001/*
002 * $RCSfile: StreamSegmentMapper.java,v $
003 *
004 * 
005 * Copyright (c) 2005 Sun Microsystems, Inc. All  Rights Reserved.
006 * 
007 * Redistribution and use in source and binary forms, with or without
008 * modification, are permitted provided that the following conditions
009 * are met: 
010 * 
011 * - Redistribution of source code must retain the above copyright 
012 *   notice, this  list of conditions and the following disclaimer.
013 * 
014 * - Redistribution in binary form must reproduce the above copyright
015 *   notice, this list of conditions and the following disclaimer in 
016 *   the documentation and/or other materials provided with the
017 *   distribution.
018 * 
019 * Neither the name of Sun Microsystems, Inc. or the names of 
020 * contributors may be used to endorse or promote products derived 
021 * from this software without specific prior written permission.
022 * 
023 * This software is provided "AS IS," without a warranty of any 
024 * kind. ALL EXPRESS OR IMPLIED CONDITIONS, REPRESENTATIONS AND 
025 * WARRANTIES, INCLUDING ANY IMPLIED WARRANTY OF MERCHANTABILITY, 
026 * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT, ARE HEREBY
027 * EXCLUDED. SUN MIDROSYSTEMS, INC. ("SUN") AND ITS LICENSORS SHALL 
028 * NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A RESULT OF 
029 * USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS
030 * DERIVATIVES. IN NO EVENT WILL SUN OR ITS LICENSORS BE LIABLE FOR 
031 * ANY LOST REVENUE, PROFIT OR DATA, OR FOR DIRECT, INDIRECT, SPECIAL,
032 * CONSEQUENTIAL, INCIDENTAL OR PUNITIVE DAMAGES, HOWEVER CAUSED AND
033 * REGARDLESS OF THE THEORY OF LIABILITY, ARISING OUT OF THE USE OF OR
034 * INABILITY TO USE THIS SOFTWARE, EVEN IF SUN HAS BEEN ADVISED OF THE
035 * POSSIBILITY OF SUCH DAMAGES. 
036 * 
037 * You acknowledge that this software is not designed or intended for 
038 * use in the design, construction, operation or maintenance of any 
039 * nuclear facility. 
040 *
041 * $Revision: 1.1 $
042 * $Date: 2005/02/11 05:01:21 $
043 * $State: Exp $
044 */
045package com.github.jaiimageio.stream;
046
047/**
048 * An interface for use with the <code>SegmentedImageInputStream</code>
049 * class.  An instance of the <code>StreamSegmentMapper</code>
050 * interface provides the location and length of a segment of a source
051 * <code>ImageInputStream</code> corresponding to the initial portion of
052 * a desired segment of the output stream.
053 *
054 * <p> As an example, consider a mapping between a source
055 * <code>ImageInputStream src</code> and a <code>SegmentedImageInputStream
056 * dst</code> comprising bytes 100-149 and 200-249 of the source
057 * stream.  The <code>dst</code> stream has a reference to an instance
058 * <code>mapper</code> of <code>StreamSegmentMapper</code>.
059 *
060 * <p> A call to <code>dst.seek(0); dst.read(buf, 0, 10)</code> will
061 * result in a call to <code>mapper.getStreamSegment(0, 10)</code>,
062 * returning a new <code>StreamSegment</code> with a starting
063 * position of 100 and a length of 10 (or less).  This indicates that
064 * in order to read bytes 0-9 of the segmented stream, bytes 100-109
065 * of the source stream should be read.
066 *
067 * <p> A call to <code>dst.seek(10); int nbytes = dst.read(buf, 0,
068 * 100)</code> is somewhat more complex, since it will require data
069 * from both segments of <code>src</code>.  The method <code>
070 * mapper.getStreamSegment(10, 100)</code> will be called.  This
071 * method will return a new <code>StreamSegment</code> with a starting
072 * position of 110 and a length of 40 (or less).  The length is
073 * limited to 40 since a longer value would result in a read past the
074 * end of the first segment.  The read will stop after the first 40
075 * bytes and an addition read or reads will be required to obtain the
076 * data contained in the second segment.
077 */
078public interface StreamSegmentMapper {
079
080    /**
081     * Returns a <code>StreamSegment</code> object indicating the
082     * location of the initial portion of a desired segment in the
083     * source stream.  The length of the returned
084     * <code>StreamSegment</code> may be smaller than the desired
085     * length.
086     *
087     * @param pos The desired starting position in the
088     * <code>SegmentedImageInputStream</code>, as a <code>long</code>.
089     * @param length The desired segment length.
090     * @return a StreamSegment object
091     */
092    StreamSegment getStreamSegment(long pos, int length);
093
094    /**
095     * Sets the values of a <code>StreamSegment</code> object
096     * indicating the location of the initial portion of a desired
097     * segment in the source stream.  The length of the returned
098     * <code>StreamSegment</code> may be smaller than the desired
099     * length.
100     *
101     * @param pos The desired starting position in the
102     * <code>SegmentedImageInputStream</code>, as a <code>long</code>.
103     * @param length The desired segment length.
104     * @param seg A <code>StreamSegment</code> object to be overwritten.
105     */
106    void getStreamSegment(long pos, int length, StreamSegment seg);
107}