JScrollPopupMenu.java 文件源码

public JScrollPopupMenu(String label) {
    super(label);
    setLayout(new ScrollPopupMenuLayout());

    super.add(getScrollBar());
    addMouseWheelListener(new MouseWheelListener() {
        @Override
        public void mouseWheelMoved(MouseWheelEvent event) {
            JScrollBar scrollBar = getScrollBar();
            int amount = (event.getScrollType() == MouseWheelEvent.WHEEL_UNIT_SCROLL) ? event.getUnitsToScroll() * scrollBar.getUnitIncrement() : (event.getWheelRotation() < 0 ? -1 : 1) * scrollBar.getBlockIncrement();

            scrollBar.setValue(scrollBar.getValue() + amount);
            event.consume();
        }
    });
}