imagepanel.java

一个用于排队系统仿真的开源软件,有非常形象的图象仿真过程!

/**    
  * Copyright (C) 2006, Laboratorio di Valutazione delle Prestazioni - Politecnico di Milano

  * 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.

  * You should have received a copy of the GNU General Public License
  * along with this program; if not, write to the Free Software
  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
  */
  
package jmt.gui.common.panels;

import javax.swing.*;
import java.awt.*;
import java.awt.event.ComponentAdapter;
import java.awt.event.ComponentEvent;
import java.util.HashMap;

/**
 * <p>Title: ImagePanel</p>
 * <p>Description: A graphical component used to swow a given IconImage. This panel is designed to
 * auto-resize the image basing on width assigned by layout managers, mantaining aspect ratio.
 * A maximum height can be specified too. Internal caching is used as long as width is not changed
 * to avoid to recalculate images scaling continously.</p>
 * 
 * @author Bertoli Marco
 *         Date: 1-lug-2005
 *         Time: 15.55.21
 */
public class ImagePanel extends JLabel{
    protected ImageIcon image;
    protected int maxheight = Integer.MAX_VALUE;
    protected int currentWidth;
    protected HashMap cache = new HashMap();
    /**
     * Construct a new ImagePanel
     */
    public ImagePanel() {
        super();
        this.setHorizontalAlignment(JLabel.CENTER);
        this.addComponentListener(new ComponentAdapter() {
            public void componentResized(ComponentEvent e) {
                if (image != null)
                    ImagePanel.this.resizeImage();
            }
        });
    }

    /**
     * Sets image to be shown on this panel
     * @param image image to be shown in IconImage format
     */
    public void setImage(ImageIcon image) {
        this.image = image;
        resizeImage();
    }

    /**
     * Sets maximum height allowed for this component
     * @param height maximum height allowed
     */
    public void setMaximumHeight(int height) {
        this.maxheight = height;
        cache = new HashMap();
        if (image != null)
            resizeImage();
    }

    /**
     * Helper method used to resize input image and display it. If image was already resized to current size, 
     * take the copy from local cache.
     */
    protected void resizeImage() {
        // Resets cache if width has changed
        if (currentWidth != this.getWidth()) {
            currentWidth = this.getWidth();
            cache = new HashMap();
        }

        // If this component size is not already defined, sets image without resizing
        Dimension d = this.getSize();
        if (d.width <= 0 || d.height <= 0) {
            this.setIcon(image);
            return;
        }

        // If cache contains image of the correct size, returns it.
        if (cache.containsKey(image)) {
            this.setIcon((ImageIcon)cache.get(image));
            return;
        }

        // Calculates ratio factor
        Image tmp = image.getImage();
        float scale = (float)d.width / (float)image.getIconWidth();

        if (scale * image.getIconHeight() > maxheight)
            scale = (float)maxheight / (float)image.getIconHeight();

        // Resizes image
        tmp = tmp.getScaledInstance((int) (scale * image.getIconWidth()),
                    (int) (scale * image.getIconHeight()),
                    Image.SCALE_SMOOTH);
        ImageIcon resized = new ImageIcon(tmp);
        cache.put(image, resized);
        this.setIcon(resized);
    }
}