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	/*
	* Copyright (c) 1995, 2011, 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 sun.awt.image;

	import java.awt.image.*;
	import java.io.InputStream;
	import java.io.IOException;
	import java.io.BufferedInputStream;
	import java.util.Hashtable;

	public abstract class InputStreamImageSource implements ImageProducer,
	ImageFetchable
	{
	ImageConsumerQueue consumers;

	ImageDecoder decoder;
	ImageDecoder decoders;

	boolean awaitingFetch = false;

	abstract boolean checkSecurity(Object context, boolean quiet);

	int countConsumers(ImageConsumerQueue cq) {
	int i = 0;
	while (cq != null) {
	i++;
	cq = cq.next;
	}
	return i;
	}

	synchronized int countConsumers() {
	ImageDecoder id = decoders;
	int i = countConsumers(consumers);
	while (id != null) {
	i += countConsumers(id.queue);
	id = id.next;
	}
	return i;
	}

	public void addConsumer(ImageConsumer ic) {
	addConsumer(ic, false);
	}

	synchronized void printQueue(ImageConsumerQueue cq, String prefix) {
	while (cq != null) {
	System.out.println(prefix+cq);
	cq = cq.next;
	}
	}

	synchronized void printQueues(String title) {
	System.out.println(title+"[ -----------");
	printQueue(consumers, " ");
	for (ImageDecoder id = decoders; id != null; id = id.next) {
	System.out.println(" "+id);
	printQueue(id.queue, " ");
	}
	System.out.println("----------- ]"+title);
	}

	synchronized void addConsumer(ImageConsumer ic, boolean produce) {
	checkSecurity(null, false);
	for (ImageDecoder id = decoders; id != null; id = id.next) {
	if (id.isConsumer(ic)) {
	// This consumer is already being fed.
	return;
	}
	}
	ImageConsumerQueue cq = consumers;
	while (cq != null && cq.consumer != ic) {
	cq = cq.next;
	}
	if (cq == null) {
	cq = new ImageConsumerQueue(this, ic);
	cq.next = consumers;
	consumers = cq;
	} else {
	if (!cq.secure) {
	Object context = null;
	SecurityManager security = System.getSecurityManager();
	if (security != null) {
	context = security.getSecurityContext();
	}
	if (cq.securityContext == null) {
	cq.securityContext = context;
	} else if (!cq.securityContext.equals(context)) {
	// If there are two different security contexts that both
	// have a handle on the same ImageConsumer, then there has
	// been a security breach and whether or not they trade
	// image data is small fish compared to what they could be
	// trading. Throw a Security exception anyway...
	errorConsumer(cq, false);
	throw new SecurityException("Applets are trading image data!");
	}
	}
	cq.interested = true;
	}
	if (produce && decoder == null) {
	startProduction();
	}
	}

	public synchronized boolean isConsumer(ImageConsumer ic) {
	for (ImageDecoder id = decoders; id != null; id = id.next) {
	if (id.isConsumer(ic)) {
	return true;
	}
	}
	return ImageConsumerQueue.isConsumer(consumers, ic);
	}

	private void errorAllConsumers(ImageConsumerQueue cq, boolean needReload) {
	while (cq != null) {
	if (cq.interested) {
	errorConsumer(cq, needReload);
	}
	cq = cq.next;
	}
	}

	private void errorConsumer(ImageConsumerQueue cq, boolean needReload) {
	cq.consumer.imageComplete(ImageConsumer.IMAGEERROR);
	if ( needReload && cq.consumer instanceof ImageRepresentation) {
	((ImageRepresentation)cq.consumer).image.flush();
	}
	removeConsumer(cq.consumer);
	}

	public synchronized void removeConsumer(ImageConsumer ic) {
	for (ImageDecoder id = decoders; id != null; id = id.next) {
	id.removeConsumer(ic);
	}
	consumers = ImageConsumerQueue.removeConsumer(consumers, ic, false);
	}

	public void startProduction(ImageConsumer ic) {
	addConsumer(ic, true);
	}

	private synchronized void startProduction() {
	if (!awaitingFetch) {
	if (ImageFetcher.add(this)) {
	awaitingFetch = true;
	} else {
	ImageConsumerQueue cq = consumers;
	consumers = null;
	errorAllConsumers(cq, false);
	}
	}
	}

	private synchronized void stopProduction() {
	if (awaitingFetch) {
	ImageFetcher.remove(this);
	awaitingFetch = false;
	}
	}

	public void requestTopDownLeftRightResend(ImageConsumer ic) {
	}

	protected abstract ImageDecoder getDecoder();

	protected ImageDecoder decoderForType(InputStream is,
	String content_type) {
	// Don't believe the content type - file extensions can
	// lie.
	/*
	if (content_type.equals("image/gif")) {
	return new GifImageDecoder(this, is);
	} else if (content_type.equals("image/jpeg")) {
	return new JPEGImageDecoder(this, is);
	} else if (content_type.equals("image/x-xbitmap")) {
	return new XbmImageDecoder(this, is);
	}
	else if (content_type == URL.content_jpeg) {
	return new JpegImageDecoder(this, is);
	} else if (content_type == URL.content_xbitmap) {
	return new XbmImageDecoder(this, is);
	} else if (content_type == URL.content_xpixmap) {
	return new Xpm2ImageDecoder(this, is);
	}
	*/

	return null;
	}

	protected ImageDecoder getDecoder(InputStream is) {
	if (!is.markSupported())
	is = new BufferedInputStream(is);
	try {
	/* changed to support png
	is.mark(6);
	*/
	is.mark(8);
	int c1 = is.read();
	int c2 = is.read();
	int c3 = is.read();
	int c4 = is.read();
	int c5 = is.read();
	int c6 = is.read();
	// added to support png
	int c7 = is.read();
	int c8 = is.read();
	// end of adding
	is.reset();
	is.mark(-1);

	if (c1 == 'G' && c2 == 'I' && c3 == 'F' && c4 == '8') {
	return new GifImageDecoder(this, is);
	} else if (c1 == '\377' && c2 == '\330' && c3 == '\377') {
	return new JPEGImageDecoder(this, is);
	} else if (c1 == '#' && c2 == 'd' && c3 == 'e' && c4 == 'f') {
	return new XbmImageDecoder(this, is);
	// } else if (c1 == '!' && c2 == ' ' && c3 == 'X' && c4 == 'P' &&
	// c5 == 'M' && c6 == '2') {
	// return new Xpm2ImageDecoder(this, is);
	// added to support png
	} else if (c1 == 137 && c2 == 80 && c3 == 78 &&
	c4 == 71 && c5 == 13 && c6 == 10 &&
	c7 == 26 && c8 == 10) {
	return new PNGImageDecoder(this, is);
	}
	// end of adding
	} catch (IOException e) {
	}

	return null;
	}

	public void doFetch() {
	synchronized (this) {
	if (consumers == null) {
	awaitingFetch = false;
	return;
	}
	}
	ImageDecoder imgd = getDecoder();
	if (imgd == null) {
	badDecoder();
	} else {
	setDecoder(imgd);
	try {
	imgd.produceImage();
	} catch (IOException e) {
	e.printStackTrace();
	// the finally clause will send an error.
	} catch (ImageFormatException e) {
	e.printStackTrace();
	// the finally clause will send an error.
	} finally {
	removeDecoder(imgd);
	if ( Thread.currentThread().isInterrupted() \|\| !Thread.currentThread().isAlive()) {
	errorAllConsumers(imgd.queue, true);
	} else {
	errorAllConsumers(imgd.queue, false);
	}
	}
	}
	}

	private void badDecoder() {
	ImageConsumerQueue cq;
	synchronized (this) {
	cq = consumers;
	consumers = null;
	awaitingFetch = false;
	}
	errorAllConsumers(cq, false);
	}

	private void setDecoder(ImageDecoder mydecoder) {
	ImageConsumerQueue cq;
	synchronized (this) {
	mydecoder.next = decoders;
	decoders = mydecoder;
	decoder = mydecoder;
	cq = consumers;
	mydecoder.queue = cq;
	consumers = null;
	awaitingFetch = false;
	}
	while (cq != null) {
	if (cq.interested) {
	// Now that there is a decoder, security may have changed
	// so reverify it here, just in case.
	if (!checkSecurity(cq.securityContext, true)) {
	errorConsumer(cq, false);
	}
	}
	cq = cq.next;
	}
	}

	private synchronized void removeDecoder(ImageDecoder mydecoder) {
	doneDecoding(mydecoder);
	ImageDecoder idprev = null;
	for (ImageDecoder id = decoders; id != null; id = id.next) {
	if (id == mydecoder) {
	if (idprev == null) {
	decoders = id.next;
	} else {
	idprev.next = id.next;
	}
	break;
	}
	idprev = id;
	}
	}

	synchronized void doneDecoding(ImageDecoder mydecoder) {
	if (decoder == mydecoder) {
	decoder = null;
	if (consumers != null) {
	startProduction();
	}
	}
	}

	void latchConsumers(ImageDecoder id) {
	doneDecoding(id);
	}

	synchronized void flush() {
	decoder = null;
	}
	}

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