jpegencodeparam.java

java1.6众多例子参考

/*
 * @(#)JPEGEncodeParam.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 *** As  an unpublished  work pursuant to Title 17 of the United    ***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;


/** 
 * JPEGEncodeParam encapsulates tables and options necessary to
 * control encoding of JPEG data streams.  Parameters are either set
 * explicitly by the application for encoding, or read from another
 * JPEG header.<p>

 * When working with BufferedImages, the codec will attempt to match
 * the encoded JPEG COLOR_ID with the ColorModel in the BufferedImage.
 * This is not always possible (the default mappings are listed
 * below).  In cases where unsupported conversions are required (or
 * odd image colorspaces are in use) the user must either convert the
 * image data to a known ColorSpace or encode the data from a raster.
 * When encoding rasters no colorspace adjustments are made, so the
 * user must do any conversions required to get to the encoded
 * COLOR_ID.
 
 * The COLOR_ID for the encoded images is used to control the JPEG
 * codec's inital values for Huffman and Quantization Tables as well
 * as subsampling factors. It is also used to determine what color
 * conversion should be performed to obtain the best encoding.<p>

 * Note: The color ids described herein are simply enumerated values
 * that influence data processing by the JPEG codec.  JPEG compression
 * is, by definition, color blind.  These values are used as hints when
 * compressing JPEG data.  Through these values the JPEG codec can
 * perform some default rotation of data into spaces that will aid in
 * getting better compression ratios.<P>

 * Example behaviour is described below.  Since these mappings are
 * likely to change in the future it is strongly recommended that you
 * make use of the @see JPEGImageEncoder.getDefaultParamBlock calls
 * and check the encodedColorID for your particular BufferedImage.

 * In extreme cases is may be necessary for the user to convert the
 * image to the desired colorspace, and encode it from a Raster.  In
 * this case the API programmer must specify the colorID of the data
 * in the Raster and no color conversion will take place.
 <pre>
 ENCODING:
 
 BufferedImage Type/Instance        JPEG (Encoded) Color ID
 ========================       =======================
 TYPE_GRAY                      COLOR_ID_GRAYSCALE
 TYPE_RGB                       COLOR_ID_YCbCr
 TYPE_YCbCr                     COLOR_ID_YCbCr
 TYPE_YCbCr/CS_PYCC             COLOR_ID_PYCC
 TYPE_CMYK                      COLOR_ID_CMYK
 TYPE_RGB   (w/ alpha)          COLOR_ID_YCbCrA
 TYPE_YCbCr (w/ alpha)          COLOR_ID_YCbCrA
 TYPE_YCbCr/CS_PYCC (w/ alpha)  COLOR_ID_PYCCA
 ** Any Other **                COLOR_ID_UNKNOWN
 </pre> 

 * When the user wants more control than the BufferedImage conversions
 * provide, the user must encode the data from a Raster. In this case
 * the data undergoes no color conversion at all. It is the user's
 * responsiblity to perform the desired conversions.<P>
 
 * If you intend to write a JFIF image (by including the APP0_MARKER)
 * the encoded COLOR_ID must be one of: COLOR_ID_UNKNOWN,
 * COLOR_ID_GRAYSCALE, COLOR_ID_YCbCr, or COLOR_ID_CMYK. In all other
 * instances an ImageformatException will be thrown.<P>

 * <B>IMPORTANT:</B> an Alpha RGB BufferedImage will not map to a
 * valid JFIF stream, you must strip off the alpha prior to encoding
 * if you want a JFIF file.  If the APP0 marker is set and you do not
 * strip off the Alpha, an ImageFormatException will be thrown.
 * <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>
 */

public interface JPEGEncodeParam 
	extends Cloneable, JPEGDecodeParam 
{
	public Object clone();

	/**
	 * Set the horizontal subsample factor for the given component.
	 * Note that the subsample factor is the number of input pixels
	 * that contribute to each output pixel (ussually 2 for YCC).
	 * @param component The component being specified.
	 * @param subsample The subsampling factor being specified.
	 */
	public void setHorizontalSubsampling(int component, 
										 int subsample);
	
	/**
	 * Set the vertical subsample factor for the given component.  Note that
	 * the subsample factor is the number of input pixels that
	 * contribute to each output pixel (ussually 2 for YCC).
	 * @param component The component being specified.
	 * @param subsample The subsampling factor being specified.
	 */
	public void setVerticalSubsampling(int component, 
									   int subsample);
	
	/** 
	 * Sets the coefficient quantization tables at index
	 * passed. tableNum must range in value from 0 - 3.
	 * @param qtable that will be used.
	 * @param tableNum the index of the table to be set.
	 */	
	public void	setQTable( int tableNum, JPEGQTable qTable );

	/** Sets the DC Huffman coding table at index to the table provided. 
	 * @param huffTable JPEGHuffmanTable that will be assigned
	 * to index tableNum.
	 * @param tableNum - the index of the table to be set.
	 * @exception IllegalArgumentException - thrown if the tableNum
	 * is out of range.  Index must range in value from 0 - 3.
	 */		
	public void	setDCHuffmanTable( int tableNum, 
								   JPEGHuffmanTable huffTable);

	/** Sets the AC Huffman coding table at index to the table provided. 
	 * @param huffTable JPEGHuffmanTable that will be assigned
	 * to index tableNum.
	 * @param tableNum - the index of the table to be set.
	 * @exception IllegalArgumentException - thrown if the tableNum
	 * is out of range.  Index must range in value from 0 - 3.
	 */		
	public void	setACHuffmanTable( int tableNum,
								   JPEGHuffmanTable huffTable);


	/**
	 * Sets the mapping between a component and it's DC Huffman Table.
	 * @param component The component to set the mapping for
	 * @param table The DC Huffman table to use for component
	 */
	public void setDCHuffmanComponentMapping( int component, int table);
	/**
	 * Sets the mapping between a component and it's AC Huffman Table.
	 * @param component The component to set the mapping for
	 * @param table The AC Huffman table to use for component
	 */
	public void setACHuffmanComponentMapping( int component, int table);
	/**
	 * Sets the mapping between a component and it's Quantization Table.
	 * @param component The component to set the mapping for
	 * @param table The Quantization Table to use for component
	 */
	public void setQTableComponentMapping( int component, int table);

	/**
	 * Set the flag indicating the validity of the table information
	 * in the ParamBlock.  This is used to indicate if tables should
	 * be included when encoding.
	 */
	public void setImageInfoValid(boolean flag);

	/** 
	 * Set the flag indicating the validity of the image information
	 * in the ParamBlock.  This is used to indicates if image data
	 * should be written when encoding.
	 */
	public void setTableInfoValid(boolean flag);

	/**
	 * Sets the marker data to be written to the output data stream.
	 * This removes any existing marker data in the JPEParm object.
	 * This can be used to remove the default APP0 marker by calling
	 * it with data set to null.
	 * @param marker The marker to set the data for.
	 * @param data the new set of data to be written.
	 */
	public void setMarkerData(int marker, byte[][] data);

	/**
	 * Appends 'data' to the array of byte[] associated with
	 * marker. This will result in additional instance of the marker
	 * being written (one for each byte[] in the array.).
	 * @param marker The marker to add and instance of.
	 * @param data the data to be written.
	 */
	public void addMarkerData(int marker, byte []data);

	/**
	 * Set the MCUs per restart, or 0 for no restart markers.
	 * @param restartInterval number MCUs per restart marker.
	 */
	public void setRestartInterval( int restartInterval );


	/** 
	 * Set the pixel size units This value is copied into the APP0
	 * marker (if that marker is written). This value isn't used by
	 * the JPEG code.
	 * @param unit One of the DENSITY_UNIT_* values.
	 */
	public void setDensityUnit( int unit);
	/** 
	 * Set the horizontal pixel density This value is written into the
	 * APP0 marker. It isn't used by the JPEG code.
	 * @param density the horizontal pixel density, in units
	 * described by @see JPEGParam.getDensityUnit.
	 */
	public void setXDensity( int density );
	/** 
	 * Set the vertical pixel density.  This value is copied into
	 * the JFIF APP0 marker. It isn't used by the JPEG code.
	 * @param density The verticle pixel density, in units
	 * described by @see JPEGParam.getDensityUnit.
	 */
	public void setYDensity( int density );

	/** 
	 * This creates new Quantization tables that replace the currently
	 * installed Quantization tables.  It also updates the Component
	 * QTable mapping to the default for the current encoded COLOR_ID.

	 * The Created Quantization table varies from very high
	 * compression, very low quality, (0.0) to low compression, very
	 * high quality (1.0) based on the quality parameter.<P>
	 
	 * At a quality level of 1.0 the table will be all 1's which will
	 * lead to no loss of data due to quantization (however chrominace
	 * subsampling, if used, and roundoff error in the DCT will still
	 * degrade the image some what).<P>

	 * This is a linear manipulation of the standard Chrominance
	 * Q-Table.<P>

	 * <pre>Some guidelines: 0.75 high quality
	 *                 0.5  medium quality
	 *                 0.25 low quality
	 * </pre>
	 * @param quality 0.0-1.0 setting of desired quality level.
	 * @param forceBaseline force baseline quantization table
	 */
	public void setQuality(float quality, boolean forceBaseline );
}