Draw a square with the cursor

Question

i would like to draw a square with the movement of the coursor, while its left button is clicked and the cursor is over an image.
when i leave of pushing the right button the square have to dissapear.
if you don't understand, it's the same in windows when you click the left button and square appears.
My question is how can i do this?
thanks

Answer 1

Not sure I completely understand the question, but maybe this will give you an idea:
import java.util.*;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class DrawSquare extends JPanel
     Point startPoint = null;
     Point endPoint = null;
     public DrawSquare()
          setPreferredSize(new Dimension(500,500));
          MyMouseListener ml = new MyMouseListener();
          addMouseListener(ml);
          addMouseMotionListener(ml);
          setBackground(Color.white);
     public void paintComponent(Graphics g)
          // automatically called when repaint
          super.paintComponent(g);
          g.setColor(Color.black);
          if (startPoint != null && endPoint != null)
               // draw the current dragged line
               int x = Math.min(startPoint.x, endPoint.x);
               int y = Math.min(startPoint.y, endPoint.y);
               int width = Math.abs(endPoint.x - startPoint.x);
               int height = Math.abs(endPoint.y - startPoint.y);
               g.drawRect(x, y, width, height);
     class MyMouseListener extends MouseInputAdapter
          public void mousePressed(MouseEvent e)
               if (SwingUtilities.isLeftMouseButton(e))
                    startPoint = e.getPoint();
                    repaint();
          public void mouseReleased(MouseEvent e)
               if (SwingUtilities.isLeftMouseButton(e))
                    startPoint = null;
                    endPoint = null;
//                    repaint();
          public void mouseDragged(MouseEvent e)
               if (SwingUtilities.isLeftMouseButton(e))
                    endPoint = e.getPoint();
                    repaint();
     public static void main(String[] args)
          JFrame frame = new JFrame();
          frame.setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
          DrawSquare d = new DrawSquare();
          frame.getContentPane().add( d );
          frame.pack();
          frame.setVisible(true);
}