zkoss/zk

/* JPEGEncoder.java

    Purpose:
        
    Description:
        
    History:
        Tue Jun 24 16:16:29     2008, Created by tomyeh

Copyright (C) 2008 Potix Corporation. All Rights Reserved.

{{IS_RIGHT
    This program is distributed under LGPL Version 2.1 in the hope that
    it will be useful, but WITHOUT ANY WARRANTY.
}}IS_RIGHT
*/
package org.zkoss.image.encoder;

import java.io.ByteArrayOutputStream;
import java.awt.image.RenderedImage;
import javax.imageio.IIOImage;
import javax.imageio.ImageIO;
import javax.imageio.ImageWriteParam;
import javax.imageio.ImageWriter;
import javax.imageio.stream.ImageOutputStream;

/**
 * The encoder for encoding an image into the JPEG format
 *
 * @author tomyeh
 * @since 3.0.7
 */
public class JPEGEncoder implements ImageEncoder {
    private float _quality = 0.95f;

    public JPEGEncoder() {
    }

    public byte[] encode(RenderedImage image) throws java.io.IOException {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        ImageWriter iw = ImageIO.getImageWritersByFormatName("jpeg").next();
        ImageWriteParam iwp = iw.getDefaultWriteParam();
        iwp.setCompressionMode(ImageWriteParam.MODE_EXPLICIT);
        iwp.setCompressionQuality(_quality);
        ImageOutputStream ios = ImageIO.createImageOutputStream(os);
        iw.setOutput(ios);
        iw.write(null, new IIOImage(image, null, null), iwp);
        ios.flush();
        iw.dispose();
        ios.close();
        return os.toByteArray();
    }
    /** Returns the quality of the image encoding.
     * It is a number between 0 and 1. The higher the value,
     * the better the output quality.
     *
     * <p>Default: 0.95f.
     */
    public float getQuality() {
        return _quality;
    }
    public void setQuality(float quality) {
        if (quality < 0.0f || quality > 1.0f)
            throw new IllegalArgumentException("out of range: "+quality);
        _quality = quality;
    }
    public boolean isEncodingAlpha() {
        return false;
    }
    public void setEncodingAlpha(boolean encodeAlpha) {
    }
}