ImagePreview.java

/*
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 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle or the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
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 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

package javademo.swing.dialog.FileChooserDemo2;

import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Image;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import java.io.File;

import javax.swing.ImageIcon;
import javax.swing.JComponent;
import javax.swing.JFileChooser;

/* ImagePreview.java by FileChooserDemo2.java. */
@SuppressWarnings("serial")
public class ImagePreview extends JComponent implements PropertyChangeListener
{
    ImageIcon thumbnail = null;
    
    File file = null;
    
    public ImagePreview(JFileChooser fc)
    {
        setPreferredSize(new Dimension(100, 50));
        fc.addPropertyChangeListener(this);
    }
    
    public void loadImage()
    {
        if (file == null)
        {
            thumbnail = null;
            return;
        }
        
        // Don't use createImageIcon (which is a wrapper for getResource)
        // because the image we're trying to load is probably not one
        // of this program's own resources.
        ImageIcon tmpIcon = new ImageIcon(file.getPath());
        if (tmpIcon != null)
        {
            if (tmpIcon.getIconWidth() > 90)
            {
                thumbnail = new ImageIcon(tmpIcon.getImage().getScaledInstance(90, -1, Image.SCALE_DEFAULT));
            }
            else
            { // no need to miniaturize
                thumbnail = tmpIcon;
            }
        }
    }
    
    public void propertyChange(PropertyChangeEvent e)
    {
        boolean update = false;
        String prop = e.getPropertyName();
        
        // If the directory changed, don't show an image.
        if (JFileChooser.DIRECTORY_CHANGED_PROPERTY.equals(prop))
        {
            file = null;
            update = true;
            
            // If a file became selected, find out which one.
        }
        else if (JFileChooser.SELECTED_FILE_CHANGED_PROPERTY.equals(prop))
        {
            file = (File)e.getNewValue();
            update = true;
        }
        
        // Update the preview accordingly.
        if (update)
        {
            thumbnail = null;
            if (isShowing())
            {
                loadImage();
                repaint();
            }
        }
    }
    
    protected void paintComponent(Graphics g)
    {
        if (thumbnail == null)
        {
            loadImage();
        }
        if (thumbnail != null)
        {
            int x = getWidth() / 2 - thumbnail.getIconWidth() / 2;
            int y = getHeight() / 2 - thumbnail.getIconHeight() / 2;
            
            if (y < 0)
            {
                y = 0;
            }
            
            if (x < 5)
            {
                x = 5;
            }
            thumbnail.paintIcon(this, g, x, y);
        }
    }
}