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Thread: My MouseInputListener methods aren't being called.

  1. #1
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    Exclamation My MouseInputListener methods aren't being called.

    I have the following class which uses mousePressed, mouseDragged, and mouseReleased. I've thrown some breakpoints in these methods with jdb, but I find that they aren't triggered when I try and click on my canvas. I've been working on this for a few hours and can't figure out why. Could someone offer a second set of eyes?

    Thanks,
    import java.awt.BasicStroke;
    import java.awt.Graphics2D;
    import java.awt.Point;
    import java.awt.event.MouseEvent;
    import java.awt.geom.Rectangle2D;
    import java.awt.image.BufferedImage;
    import javax.swing.ImageIcon;
    import javax.swing.JLabel;
    import javax.swing.JPanel;
    import javax.swing.event.MouseInputListener;
     
    class Canvas extends JPanel implements MouseInputListener {
      private BufferedImage m_img;
      private Point m_refPoint;
      private JLabel m_container;
     
      public Canvas() {
        m_img = new BufferedImage(500, 500, BufferedImage.TYPE_INT_RGB);
        m_refPoint = null;
        m_container = new JLabel(new ImageIcon());
        m_container.setIcon(new ImageIcon(m_img));
        m_container.addMouseListener(this);
        m_container.addMouseMotionListener(this);
      }
     
      protected void draw(Point end, BufferedImage img) {
        Graphics2D g2 = img.createGraphics();
        g2.setPaint( m_selector.getFg() );
        g2.setStroke( new BasicStroke(2.0f) );
     
        g2.draw(new Rectangle2D.Float((float)m_refPoint.x,
                                      (float)m_refPoint.y, 
                                      (float)Math.abs(end.x-m_refPoint.x),
                                      (float)Math.abs(end.y-m_refPoint.y)));
     
        m_container.setIcon(new ImageIcon(img));
        repaint();
      }
     
      public void mousePressed(MouseEvent e) {
        m_refPoint = e.getPoint();
      }
     
      public void mouseDragged(MouseEvent e) {
        if (m_refPoint == null) return;
     
        Point end             = e.getPoint();
        BufferedImage scratch = new BufferedImage(m_img.getColorModel(),
                                m_img.copyData(null), 
                                m_img.getColorModel().isAlphaPremultiplied(),
                                null);
        draw( end, scratch );
      }
     
      public void mouseReleased(MouseEvent e) {
        if (m_refPoint == null) return;
        draw( e.getPoint(), m_img);
      }
     
      public void mouseClicked(MouseEvent e) {}
      public void mouseEntered(MouseEvent e) {}
      public void mouseExited (MouseEvent e) {}
      public void mouseMoved  (MouseEvent e) {}
    }


  2. #2
    Super Moderator Norm's Avatar
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    Default Re: My MouseInputListener methods aren't being called.

    Where is the component with the listeners added to the GUI container?
    If you don't understand my answer, don't ignore it, ask a question.

  3. #3
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    Default Re: My MouseInputListener methods aren't being called.

    The component with listeners is "JLabel m_container" which is a member of Canvas and holds an ImageIcon().

    I use these so that when I use the mouse in the container, my methods are called:
    m_container.addMouseListener(this);
    m_container.addMouseMotionListener(this);



    I think my problem is the sizing of the JLabel. I've tried setting m_container.setBackground(Color.BLACK); and everything is still the default colour. When I've loaded BufferedImages from files, JLabel get's resized properly, so I think the problem is in how I've created the BufferedImage.

    I HATE layout managers, for 8 weeks now, these have been the most time consuming parts of my java course. I'm tempted to use a null layout manager and give up on scaling.

    --- Update ---

    Nevermind, I forgot:
    this.add(m_container);

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