ImageInputStreamAdapter.java

/*
 * @(#)ImageInputStreamAdapter.java  1.0  2009-12-17
 * 
 * Copyright (c) 2009 Werner Randelshofer, Immensee, Switzerland.
 * All rights reserved.
 *
 * You may not use, copy or modify this file, except in compliance with the
 * license agreement you entered into with Werner Randelshofer.
 * For details see accompanying license terms.
 */

import java.io.FilterInputStream;
import java.io.IOException;
import javax.imageio.stream.ImageInputStream;

/**
 * ImageInputStreamAdapter.
 *
 * @author Werner Randelshofer
 * @version 1.0 2009-12-17 Created.
 */
public class ImageInputStreamAdapter extends FilterInputStream {
    private ImageInputStream iis;
    public ImageInputStreamAdapter(ImageInputStream iis) {
        super(null);
        this.iis=iis;
    }

    /**
     * Reads the next byte of data from this input stream. The value
     * byte is returned as an <code>int</code> in the range
     * <code>0</code> to <code>255</code>. If no byte is available
     * because the end of the stream has been reached, the value
     * <code>-1</code> is returned. This method blocks until input data
     * is available, the end of the stream is detected, or an exception
     * is thrown.
     * <p>
     * This method
     * simply performs <code>in.read()</code> and returns the result.
     *
     * @return     the next byte of data, or <code>-1</code> if the end of the
     *             stream is reached.
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    @Override
    public int read() throws IOException {
	return iis.read();
    }

    /**
     * Reads up to <code>len</code> bytes of data from this input stream
     * into an array of bytes. If <code>len</code> is not zero, the method
     * blocks until some input is available; otherwise, no
     * bytes are read and <code>0</code> is returned.
     * <p>
     * This method simply performs <code>in.read(b, off, len)</code>
     * and returns the result.
     *
     * @param      b     the buffer into which the data is read.
     * @param      off   the start offset in the destination array <code>b</code>
     * @param      len   the maximum number of bytes read.
     * @return     the total number of bytes read into the buffer, or
     *             <code>-1</code> if there is no more data because the end of
     *             the stream has been reached.
     * @exception  NullPointerException If <code>b</code> is <code>null</code>.
     * @exception  IndexOutOfBoundsException If <code>off</code> is negative,
     * <code>len</code> is negative, or <code>len</code> is greater than
     * <code>b.length - off</code>
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    @Override
    public int read(byte b[], int off, int len) throws IOException {
	return iis.read(b, off, len);
    }

    /**
     * {@inheritDoc}
     * <p>
     * This method simply performs <code>in.skip(n)</code>.
     */
    @Override
    public long skip(long n) throws IOException {
	return iis.skipBytes(n);
    }

    /**
     * Returns an estimate of the number of bytes that can be read (or
     * skipped over) from this input stream without blocking by the next
     * caller of a method for this input stream. The next caller might be
     * the same thread or another thread.  A single read or skip of this
     * many bytes will not block, but may read or skip fewer bytes.
     * <p>
     * This method returns the result of {@link #in in}.available().
     *
     * @return     an estimate of the number of bytes that can be read (or skipped
     *             over) from this input stream without blocking.
     * @exception  IOException  if an I/O error occurs.
     */
    @Override
    public int available() throws IOException {
	return  (iis.isCached()) ? //
            (int)Math.min(Integer.MAX_VALUE, iis.length() - iis.getStreamPosition()) :
            0;
    }

    /**
     * Closes this input stream and releases any system resources
     * associated with the stream.
     * This
     * method simply performs <code>in.close()</code>.
     *
     * @exception  IOException  if an I/O error occurs.
     * @see        java.io.FilterInputStream#in
     */
    @Override
    public void close() throws IOException {
	iis.close();
    }

    /**
     * Marks the current position in this input stream. A subsequent
     * call to the <code>reset</code> method repositions this stream at
     * the last marked position so that subsequent reads re-read the same bytes.
     * <p>
     * The <code>readlimit</code> argument tells this input stream to
     * allow that many bytes to be read before the mark position gets
     * invalidated.
     * <p>
     * This method simply performs <code>in.mark(readlimit)</code>.
     *
     * @param   readlimit   the maximum limit of bytes that can be read before
     *                      the mark position becomes invalid.
     * @see     java.io.FilterInputStream#in
     * @see     java.io.FilterInputStream#reset()
     */
    @Override
    public synchronized void mark(int readlimit) {
	iis.mark();
    }

    /**
     * Repositions this stream to the position at the time the
     * <code>mark</code> method was last called on this input stream.
     * <p>
     * This method
     * simply performs <code>in.reset()</code>.
     * <p>
     * Stream marks are intended to be used in
     * situations where you need to read ahead a little to see what's in
     * the stream. Often this is most easily done by invoking some
     * general parser. If the stream is of the type handled by the
     * parse, it just chugs along happily. If the stream is not of
     * that type, the parser should toss an exception when it fails.
     * If this happens within readlimit bytes, it allows the outer
     * code to reset the stream and try another parser.
     *
     * @exception  IOException  if the stream has not been marked or if the
     *               mark has been invalidated.
     * @see        java.io.FilterInputStream#in
     * @see        java.io.FilterInputStream#mark(int)
     */
    @Override
    public synchronized void reset() throws IOException {
	iis.reset();
    }

    /**
     * Tests if this input stream supports the <code>mark</code>
     * and <code>reset</code> methods.
     * This method
     * simply performs <code>in.markSupported()</code>.
     *
     * @return  <code>true</code> if this stream type supports the
     *          <code>mark</code> and <code>reset</code> method;
     *          <code>false</code> otherwise.
     * @see     java.io.FilterInputStream#in
     * @see     java.io.InputStream#mark(int)
     * @see     java.io.InputStream#reset()
     */
    @Override
    public boolean markSupported() {
	return true;
    }

}