/*
* This method is called every time:
* - to make sure the viewport is returned to its default position
* - to remove the horizontal scrollbar when it is not wanted
*/
private void checkHorizontalScrollBar(BasicComboPopup popup) {
// Reset the viewport to the left
JViewport viewport = scrollPane.getViewport();
Point p = viewport.getViewPosition();
p.x = 0;
viewport.setViewPosition(p);
// Remove the scrollbar so it is never painted
if (!scrollBarRequired) {
scrollPane.setHorizontalScrollBar(null);
return;
}
// Make sure a horizontal scrollbar exists in the scrollpane
JScrollBar horizontal = scrollPane.getHorizontalScrollBar();
if (horizontal == null) {
horizontal = new JScrollBar(JScrollBar.HORIZONTAL);
scrollPane.setHorizontalScrollBar(horizontal);
scrollPane.setHorizontalScrollBarPolicy(JScrollPane.HORIZONTAL_SCROLLBAR_AS_NEEDED);
}
// Potentially increase height of scroll pane to display the scrollbar
if (horizontalScrollBarWillBeVisible(popup, scrollPane)) {
Dimension scrollPaneSize = scrollPane.getPreferredSize();
scrollPaneSize.height += horizontal.getPreferredSize().height;
scrollPane.setPreferredSize(scrollPaneSize);
scrollPane.setMaximumSize(scrollPaneSize);
scrollPane.revalidate();
}
}
/*
* I can't find any property on the scrollBar to determine if it will be
* displayed or not so use brute force to determine this.
*/
protected int getScrollBarWidth(BasicComboPopup popup, JScrollPane scrollPane) {
int scrollBarWidth = 0;
JComboBox comboBox = (JComboBox) popup.getInvoker();
if (comboBox.getItemCount() > comboBox.getMaximumRowCount()) {
JScrollBar vertical = scrollPane.getVerticalScrollBar();
scrollBarWidth = vertical.getPreferredSize().width;
}
return scrollBarWidth;
}