Swing: JScrollPane causing render issues

Question

Sometimes (not always) when scrolling the bar of my JScrollPane, some of the components (usually the text ones like JLabels) don't repaint properly and they end up only being partially rendered.

I don't know why this is. I've tried invoking paint() inside of an AdjustmentListener, but that doesn't seem to help.

Any ideas?

EDIT: Initialization of the components

    panel = new JPanel();
    ImageIcon img = new ImageIcon("editor.png");
    setIconImage(img.getImage());
    initComponents();

    final JScrollPane pane = new JScrollPane(panel);
    this.setContentPane(pane);
    //pane.setLayout(new ScrollPaneLayout());
    //pane.setVerticalScrollBarPolicy(JScrollPane.VERTICAL_SCROLLBAR_ALWAYS);
    Dimension dim = panel.getSize();
    dim.height = dim.height - 100;
    pane.setSize(dim);
    this.setSize(dim);
    AdjustmentListener hListener = new AdjustmentListener() {
        @Override
        public void adjustmentValueChanged(AdjustmentEvent e) {
            repaint();
            for(Component c : panel.getComponents())
                c.repaint();
            for(Component c : pane.getComponents())
                c.repaint();
            panel.repaint();
            panel.revalidate();
            pane.repaint();
            pane.revalidate();
        }
    };
    pane.getVerticalScrollBar().addAdjustmentListener(hListener);
    panel.setVisible(true);
    pane.setVisible(true);

The posted code does not reproduce the problem, and nor can I see it suggesting the cause of the problem. Consider creating and posting an [sscce](http://sscce.org). — Hovercraft Full Of Eels, Jul 09 '12 at 03:45
Well I'm not really sure what to do, I don't want to post my entire initcomponents(), it'll be way too big. Besides what I've posted, I just initiate the components and add them to 'panel' — Blackvein, Jul 09 '12 at 03:47
And we don't want to see your entire code either. Consider cutting back on your code until you have isolated the problem. — Hovercraft Full Of Eels, Jul 09 '12 at 03:49

score 8 · Answer 1 · edited May 23 '17 at 12:33

Violations of any of these basic principles can cause rendering artifact.

Verify that Swing GUI objects are constructed and manipulated only on the event dispatch thread.
Ensure that you honor the opacity property. In particular, JLabel is not opaque by default.
"Swing programs should override paintComponent() instead of overriding paint()."—Painting in AWT and Swing: The Paint Methods.

Addendum: Incorporating these dicta, this related example scrolls thousands of flashing JLabel instances without artifact.

Swing: JScrollPane causing render issues

1 Answers1

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