JTextPane prevents scrolling in the parent JScrollPane

Question

I have the following \"tree\" of objects:

JPanel
    JScrollPane
        JPanel
            JPanel
                JScrollPane
                    JTextPane
         


        

Answer 1

Inspired by the existing answers, I

• took the code from Nemi's answer
• combined it with kleopatra's answer to a similar question to avoid constructing the MouseWheelEvent verbosely
• extracted the listener into its own top-level class so that it can be used in contexts where the JScrollPane class cannot be extended
• inlined the code as far as possible.

The result is this piece of code:

import java.awt.Component;
import java.awt.event.MouseEvent;
import java.awt.event.MouseWheelEvent;
import java.awt.event.MouseWheelListener;
import javax.swing.JScrollBar;
import javax.swing.JScrollPane;
import javax.swing.SwingUtilities;

/**
 * Passes mouse wheel events to the parent component if this component
 * cannot scroll further in the given direction.
 * 

 * This behavior is a little better than Swing's default behavior but
 * still worse than the behavior of Google Chrome, which remembers the
 * currently scrolling component and sticks to it until a timeout happens.
 *
 * @see Stack Overflow
 */
public final class MouseWheelScrollListener implements MouseWheelListener {

    private final JScrollPane pane;
    private int previousValue;

    public MouseWheelScrollListener(JScrollPane pane) {
        this.pane = pane;
        previousValue = pane.getVerticalScrollBar().getValue();
    }

    public void mouseWheelMoved(MouseWheelEvent e) {
        Component parent = pane.getParent();
        while (!(parent instanceof JScrollPane)) {
            if (parent == null) {
                return;
            }
            parent = parent.getParent();
        }

        JScrollBar bar = pane.getVerticalScrollBar();
        int limit = e.getWheelRotation() < 0 ? 0 : bar.getMaximum() - bar.getVisibleAmount();
        if (previousValue == limit && bar.getValue() == limit) {
            parent.dispatchEvent(SwingUtilities.convertMouseEvent(pane, e, parent));
        }
        previousValue = bar.getValue();
    }
}

It is used like this:

JScrollPane pane = new JScrollPane();
pane.addMouseWheelListener(new MouseWheelScrollListener(pane));

Once an instance of this class is created and bound to a scroll pane, it cannot be reused for another component since it remembers the previous position of the vertical scroll bar.