CODEWITHSUNDEEP
javaswing
Abby
Abby

Reputation: 316

How can I draw a blue rectangle when mouse is pressed?

Here is my code. I want to draw a blue rectangle when the mouse is pressed. The rectangle would be centred around the mouse pointer. I am a noob to events, so I would appreciate help and explanations.

import javax.swing.*; 
import java.awt.*; 
import java.awt.event.*;  

 class MouseDemo extends JPanel implements MouseListener {
     int x, y; // location of mouse
     int sx=25, sy=25; // size of shape 
     JFrame frame;

     void buildIt() {     
         frame = new JFrame("MouseDemo");
         frame.add( this );
         this.x = 150;
         this.y = 150;
         this.addMouseListener(this); 
         frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
         frame.setSize(300, 300);
         frame.setLocation(200, 200);
         frame.setVisible(true);
     }

     public void paintComponent(Graphics g) {
         super.paintComponent(g);
         g.setColor( Color.blue );
         g.fillRect(x - sx/2, y - sy/2, sx, sy);
     }    

     // the method from MouseListener we're interested in this time
     @Override
     public void mousePressed( MouseEvent e) {
         e.getX();
         e.getY();
     }   

     // the other four methods from MouseListener
     // we don't use them, but they have to be present
     @Override public void mouseReleased( MouseEvent e) { }
     @Override public void mouseClicked( MouseEvent e) { }
     @Override public void mouseEntered( MouseEvent e) { }
     @Override public void mouseExited( MouseEvent e) { }

     public static void main(String[] args) {
         new MouseDemo().buildIt(); 
     }
}

Upvotes: 2

Views: 187

Answers (1)

Tadija Bagarić
Tadija Bagarić

Reputation: 2701

Edit your method to this:

 // the method from MouseListener we're interested in this time
 @Override
 public void mousePressed( MouseEvent e) {
     this.x = e.getX();
     this.y = e.getY();
     this.repaint();
 }

Your code draws the Jpanel with the square at the default point (150, 150). With the edit. You will change the default (150, 150) to what ever coordinates your mouse is and then tell the JPanel it should repaint itself what will call the paintComponent method that will draw the square at your mouse position.

Upvotes: 1

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