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libsrc/avi/src/org/monte/media/io/ByteArrayImageInputStream.java

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+/*
+ * @(#)ByteArrayImageInputStream.java  
+ *
+ * Copyright (c) 2008-2011 Werner Randelshofer, Goldau, 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.
+ */
+package org.monte.media.io;
+
+import java.io.IOException;
+import java.nio.ByteOrder;
+
+/**
+ * A {@code ByteArrayImageInputStream} contains
+ * an internal buffer that contains bytes that
+ * may be read from the stream. An internal
+ * counter keeps track of the next byte to
+ * be supplied by the {@code read} method.
+ * <p>
+ * Closing a {@code ByteArrayImageInputStream} has no effect. The methods in
+ * this class can be called after the stream has been closed without
+ * generating an {@code IOException}.
+ *
+ * @author Werner Randelshofer, Hausmatt 10, CH-6405 Goldau
+ * @version $Id: ByteArrayImageInputStream.java 299 2013-01-03 07:40:18Z werner $
+ */
+public class ByteArrayImageInputStream extends ImageInputStreamImpl2 {
+    /**
+     * An array of bytes that was provided
+     * by the creator of the stream. Elements <code>buf[0]</code>
+     * through <code>buf[count-1]</code> are the
+     * only bytes that can ever be read from the
+     * stream;  element <code>buf[streamPos]</code> is
+     * the next byte to be read.
+     */
+    protected byte buf[];
+
+    /**
+     * The index one greater than the last valid character in the input
+     * stream buffer.
+     * This value should always be nonnegative
+     * and not larger than the length of <code>buf</code>.
+     * It  is one greater than the position of
+     * the last byte within <code>buf</code> that
+     * can ever be read  from the input stream buffer.
+     */
+    protected int count;
+
+    /** The offset to the start of the array. */
+    private final int arrayOffset;
+
+    public ByteArrayImageInputStream(byte[] buf) {
+        this(buf, ByteOrder.BIG_ENDIAN);
+    }
+
+    public ByteArrayImageInputStream(byte[] buf, ByteOrder byteOrder) {
+        this(buf, 0, buf.length, byteOrder);
+    }
+
+    public ByteArrayImageInputStream(byte[] buf, int offset, int length, ByteOrder byteOrder) {
+	this.buf = buf;
+        this.streamPos = offset;
+	this.count = Math.min(offset + length, buf.length);
+        this.arrayOffset = offset;
+        this.byteOrder = byteOrder;
+    }
+
+    /**
+     * 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.
+     * <p>
+     * This <code>read</code> method
+     * cannot block.
+     *
+     * @return  the next byte of data, or <code>-1</code> if the end of the
+     *          stream has been reached.
+     */
+    @Override
+    public synchronized int read() {
+        flushBits();
+	return (streamPos < count) ? (buf[(int)(streamPos++)] & 0xff) : -1;
+    }
+
+    /**
+     * Reads up to <code>len</code> bytes of data into an array of bytes
+     * from this input stream.
+     * If <code>streamPos</code> equals <code>count</code>,
+     * then <code>-1</code> is returned to indicate
+     * end of file. Otherwise, the  number <code>k</code>
+     * of bytes read is equal to the smaller of
+     * <code>len</code> and <code>count-streamPos</code>.
+     * If <code>k</code> is positive, then bytes
+     * <code>buf[streamPos]</code> through <code>buf[streamPos+k-1]</code>
+     * are copied into <code>b[off]</code>  through
+     * <code>b[off+k-1]</code> in the manner performed
+     * by <code>System.arraycopy</code>. The
+     * value <code>k</code> is added into <code>streamPos</code>
+     * and <code>k</code> is returned.
+     * <p>
+     * This <code>read</code> method cannot block.
+     *
+     * @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>
+     */
+    @Override
+    public synchronized int read(byte b[], int off, int len) {
+        flushBits();
+	if (b == null) {
+	    throw new NullPointerException();
+	} else if (off < 0 || len < 0 || len > b.length - off) {
+	    throw new IndexOutOfBoundsException();
+	}
+	if (streamPos >= count) {
+	    return -1;
+	}
+	if (streamPos + len > count) {
+	    len = (int)(count - streamPos);
+	}
+	if (len <= 0) {
+	    return 0;
+	}
+	System.arraycopy(buf, (int)streamPos, b, off, len);
+	streamPos += len;
+	return len;
+    }
+
+    /**
+     * Skips <code>n</code> bytes of input from this input stream. Fewer
+     * bytes might be skipped if the end of the input stream is reached.
+     * The actual number <code>k</code>
+     * of bytes to be skipped is equal to the smaller
+     * of <code>n</code> and  <code>count-streamPos</code>.
+     * The value <code>k</code> is added into <code>streamPos</code>
+     * and <code>k</code> is returned.
+     *
+     * @param   n   the number of bytes to be skipped.
+     * @return  the actual number of bytes skipped.
+     */
+    public synchronized long skip(long n) {
+	if (streamPos + n > count) {
+	    n = count - streamPos;
+	}
+	if (n < 0) {
+	    return 0;
+	}
+	streamPos += n;
+	return n;
+    }
+
+    /**
+     * Returns the number of remaining bytes that can be read (or skipped over)
+     * from this input stream.
+     * <p>
+     * The value returned is <code>count&nbsp;- streamPos</code>,
+     * which is the number of bytes remaining to be read from the input buffer.
+     *
+     * @return  the number of remaining bytes that can be read (or skipped
+     *          over) from this input stream without blocking.
+     */
+    public synchronized int available() {
+	return (int)(count - streamPos);
+    }
+
+
+
+    /**
+     * Closing a <tt>ByteArrayInputStream</tt> has no effect. The methods in
+     * this class can be called after the stream has been closed without
+     * generating an <tt>IOException</tt>.
+     * <p>
+     */
+    @Override
+    public void close() {
+        // does nothing!!
+    }
+
+    @Override
+    public long getStreamPosition() throws IOException {
+        checkClosed();
+        return streamPos-arrayOffset;
+    }
+    @Override
+    public void seek(long pos) throws IOException {
+        checkClosed();
+        flushBits();
+
+        // This test also covers pos < 0
+        if (pos < flushedPos) {
+            throw new IndexOutOfBoundsException("pos < flushedPos!");
+        }
+
+        this.streamPos = pos+arrayOffset;
+    }
+
+    private void flushBits() {
+        bitOffset=0;
+    }
+    @Override
+    public long length() {
+        return count-arrayOffset;
+    }
+}