ImageJ zoom doesn't refresh the image

Question

The following code below shows when an image is opened, the user should be able to zoom in and out of the image using the arrow keys. But when I zoom I get the following picture:

I hope someone can see where I am going wrong cause when I move the frame (kind of like refreshing), then the picture is okay but if you don't move it and then this is what you see. I want to fix this so even if you don't move the frame the picture is still okay. Thanks in advance.

Here is the main class where it contains a call to the imageJ zoom class:

    zoom = new JMenu("Zoom");
    zoom.setEnabled(false);

    JMenuItem in = new JMenuItem("Zoom In");
    in.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_UP, ActionEvent.ALT_MASK));
    in.addActionListener(new ActionListener(){

        @Override
        public void actionPerformed(ActionEvent arg0) {
            // TODO Auto-generated method stub

            MyInternalFrame selectedFrame = (MyInternalFrame) desktop.getSelectedFrame();
            Zoom z = new Zoom(selectedFrame.getImage());
            String args = "in";
            z.run(args);
        }

    });

    JMenuItem out = new JMenuItem("Zoom Out");
    out.setAccelerator(KeyStroke.getKeyStroke(KeyEvent.VK_DOWN, ActionEvent.ALT_MASK));
    out.addActionListener(new ActionListener(){

        @Override
        public void actionPerformed(ActionEvent arg0) {
            // TODO Auto-generated method stub
            MyInternalFrame selectedFrame = (MyInternalFrame) desktop.getSelectedFrame();
            Zoom z = new Zoom(selectedFrame.getImage());
            String args = "out";
            z.run(args);
        }

    });

    zoom.add(in);
    zoom.add(out);

I also had to add a constructor to the zoom so it would take the image my customized GUI opens (this is in the zoom class):

    ImagePlus imp;
public Zoom (ImagePlus img){
    imp = img;
}

In the custom window class, where the image is opened, I have a component listener which resizes the image to fit the frame size and works very well (I don't know if this is the problem):

            @Override
    public void componentResized(ComponentEvent arg0) {
        // TODO Auto-generated method stub
        Rectangle rect = desktop.getSelectedFrame().getBounds();
        MyInternalFrame f = (MyInternalFrame) desktop.getSelectedFrame();
        f.getImage().getCanvas().fitToWindow(rect);
        System.out.println("resized- the real one");
    }

In the same class here is where the image is added to the frame:

           JPanel panel = new JPanel();

        ImageCanvas c = new ImageCanvas(image);
        c.getImage();

        //panel2.add(new JLabel(new ImageIcon(c.getImage())));
         m = new ImageWindow(image);

        Image n = new Image();
        //frame = new MyInternalFrame(title, img, save,m);
        //ImageCanvas c = m.getCanvas();
        ImagePlus im = new ImagePlus();
        im.setImage(image);

        String [] array = title.split("/");
        //System.out.println("in manager: "+array[5]);
        //image.setTitle(path);
        frame = new MyInternalFrame(image.getTitle(), image, save, title);

        m.centerNextImage();
        //image.getCanvas().setScaleToFit(true);

        panel.add(m.getCanvas());
        panel.setBackground(Color.white);
        frame.add(panel);
        frames.add(frame);

        frame.setVisible(true); 
        frame.setAutoscrolls(true);
        frame.setAutoscrolls(true);
        //frame.setOpaque(true);
        frame.setResizable(true);
        desktop.add(frame);

Answer 1

I don't get the background of how you define the class MyInternalFrame and the ImageCanvas.

I suggest you to check the code :

f.getImage().getCanvas().fitToWindow(rect);

To resize a image on a panel or other component:

step1: you can override the paintComponent() method,and use the graphics object's scale() and translate() method to resize the image.

step2: call the panel's repaint() method to update the panel.

This will really work.