Thumbnail.java

package edu.mbl.jif.imaging;

import java.awt.Image;
import java.awt.Graphics2D;
import java.awt.geom.AffineTransform;
import java.awt.image.BufferedImage;
import java.io.IOException;
import java.io.OutputStream;
import java.io.FileOutputStream;
import javax.swing.ImageIcon;
//import com.sun.image.codec.jpeg.JPEGCodec;
//import com.sun.image.codec.jpeg.JPEGImageEncoder;

public class Thumbnail {

   /**
    * Reads an image in a file and creates a thumbnail in another file.
    *
    * @param orig The name of image file.
    * @param thumb The name of thumbnail file. Will be created if necessary.
    * @param maxDim The width and height of the thumbnail must be maxDim pixels or less.
    */
   public static void createThumbnail(
           String orig, String thumb, int maxDim) {
      try {
         // Get the image from a file.
         Image inImage = new ImageIcon(orig).getImage();

         // Determine the scale.
         double scale = (double) maxDim / (double) inImage.getHeight(null);
         if (inImage.getWidth(null) > inImage.getHeight(null)) {
            scale = (double) maxDim / (double) inImage.getWidth(null);
         }

         // Determine size of new image.
         //One of them
         // should equal maxDim.
         int scaledW = (int) (scale * inImage.getWidth(null));
         int scaledH = (int) (scale * inImage.getHeight(null));

         // Create an image buffer in
         //which to paint on.
         BufferedImage outImage =
                 new BufferedImage(scaledW, scaledH,
                 BufferedImage.TYPE_INT_RGB);

         // Set the scale.
         AffineTransform tx = new AffineTransform();

         // If the image is smaller than
         //the desired image size,
         // don't bother scaling.
         if (scale < 1.0d) {
            tx.scale(scale, scale);
         }

         // Paint image.
         Graphics2D g2d = outImage.createGraphics();
         g2d.drawImage(inImage, tx, null);
         g2d.dispose();

         // JPEG-encode the image
         //and write to file.
         OutputStream os = new FileOutputStream(thumb);
         // TODO JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(os);
         //encoder.encode(outImage);
         os.close();
      } catch (IOException e) {
         e.printStackTrace();
      }
   }
}