOval oval = new GOval(300, 115, 100, 70);
		oval.setFilled(true);
		oval.setColor(Color.GREEN);
		add(oval);
 
		GCanvas canvas = getGCanvas();
		canvas.addMouseListener(new MouseAdapter() {
			public void mousePressed(MouseEvent e) {
				last = new GPoint(e.getPoint());
				gobj = getElementAt(last);
			}
 
			public void mouseClicked(MouseEvent e) {
				if (gobj != null) gobj.sendToFront();
			}
		});
 
		canvas.addMouseMotionListener(new MouseMotionAdapter() {
			public void mouseDragged(MouseEvent e) {
				if (gobj != null) {
					gobj.move(e.getX() - last.getX(),
							  e.getY() - last.getY());
					last = new GPoint(e.getPoint());
				}
			}
		});
	}
 
	/* Private instance variables */
	private GObject gobj;	/* The object being dragged */
	private GPoint last;	/* The last mouse position  */
 
	private static final long serialVersionUID = 1;
}