PopupMenuHandler.java

/*
 * Copyright (C) 2010 Brockmann Consult GmbH (info@brockmann-consult.de)
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License as published by the Free
 * Software Foundation; either version 3 of the License, or (at your option)
 * any later version.
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, see http://www.gnu.org/licenses/
 */

package org.esa.snap.ui;

import org.esa.snap.core.util.Guardian;

import javax.swing.AbstractButton;
import javax.swing.Action;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.JSeparator;
import java.awt.Component;
import java.awt.event.KeyEvent;
import java.awt.event.KeyListener;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.Arrays;

/**
 * A handler which can be registered on components as a mouse listener.
 * <p>This handler pops-up a popup menu if the corresponding event is a popup menu trigger on a given platform. The
 * popup-menu is created by the <code>PopupMenuFactory</code> instance passed to the constructor of this class.
 *
 * @author Norman Fomferra
 * @see PopupMenuFactory
 */
public class PopupMenuHandler implements MouseListener, KeyListener {

    private PopupMenuFactory popupMenuFactory;

    /**
     * Constructs a new pop-up menu handler for th given pop-up menu factory.
     *
     * @param popupMenuFactory the factory for the menu, must not be <code>null</code>
     */
    public PopupMenuHandler(PopupMenuFactory popupMenuFactory) {
        Guardian.assertNotNull("popupMenuFactory", popupMenuFactory);
        this.popupMenuFactory = popupMenuFactory;
    }

    /**
     * Invoked when the mouse has been clicked on a component.
     */
    public void mouseClicked(MouseEvent event) {
        maybeShowPopupMenu(event);
    }

    /**
     * Invoked when a mouse button has been pressed on a component.
     */
    public void mousePressed(MouseEvent event) {
        maybeShowPopupMenu(event);
    }

    /**
     * Invoked when a mouse button has been released on a component.
     */
    public void mouseReleased(MouseEvent event) {
        maybeShowPopupMenu(event);
    }

    /**
     * Invoked when the mouse enters a component.
     */
    public void mouseEntered(MouseEvent event) {
    }

    /**
     * Invoked when the mouse exits a component.
     */
    public void mouseExited(MouseEvent event) {
    }

    /**
     * Invoked when a key has been pressed.
     */
    public void keyPressed(KeyEvent event) {
    }

    /**
     * Invoked when a key has been released.
     */
    public void keyReleased(KeyEvent event) {
    }

    /**
     * Invoked when a key has been typed. This event occurs when a key press is followed by a key release.
     */
    public void keyTyped(KeyEvent event) {
    }

    private void maybeShowPopupMenu(MouseEvent event) {
        if (event.isPopupTrigger()) {
            if (event.getComponent().isVisible()) {
                showPopupMenu(event);
            }
        }
    }

    private void showPopupMenu(MouseEvent event) {
        JPopupMenu popupMenu = popupMenuFactory.createPopupMenu(event.getComponent());
        if (popupMenu == null) {
            popupMenu = popupMenuFactory.createPopupMenu(event);
        }
        if (popupMenu != null) {
            rearrangeMenuItems(popupMenu);
            UIUtils.showPopup(popupMenu, event);
        }
    }

    private void rearrangeMenuItems(JPopupMenu popupMenu) {
        Component[] components = popupMenu.getComponents();
        Arrays.sort(components, (o1, o2) -> getGroupName(o1).compareToIgnoreCase(getGroupName(o2)));
        popupMenu.removeAll();
        Component lastComponent = null;
        String lastGroupName = null;
        for (Component component : components) {
            String groupName = getGroupName(component);
            if (lastGroupName != null
                    && !lastGroupName.equals(groupName)
                    && !(lastComponent instanceof JSeparator)) {
                popupMenu.addSeparator();
            }
            lastGroupName = groupName;
            lastComponent = component;
            if (component instanceof JMenuItem) {
                popupMenu.add((JMenuItem) component);
            } else if (component instanceof Action) {
                popupMenu.add((Action) component);
            } else {
                popupMenu.add(component);
            }
        }
    }

    private String getGroupName(Component component) {
        Action action = null;
        if (component instanceof AbstractButton) {
            action = ((AbstractButton) component).getAction();
        } else if (component instanceof Action) {
            action = (Action) component;
        }
        if (action != null) {
            Object parent = action.getValue("parent");
            if (parent != null) {
                return parent.toString();
            }
        }
        return "";
    }
}