jpegcodec.java

java1.6众多例子参考

/*
 * @(#)JPEGCodec.java	1.9 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

/**********************************************************************
 **********************************************************************
 **********************************************************************
 *** COPYRIGHT (c) 1997-1998 Eastman Kodak Company.                 ***
 *** As  an unpublished  work pursuant to Title 17 of the United    ***
 *** States Code.  All rights reserved.                             ***
 **********************************************************************
 **********************************************************************
 **********************************************************************/

package com.sun.image.codec.jpeg;

import sun.awt.image.codec.JPEGImageDecoderImpl;
import sun.awt.image.codec.JPEGImageEncoderImpl;
import sun.awt.image.codec.JPEGParam;
import java.awt.image.BufferedImage;
import java.awt.image.Raster;
import java.awt.image.ColorModel;
import java.io.InputStream;
import java.io.OutputStream;

/**
 * This class is a factory for implementations of the JPEG Image
 * Decoder/Encoder.
 * <p>
 * Note that the classes in the com.sun.image.codec.jpeg package are not
 * part of the core Java APIs.  They are a part of Sun's JDK and JRE
 * distributions.  Although other licensees may choose to distribute these
 * classes, developers cannot depend on their availability in non-Sun
 * implementations.  We expect that equivalent functionality will eventually
 * be available in a core API or standard extension.
 * <p>
 *
 * @see JPEGImageDecoder
 * @see JPEGImageEncoder
 */
public class JPEGCodec {
	private JPEGCodec() { }

	/**
	 * This creates an instance of a JPEGImageDecoder that can be used
	 * to decode JPEG Data streams.
	 */
	public static JPEGImageDecoder createJPEGDecoder(InputStream src) {
		return new JPEGImageDecoderImpl(src);
	}

	/**
	 * This creates an instance of a JPEGImageDecoder that can be used
	 * to decode JPEG Data streams.
	 */
	public static JPEGImageDecoder createJPEGDecoder(InputStream src,
													 JPEGDecodeParam jdp) {
		return new JPEGImageDecoderImpl(src, jdp);
	}

	/**
	 * This creates an instance of a JPEGImageEncoder that can be used
	 * to encode image data as JPEG Data streams.
	 */
	public static JPEGImageEncoder createJPEGEncoder(OutputStream dest) {
		return new JPEGImageEncoderImpl(dest);
	}
	/**
	 * This creates an instance of a JPEGImageEncoder that can be used
	 * to encode image data as JPEG Data streams.
	 */
	public static JPEGImageEncoder createJPEGEncoder(OutputStream dest,
													 JPEGEncodeParam jep) {
		return new JPEGImageEncoderImpl(dest, jep);
	}

	/**
	  * This is a factory method for creating JPEGEncodeParam objects.
	  * The returned object should do a credible job of encoding the
	  * given BufferedImage.
	  * @param bi A BufferedImage that is similar to the BufferedImage(s)
	  * that will encoded using the returned JPEGEncodeParam object.
	  */
	public static JPEGEncodeParam getDefaultJPEGEncodeParam(BufferedImage bi)
	{
  	int colorID = JPEGParam.getDefaultColorId(bi.getColorModel());
  	return getDefaultJPEGEncodeParam(bi.getRaster(), colorID);
	}

	/**
	  * This is a factory method for creating JPEGEncodeParam objects.
	  * It is the users responsiblity to match the colorID with the
	  * data contained in the Raster.  Failure to do so may lead to
	  * either poor compression or poor image quality.  If you don't
	  * understand much about JPEG it is strongly recommended that you
	  * stick to the BufferedImage interface.
	  * @param ras Raster that is similar to those to be encoded later.
	  * @param colorID the COLOR_ID for the encoded data.  This should
	  *        match the data in the raster.
	  */
	public static JPEGEncodeParam getDefaultJPEGEncodeParam(Raster ras,
                                                        	int colorID)
	{
  	JPEGParam ret = new JPEGParam(colorID, ras.getNumBands());
  	ret.setWidth(ras.getWidth());
  	ret.setHeight(ras.getHeight());
	
  	return ret;
	}

	/**
	  * This is a factory method for creating JPEGEncodeParam objects.  It
	  * is the users responsiblity to match the colorID with the given
	  * number of bands, which should match the data being encoded.
	  * Failure to do so may lead to poor compression and/or poor image
	  * quality.  If you don't understand much about JPEG it is strongly
	  * recommended that you stick to the BufferedImage interface.
	  *
	  * This can also be used as a factory for a JPEGDecodeParam object.
	  * However this usage is extremely rare, as one needs to be decoding
	  * abbreviated JPEG streams where the JPEG tables are coming from
	  * some source other than a JPEG tables only stream.
	  *
	  * @param numBands the number of bands that will be encoded (max of four).
	  * @param colorID the COLOR_ID for the encoded data.  This is used to
	  * set reasonable defaults in the parameter object.  This must match
	  * the number of bands given.
	  */
	public static JPEGEncodeParam getDefaultJPEGEncodeParam(int numBands,
                                                                int colorID)
            throws ImageFormatException
	{
  	return new JPEGParam(colorID, numBands);
	}

	/**
	 * This is a factory method for creating a JPEGEncodeParam from a
	 * JPEGDecodeParam.  This will return a new JPEGEncodeParam object
	 * that is initialized from the JPEGDecodeParam object.  All major
	 * pieces of information will be initialized from the DecodeParam
	 * (Markers, Tables, mappings).
	 * @param jdp The JPEGDecodeParam object to copy.
	 */

	public static JPEGEncodeParam getDefaultJPEGEncodeParam(JPEGDecodeParam jdp)
	    throws ImageFormatException {
	    return new JPEGParam(jdp);
	}
}