imagebutton.java

MegaMek is a networked Java clone of BattleTech, a turn-based sci-fi boardgame for 2+ players. Fight

/**
 * MegaMek - Copyright (C) 2004 Ben Mazur ([e-mail])
 * 
 *  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 2 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.
 */
 
package megamek.client.ui.AWT.widget;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.awt.MediaTracker;
import java.awt.Point;
import java.awt.Shape;

/**
 * This class implements buttons that display a <code>java.awt.Image</code>
 * instead of a text label.
 *
 * @author      James Damour
 */
public class ImageButton extends SizedButton {

    /** The image that the button displays.
     */
    private Image image = null;

    /** The dimensions of the image.
     */
    private Dimension imageSize = new Dimension();

    /** The object that makes sure thet the image is fully rendered.
     */
    private MediaTracker tracker = new MediaTracker( this );

    /** The size of the edge of the button.
     */
    public static final int EDGE = 4;

    /**
     * Construct a button that uses an image instead of a text label.
     */
    public ImageButton() {
        super();
    }

    /**
     * Construct a button uses the given image instead of a text label.
     *
     * @param   img - the <code>Image</code> the button displays.
     *          This value may be <code>null</code>.
     */
    public ImageButton( Image img ) {
        super();
        if ( null != img ) setImage( img );
    }

    /**
     * Get the image displayed on this button.
     *
     * @return  the <code>Image</code> that this button displays.
     *          This value may be <code>null</code>.
     */
    public Image getImage() {
        return image;
    }

    /**
     * Set the image displayed on this button.
     * <p/>
     * Please note!!!  Do not call this method within an event handler
     * for the same <code>ImageButton</code> object or the image may not
     * get drawn properly.
     *
     * @param   img - the <code>Image</code> that this button displays.
     *          This value may be <code>null</code>.
     */
    public synchronized void setImage( Image img ) {

        // Save the passed image.
        image = img;

        // We need to repaint ourself.
        repaint();

        // Return if we are clearing the image.
        if ( null == image ) return;

        // Start a tracker to see if the image is fully rendered.
        tracker.addImage( image, 0 );
    }

    /**
     * Paint the image as the base of the button (if we have one).
     * <p/>
     * Overrides <code>java.awt.Component#paint(Graphics).
     *
     * @param   g - the <code>Graphics</code> needing update.
     */
    public void paint( Graphics g ) {

        // Paint the button default.
        super.paint( g );

        // Do we have an image to paint?
        if ( null != image ) {

            try {
                // Render the image when necessary.
                // Resize the button as needed.
                if ( !tracker.checkID( 0 ) ) {
                    tracker.waitForID( 0 );

                    // Get the size of the image.
                    imageSize.width = image.getWidth(this);
                    imageSize.height = image.getHeight(this);

                    // Set the preferred size of this
                    // button to the size of the image.
                    setPreferredSize( imageSize );

                }

                // Get the *actual* size of this button
                // (which may differ from the image size).
                Dimension size = getSize();

                // If the button is larger than the image, center the image.
                Point start = new Point(0, 0);
                if ( size.width > imageSize.width ) {
                    start.x = (size.width - imageSize.width) / 2;
                }
                if ( size.height > imageSize.height ) {
                    start.y = (size.height - imageSize.height) / 2;
                }

                // Make sure that there's room to paint the edge.
                Shape oldClip = g.getClip();
                g.setClip( EDGE, EDGE, size.width-2*EDGE, size.height-2*EDGE );

                // Paint the image.
                g.drawImage( image, start.x, start.y,
                             imageSize.width, imageSize.height, this );
                g.setClip( oldClip );

            } catch ( InterruptedException err ) {
                // Print an error message and clear the image.
                System.err.println( "Could not load image:" ); //$NON-NLS-1$
                System.err.println( err.getMessage() );
                image = null;
            }

        } // End have-image

    }

}