import java.awt.Container;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Rectangle;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseMotionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;

import javax.swing.JFrame;
import javax.swing.JPanel;

public class MouseMovement extends JPanel implements MouseMotionListener {
  private static final int SquareWidth = 10;

  private static final int Max = 100;

  private Rectangle[] squares = new Rectangle[Max];

  private int squareCount = 0;

  private int currentSquareIndex = -1;

  public MouseMovement() {
    addMouseListener(new MouseAdapter() {
      public void mousePressed(MouseEvent evt) {
        int x = evt.getX();
        int y = evt.getY();
        currentSquareIndex = getSquare(x, y);
        if (currentSquareIndex < 0) // not inside a square
          add(x, y);
      }

      public void mouseClicked(MouseEvent evt) {
        int x = evt.getX();
        int y = evt.getY();

        if (evt.getClickCount() >= 2) {
          remove(currentSquareIndex);
        }
      }
    });
    addMouseMotionListener(this);
  }

  public void paintComponent(Graphics g) {
    super.paintComponent(g);
    for (int i = 0; i < squareCount; i++)
      ((Graphics2D)g).draw(squares[i]);
  }

  public int getSquare(int x, int y) {
    for (int i = 0; i < squareCount; i++)
      if(squares[i].contains(x,y))
        return i;
    return -1;
  }

  public void add(int x, int y) {
    if (squareCount < Max) {
      squares[squareCount] = new Rectangle(x, y,SquareWidth,SquareWidth);
      currentSquareIndex = squareCount;
      squareCount++;
      repaint();
    }
  }

  public void remove(int n) {
    if (n < 0 || n >= squareCount)
      return;
    squareCount--;
    squares[n] = squares[squareCount];
    if (currentSquareIndex == n)
      currentSquareIndex = -1;
    repaint();
  }

  public void mouseMoved(MouseEvent evt) {
    int x = evt.getX();
    int y = evt.getY();

    if (getSquare(x, y) >= 0)
      setCursor(Cursor.getPredefinedCursor(Cursor.CROSSHAIR_CURSOR));
    else
      setCursor(Cursor.getDefaultCursor());
  }

  public void mouseDragged(MouseEvent evt) {
    int x = evt.getX();
    int y = evt.getY();

    if (currentSquareIndex >= 0) {
      Graphics g = getGraphics();
      g.setXORMode(getBackground());
      ((Graphics2D)g).draw(squares[currentSquareIndex]);
      squares[currentSquareIndex].x = x;
      squares[currentSquareIndex].y = y;
      ((Graphics2D)g).draw(squares[currentSquareIndex]);
      g.dispose();
    }
  }

  public static void main(String[] args) {
    JFrame frame = new JFrame();
    frame.setTitle("MouseTest");
    frame.setSize(300, 200);
    frame.addWindowListener(new WindowAdapter() {
      public void windowClosing(WindowEvent e) {
        System.exit(0);
      }
    });

    Container contentPane = frame.getContentPane();
    contentPane.add(new MouseMovement());

    frame.show();
  }
}