inputstreamimagesource.java

This is a resource based on j2me embedded,if you dont understand,you can connection with me .

/*
 * @(#)InputStreamImageSource.java	1.58 06/10/10
 *
 * Copyright  1990-2008 Sun Microsystems, Inc. All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER
 * 
 * This program 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. 
 * 
 * This program 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 at /legal/license.txt). 
 * 
 * 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 Sun Microsystems, Inc., 4150 Network Circle, Santa
 * Clara, CA 95054 or visit www.sun.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);

        // For basis only, comment the following if-block out as it
        // will bring in the sun.awt.image.ImageRepresentation which
        // is not used in the basis profile.
        /*
        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) {
	    ImageFetcher.add(this);
	    awaitingFetch = true;
	}
    }

    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 {
            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();
            int c7 = is.read();
            int c8 = is.read();
            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);
            } else if (c1 == 137 && c2 == 80 && c3 == 78 &&
                c4 == 71 && c5 == 13 && c6 == 10 &&
                c7 == 26 && c8 == 10) {
                return new PNGImageDecoder(this, is);
            }
        } 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);
    }

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