HyperlinkLabel.java

/*
 *  UFO Saved Game Editor
 *  Copyright (C) 2010 Christopher Davoren
 * 
 *  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 net.rubikscomplex.ufosge.gui;

import java.awt.Color;
import java.awt.Cursor;
import java.awt.Graphics;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.awt.geom.Rectangle2D;
import java.util.LinkedList;
import javax.swing.JLabel;


/**
 * Implements a JLabel that contains a clickable hyperlink.
 *
 * Code taken from the Sun forums:
 * http://forums.sun.com/thread.jspa?threadID=613854
 * 
 * @author Chris Davoren
 */
public class HyperlinkLabel extends JLabel {

    protected final Color LINK_COLOR = Color.blue;
    protected LinkedList<ActionListener> actionListenerList = new LinkedList<ActionListener>();
    protected boolean underline;
    protected String actionCommand;

    protected MouseListener mouseListener = new MouseAdapter() {

        @Override
        public void mouseEntered(MouseEvent me) {
            underline = true;
            repaint();
        }

        @Override
        public void mouseExited(MouseEvent me) {
            underline = false;
            repaint();
        }

        @Override
        public void mouseClicked(MouseEvent me) {
            fireActionEvent();
        }
    };

    public HyperlinkLabel() {
        this("");
    }

    public HyperlinkLabel(String text) {
        super(text);

        setCursor(Cursor.getPredefinedCursor(Cursor.HAND_CURSOR));
        setForeground(LINK_COLOR);
        addMouseListener(mouseListener);
        setActionCommand(text);
    }

    public void setActionCommand(String command) {
        actionCommand = command;
    }

    public void addActionListener(ActionListener l) {
        if (!actionListenerList.contains(l)) {
            actionListenerList.add(l);
        }
    }

    public void removeActionListener(ActionListener l) {
        actionListenerList.remove(l);
    }

    protected void fireActionEvent() {
        ActionEvent e = new ActionEvent(this, ActionEvent.ACTION_PERFORMED, actionCommand);
        for (ActionListener l : actionListenerList) {
            l.actionPerformed(e);
        }
    }

    @Override
    public void paint(Graphics g) {
        super.paint(g);
        if (underline) {
            // really all this size stuff below only needs to be recalculated if font or text changes
            Rectangle2D textBounds = getFontMetrics(getFont()).getStringBounds(getText(), g);

            //this layout stuff assumes the icon is to the left, or null
            int y = getHeight() / 2 + (int) (textBounds.getHeight() / 2);
            int w = (int) textBounds.getWidth();
            int x = getIcon() == null ? 0 : getIcon().getIconWidth() + getIconTextGap();

            g.setColor(getForeground());
            g.drawLine(0, y, x + w, y);
        }
    }
}