/*
* Copyright (c) 2000, 2006, Oracle and/or its affiliates. All rights reserved.
* DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
*
* This code is free software; you can redistribute it and/or modify it
* under the terms of the GNU General Public License version 2 only, as
* published by the Free Software Foundation. Oracle designates this
* particular file as subject to the "Classpath" exception as provided
* by Oracle in the LICENSE file that accompanied this code.
*
* This code is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
* version 2 for more details (a copy is included in the LICENSE file that
* accompanied this code).
*
* You should have received a copy of the GNU General Public License version
* 2 along with this work; if not, write to the Free Software Foundation,
* Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
*
* Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
* or visit www.oracle.com if you need additional information or have any
* questions.
*/
package javax.imageio.stream;
import java.io.IOException;
import java.io.OutputStream;
/**
* An implementation of <code>ImageOutputStream</code> that writes its
* output to a regular <code>OutputStream</code>. A memory buffer is
* used to cache at least the data between the discard position and
* the current write position. The only constructor takes an
* <code>OutputStream</code>, so this class may not be used for
* read/modify/write operations. Reading can occur only on parts of
* the stream that have already been written to the cache and not
* yet flushed.
*
*/
public class MemoryCacheImageOutputStream extends ImageOutputStreamImpl {
private OutputStream stream;
private MemoryCache cache = new MemoryCache();
/**
* Constructs a <code>MemoryCacheImageOutputStream</code> that will write
* to a given <code>OutputStream</code>.
*
* @param stream an <code>OutputStream</code> to write to.
*
* @exception IllegalArgumentException if <code>stream</code> is
* <code>null</code>.
*/
public MemoryCacheImageOutputStream(OutputStream stream) {
if (stream == null) {
throw new IllegalArgumentException("stream == null!");
}
this.stream = stream;
}
public int read() throws IOException {
checkClosed();
bitOffset = 0;
int val = cache.read(streamPos);
if (val != -1) {
++streamPos;
}
return val;
}
public int read(byte[] b, int off, int len) throws IOException {
checkClosed();
if (b == null) {
throw new NullPointerException("b == null!");
}
// Fix 4467608: read([B,I,I) works incorrectly if len<=0
if (off < 0 || len < 0 || off + len > b.length || off + len < 0) {
throw new IndexOutOfBoundsException
("off < 0 || len < 0 || off+len > b.length || off+len < 0!");
}
bitOffset = 0;
if (len == 0) {
return 0;
}
// check if we're already at/past EOF i.e.
// no more bytes left to read from cache
long bytesLeftInCache = cache.getLength() - streamPos;
if (bytesLeftInCache <= 0) {
return -1; // EOF
}
// guaranteed by now that bytesLeftInCache > 0 && len > 0
// and so the rest of the error checking is done by cache.read()
// NOTE that alot of error checking is duplicated
len = (int)Math.min(bytesLeftInCache, (long)len);
cache.read(b, off, len, streamPos);
streamPos += len;
return len;
}
public void write(int b) throws IOException {
flushBits(); // this will call checkClosed() for us
cache.write(b, streamPos);
++streamPos;
}
public void write(byte[] b, int off, int len) throws IOException {
flushBits(); // this will call checkClosed() for us
cache.write(b, off, len, streamPos);
streamPos += len;
}
public long length() {
try {
checkClosed();
return cache.getLength();
} catch (IOException e) {
return -1L;
}
}
/**
* Returns <code>true</code> since this
* <code>ImageOutputStream</code> caches data in order to allow
* seeking backwards.
*
* @return <code>true</code>.
*
* @see #isCachedMemory
* @see #isCachedFile
*/
public boolean isCached() {
return true;
}
/**
* Returns <code>false</code> since this
* <code>ImageOutputStream</code> does not maintain a file cache.
*
* @return <code>false</code>.
*
* @see #isCached
* @see #isCachedMemory
*/
public boolean isCachedFile() {
return false;
}
/**
* Returns <code>true</code> since this
* <code>ImageOutputStream</code> maintains a main memory cache.
*
* @return <code>true</code>.
*
* @see #isCached
* @see #isCachedFile
*/
public boolean isCachedMemory() {
return true;
}
/**
* Closes this <code>MemoryCacheImageOutputStream</code>. All
* pending data is flushed to the output, and the cache
* is released. The destination <code>OutputStream</code>
* is not closed.
*/
public void close() throws IOException {
long length = cache.getLength();
seek(length);
flushBefore(length);
super.close();
cache.reset();
cache = null;
stream = null;
}
public void flushBefore(long pos) throws IOException {
long oFlushedPos = flushedPos;
super.flushBefore(pos); // this will call checkClosed() for us
long flushBytes = flushedPos - oFlushedPos;
cache.writeToStream(stream, oFlushedPos, flushBytes);
cache.disposeBefore(flushedPos);
stream.flush();
}
}