de.codesourcery.eve.skills.ui.utils.PopupMenuBuilder.java Source code

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Here is the source code for de.codesourcery.eve.skills.ui.utils.PopupMenuBuilder.java

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/**
 * Copyright 2004-2009 Tobias Gierke <tobias.gierke@code-sourcery.de>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package de.codesourcery.eve.skills.ui.utils;

import java.awt.event.ActionEvent;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.util.ArrayList;
import java.util.List;

import javax.swing.AbstractAction;
import javax.swing.Action;
import javax.swing.JComponent;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;

import org.apache.commons.lang.StringUtils;

public class PopupMenuBuilder extends MouseAdapter {

    private final JPopupMenu popupMenu = new JPopupMenu();

    private final List<Object> entries = new ArrayList<Object>();

    public void mousePressed(MouseEvent e) {
        maybeShowPopup(e);
    }

    public void mouseReleased(MouseEvent e) {
        maybeShowPopup(e);
    }

    protected static final Object SEPARATOR = new Object();

    /**
     * A context menu-action that - instead of just
     * not being rendered at all - shows a disabled
     * label that acts as a hint on why this action
     * is currently disabled. 
     *  
     * @author tobias.gierke@code-sourcery.de
     */
    public interface IActionWithDisabledText extends Action {

        /**
         * Returns the label to be rendered
         * while this action is disabled.
         * 
         * @return label for when this action is disabled, <code>null</code>/blank
         * to completely hide the corresponding menu item 
         */
        public String getDisabledText();
    }

    protected static final class MyMenuItem {

        private final String label;
        private final Action action;

        public MyMenuItem(String label, Action action) {
            if (label == null) {
                throw new IllegalArgumentException("label cannot be NULL");
            }
            if (action == null) {
                throw new IllegalArgumentException("action cannot be NULL");
            }
            this.label = label;
            this.action = action;
        }

        public boolean isEnabled() {
            return action.isEnabled();
        }

        public String getLabel() {
            return label;
        }

        public Action getAction() {
            return action;
        }
    }

    public PopupMenuBuilder attach(JComponent comp) {
        comp.addMouseListener(this);
        return this;
    }

    public PopupMenuBuilder detach(JComponent comp) {
        comp.removeMouseListener(this);
        return this;
    }

    public PopupMenuBuilder addItem(String label, final Runnable r) {
        this.entries.add(new MyMenuItem(label, new AbstractAction() {

            @Override
            public boolean isEnabled() {
                return true;
            }

            @Override
            public void actionPerformed(ActionEvent e) {
                r.run();
            }
        }));
        return this;
    }

    public PopupMenuBuilder addItem(String label, Action action) {
        this.entries.add(new MyMenuItem(label, action));
        return this;
    }

    public PopupMenuBuilder addSeparatorIfNotEmpty() {
        if (!entries.isEmpty()) {
            this.entries.add(SEPARATOR);
        }
        return this;
    }

    public PopupMenuBuilder addSeparator() {
        this.entries.add(SEPARATOR);
        return this;
    }

    /**
     * Checks whether a mouse-click event
     * should trigger a context-sensitive popup menu
     * and renders the menu if so.
     * 
     * @param e
     */
    protected void maybeShowPopup(MouseEvent e) {

        if (!e.isPopupTrigger()) {
            return;
        }

        popupMenu.removeAll();

        if (populateMenu() > 0) {
            popupMenu.show(e.getComponent(), e.getX(), e.getY());
        }
    }

    protected int populateMenu() {

        int itemCount = 0;
        for (Object obj : this.entries) {
            if (obj == SEPARATOR) {
                popupMenu.addSeparator();
            } else {
                final MyMenuItem item = (MyMenuItem) obj;

                final Action action = item.getAction();

                final boolean isEnabled = action.isEnabled();

                if (isEnabled || action instanceof IActionWithDisabledText) {
                    final JMenuItem menuItem = new JMenuItem(action);

                    final String text;
                    if (isEnabled) {
                        text = item.getLabel();
                    } else {
                        text = ((IActionWithDisabledText) action).getDisabledText();
                        // do not render action that returns a blank/empty label
                        if (StringUtils.isBlank(text)) {
                            continue;
                        }
                        menuItem.setEnabled(false);
                    }
                    menuItem.setText(text);
                    popupMenu.add(menuItem);
                    itemCount++;
                }
            }
        }
        return itemCount;
    }

}