/*
 * @(#)IIOParam.java	1.30 05/11/17
 *
 * Copyright 2006 Sun Microsystems, Inc. All rights reserved.
 * SUN PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */

package javax.imageio;

import java.awt.Point;
import java.awt.Rectangle;

/**
 * A superclass of all classes describing how streams should be 
 * decoded or encoded.  This class contains all the variables and
 * methods that are shared by <code>ImageReadParam</code> and
 * <code>ImageWriteParam</code>.
 * 
 * <p> This class provides mechanisms to specify a source region and a
 * destination region.  When reading, the source is the stream and 
 * the in-memory image is the destination.  When writing, these are
 * reversed.  In the case of writing, destination regions may be used
 * only with a writer that supports pixel replacement.
 * <p>
 * Decimation subsampling may be specified for both readers
 * and writers, using a movable subsampling grid.
 * <p>
 * Subsets of the source and destination bands may be selected.
 *
 * @version 0.5
 */
public abstract class IIOParam {

    /**
     * The source region, on <code>null</code> if none is set.
     */
    protected Rectangle sourceRegion = null;

    /**
     * The decimation subsampling to be applied in the horizontal
     * direction.  By default, the value is <code>1</code>.
     * The value must not be negative or 0.
     */
    protected int sourceXSubsampling = 1;

    /**
     * The decimation subsampling to be applied in the vertical
     * direction.  By default, the value is <code>1</code>.
     * The value must not be negative or 0.
     */
    protected int sourceYSubsampling = 1;

    /**
     * A horizontal offset to be applied to the subsampling grid before
     * subsampling.  The first pixel to be used will be offset this
     * amount from the origin of the region, or of the image if no
     * region is specified.
     */
    protected int subsamplingXOffset = 0;

    /**
     * A vertical offset to be applied to the subsampling grid before
     * subsampling.  The first pixel to be used will be offset this
     * amount from the origin of the region, or of the image if no
     * region is specified.
     */
    protected int subsamplingYOffset = 0;
    
    /**
     * An array of <code>int</code>s indicating which source bands
     * will be used, or <code>null</code>.  If <code>null</code>, the
     * set of source bands to be used is as described in the comment
     * for the <code>setSourceBands</code> method.  No value should
     * be allowed to be negative.
     */
    protected int[] sourceBands = null;

    /**
     * An <code>ImageTypeSpecifier</code> to be used to generate a
     * destination image when reading, or to set the output color type
     * when writing.  If non has been setm the value will be
     * <code>null</code>.  By default, the value is <code>null</code>.
     */
    protected ImageTypeSpecifier destinationType = null;

    /**
     * The offset in the destination where the upper-left decoded
     * pixel should be placed.  By default, the value is (0, 0).
     */
    protected Point destinationOffset = new Point(0, 0);

    /**
     * The default <code>IIOParamController</code> that will be
     * used to provide settings for this <code>IIOParam</code>
     * object when the <code>activateController</code> method
     * is called.  This default should be set by subclasses
     * that choose to provide their own default controller, 
     * usually a GUI, for setting parameters.
     *
     * @see IIOParamController