/* ImageObserver.java -- Java interface for asynchronous updates to an image
   Copyright (C) 1999 Free Software Foundation, Inc.

This file is part of the non-peer AWT libraries of GNU Classpath.

This library is free software; you can redistribute it and/or modify
it under the terms of the GNU Library General Public License as published 
by the Free Software Foundation, either version 2 of the License, or
(at your option) any later verion.

This library 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 Library General Public License for more details.

You should have received a copy of the GNU Library General Public License
along with this library; if not, write to the Free Software Foundation
Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307 USA. */


package java.awt.image;

import java.awt.Image;

/**
 * An object implementing the <code>ImageObserver</code> interface can
 * receive updates on image construction from an
 * <code>ImageProducer</code> asynchronously.
 *
 * @see ImageProducer
 * @author C. Brian Jones (cbj@gnu.org) 
 */
public interface ImageObserver
{
    /**
     * The width of the image has been provided as the
     * <code>width</code> argument to <code>imageUpdate</code>.
     *
     * @see #imageUpdate 
     */
    public static final int WIDTH = 1;

    /**
     * The height of the image has been provided as the
     * <code>height</code> argument to <code>imageUpdate</code>.
     *
     * @see #imageUpdate 
     */
    public static final int HEIGHT = 2;

    /**
     * The properties of the image have been provided.
     *
     * @see #imageUpdate
     * @see java.awt.Image#getProperty (java.lang.String, java.awt.image.ImageObserver)
     */
    public static final int PROPERTIES = 4;

    /**
     * More pixels are now available for drawing a scaled variation of
     * the image.
     *
     * @see #imageUpdate 
     */
    public static final int SOMEBITS = 8;

    /**
     * All the pixels needed to draw a complete frame of a multi-frame
     * image are available.
     *
     * @see #imageUpdate 
     */
    public static final int FRAMEBITS = 16;

    /**
     * An image with a single frame, a static image, is complete.
     *
     * @see #imageUpdate
     */
    public static final int ALLBITS = 32;

    /**
     * An error was encountered while producing the image.
     *
     * @see #imageUpdate
     */
    public static final int ERROR = 64;

    /**
     * Production of the image was aborted.
     *
     * @see #imageUpdate
     */
    public static final int ABORT = 128;

    /**
     * This is a callback method for an asynchronous image producer to
     * provide updates on the production of the image as it happens.
     *
     * @param image the image the update refers to
     * @param flags a bit mask indicating what is provided with this update
     * @param x the x coordinate of the image
     * @param y the y coordinate of the image
     * @param width the width of the image
     * @param height the height of the image
     * 
     * @see java.awt.Image 
     */
    public abstract boolean imageUpdate(Image image, int flags, int x, 
					int y, int width, int height);
}