package org.geogebra.desktop.gui.inputbar;

import javax.swing.JComboBox;
import javax.swing.event.PopupMenuEvent;
import javax.swing.event.PopupMenuListener;

/**
 * JComboBox that allows using setPrototypeDisplayValue() while keeping the
 * correct (usually larger) width of its popup menu.
 * 
 * @author Markus Hohenwarter
 * @see "http://forums.sun.com/thread.jspa?threadID=570675"
 */
public class MyComboBox extends JComboBox implements PopupMenuListener {

	private static final long serialVersionUID = 1L;

	private int popupWidth = 400;

	public MyComboBox() {
		addPopupMenuListener(this);
	}

	/**
	 * Call this method after you have filled this combo box in order to keep
	 * the correct width of the popup menu.
	 */
	public void setPrototypeDisplayValue(String str) {
		popupWidth = getPreferredSize().width + 10;
		super.setPrototypeDisplayValue(str);
	}

	// Popup state to prevent loop
	boolean stateCmb = false;

	// Extend JComboBox's length and reset it
	@Override
	public void popupMenuWillBecomeVisible(PopupMenuEvent e) {
		JComboBox cmb = (JComboBox) e.getSource();
		int oldWidth = cmb.getPreferredSize().width;

		// Extend JComboBox
		cmb.setSize(popupWidth, cmb.getHeight());

		// If it pops up now JPopupMenu will still be short
		// Fire popupMenuCanceled...
		if (!stateCmb) {
			cmb.firePopupMenuCanceled();
		}

		// Reset JComboBox and state
		stateCmb = false;
		cmb.setSize(oldWidth, cmb.getHeight());
	}

	// Show extended JPopupMenu
	@Override
	public void popupMenuCanceled(PopupMenuEvent e) {
		JComboBox cmb = (JComboBox) e.getSource();
		stateCmb = true;
		// JPopupMenu is long now, so repop
		cmb.showPopup();
	}

	@Override
	public void popupMenuWillBecomeInvisible(PopupMenuEvent e) {
		stateCmb = false;
	}
}