/*
 * @(#)ImageProducer.java	1.16 00/02/02
 *
 * Copyright 1995-2000 Sun Microsystems, Inc. All Rights Reserved.
 * 
 * This software is the proprietary information of Sun Microsystems, Inc.  
 * Use is subject to license terms.
 * 
 */

package java.awt.image;

/**
 * The interface for objects which can produce the image data for Images.
 * Each image contains an ImageProducer which is used to reconstruct
 * the image whenever it is needed, for example, when a new size of the
 * Image is scaled, or when the width or height of the Image is being
 * requested.
 *
 * @see ImageConsumer
 *
 * @version	1.16 02/02/00
 * @author 	Jim Graham
 */
public interface ImageProducer {
    /**
     * This method is used to register an ImageConsumer with the
     * ImageProducer for access to the image data during a later
     * reconstruction of the Image.  The ImageProducer may, at its
     * discretion, start delivering the image data to the consumer
     * using the ImageConsumer interface immediately, or when the
     * next available image reconstruction is triggered by a call
     * to the startProduction method.
     * @see #startProduction
     */
    public void addConsumer(ImageConsumer ic);

    /**
     * This method determines if a given ImageConsumer object
     * is currently registered with this ImageProducer as one
     * of its consumers.
     */
    public boolean isConsumer(ImageConsumer ic);

    /**
     * This method removes the given ImageConsumer object
     * from the list of consumers currently registered to
     * receive image data.  It is not considered an error
     * to remove a consumer that is not currently registered.
     * The ImageProducer should stop sending data to this
     * consumer as soon as is feasible.
     */
    public void removeConsumer(ImageConsumer ic);

    /**
     * This method both registers the given ImageConsumer object
     * as a consumer and starts an immediate reconstruction of
     * the image data which will then be delivered to this
     * consumer and any other consumer which may have already
     * been registered with the producer.  This method differs
     * from the addConsumer method in that a reproduction of
     * the image data should be triggered as soon as possible.
     * @see #addConsumer
     */
    public void startProduction(ImageConsumer ic);

    /**
     * This method is used by an ImageConsumer to request that
     * the ImageProducer attempt to resend the image data one
     * more time in TOPDOWNLEFTRIGHT order so that higher
     * quality conversion algorithms which depend on receiving
     * pixels in order can be used to produce a better output
     * version of the image.  The ImageProducer is free to
     * ignore this call if it cannot resend the data in that
     * order.  If the data can be resent, then the ImageProducer
     * should respond by executing the following minimum set of
     * ImageConsumer method calls:
     * <pre>
     *	ic.setHints(TOPDOWNLEFTRIGHT | < otherhints >);
     *	ic.setPixels(...);	// As many times as needed
     *	ic.imageComplete();
     * </pre>
     * @see ImageConsumer#setHints
     */
    public void requestTopDownLeftRightResend(ImageConsumer ic);
}