/*
 * $RCSfile: BlkImgDataSrc.java,v $
 * $Revision: 1.1 $
 * $Date: 2005-02-11 05:02:11 $
 * $State: Exp $
 *
 * Class:                   BlkImgDataSrc
 *
 * Description:             Defines methods to transfer image data in blocks.
 *
 *
 *
 * COPYRIGHT:
 *
 * This software module was originally developed by Raphaël Grosbois and
 * Diego Santa Cruz (Swiss Federal Institute of Technology-EPFL); Joel
 * Askelöf (Ericsson Radio Systems AB); and Bertrand Berthelot, David
 * Bouchard, Félix Henry, Gerard Mozelle and Patrice Onno (Canon Research
 * Centre France S.A) in the course of development of the JPEG2000
 * standard as specified by ISO/IEC 15444 (JPEG 2000 Standard). This
 * software module is an implementation of a part of the JPEG 2000
 * Standard. Swiss Federal Institute of Technology-EPFL, Ericsson Radio
 * Systems AB and Canon Research Centre France S.A (collectively JJ2000
 * Partners) agree not to assert against ISO/IEC and users of the JPEG
 * 2000 Standard (Users) any of their rights under the copyright, not
 * including other intellectual property rights, for this software module
 * with respect to the usage by ISO/IEC and Users of this software module
 * or modifications thereof for use in hardware or software products
 * claiming conformance to the JPEG 2000 Standard. Those intending to use
 * this software module in hardware or software products are advised that
 * their use may infringe existing patents. The original developers of
 * this software module, JJ2000 Partners and ISO/IEC assume no liability
 * for use of this software module or modifications thereof. No license
 * or right to this software module is granted for non JPEG 2000 Standard
 * conforming products. JJ2000 Partners have full right to use this
 * software module for his/her own purpose, assign or donate this
 * software module to any third party and to inhibit third parties from
 * using this software module for non JPEG 2000 Standard conforming
 * products. This copyright notice must be included in all copies or
 * derivative works of this software module.
 *
 * Copyright (c) 1999/2000 JJ2000 Partners.
 * */
package jj2000.j2k.image;

/**
 * This interface defines the methods to transfer image data in blocks,
 * without following any particular order (random access). This interface does
 * not define the methods to access the image characteristics, such as width,
 * height, number of components, tiles, etc., or to change the current
 * tile. That is provided by other interfaces such as ImgData.
 *
 * <P>This interface has the notion of a current tile. All data, coordinates
 * and dimensions are always relative to the current tile. If there is only
 * one tile then it is equivalent as having no tiles.
 *
 * <P>A block of requested data may never cross tile boundaries. This should
 * be enforced by the implementing class, or the source of image data.
 *
 * <P>This interface defines the methods that can be used to retrieve image
 * data. Implementing classes need not buffer all the image data, they can ask
 * their source to load the data they need.
 *
 * @see ImgData
 * */
public interface BlkImgDataSrc extends ImgData {

    /**
     * Returns the position of the fixed point in the specified component, or
     * equivalently the number of fractional bits. This is the position of the
     * least significant integral (i.e. non-fractional) bit, which is
     * equivalent to the number of fractional bits. For instance, for
     * fixed-point values with 2 fractional bits, 2 is returned. For
     * floating-point data this value does not apply and 0 should be
     * returned. Position 0 is the position of the least significant bit in
     * the data.
     *
     * @param c The index of the component.
     *
     * @return The position of the fixed-point, which is the same as the
     * number of fractional bits. For floating-point data 0 is returned.
     * */
     public int getFixedPoint(int c);

    /**
     * Returns, in the blk argument, a block of image data containing the
     * specifed rectangular area, in the specified component. The data is
     * returned, as a reference to the internal data, if any, instead of as a
     * copy, therefore the returned data should not be modified.
     *
     * <P>The rectangular area to return is specified by the 'ulx', 'uly', 'w'
     * and 'h' members of the 'blk' argument, relative to the current
     * tile. These members are not modified by this method. The 'offset' and
     * 'scanw' of the returned data can be arbitrary. See the 'DataBlk' class.
     *
     * <P>This method, in general, is more efficient than the 'getCompData()'
     * method since it may not copy the data. However if the array of returned
     * data is to be modified by the caller then the other method is probably
     * preferable.
     *
     * <P>If possible, the data in the returned 'DataBlk' should be the
     * internal data itself, instead of a copy, in order to increase the data
     * transfer efficiency. However, this depends on the particular
     * implementation (it may be more convenient to just return a copy of the
     * data). This is the reason why the returned data should not be modified.
     *
     * <P>If the data array in <tt>blk</tt> is <tt>null</tt>, then a new one
     * is created if necessary. The implementation of this interface may
     * choose to return the same array or a new one, depending on what is more
     * efficient. Therefore, the data array in <tt>blk</tt> prior to the
     * method call should not be considered to contain the returned data, a
     * new array may have been created. Instead, get the array from
     * <tt>blk</tt> after the method has returned.
     *
     * <P>The returned data may have its 'progressive' attribute set. In this
     * case the returned data is only an approximation of the "final" data.
     *
     * @param blk Its coordinates and dimensions specify the area to return,
     * relative to the current tile. Some fields in this object are modified
     * to return the data.
     *
     * @param c The index of the component from which to get the data.
     *
     * @return The requested DataBlk
     *
     * @see #getCompData
     * */
    public DataBlk getInternCompData(DataBlk blk, int c);

    /**
     * Returns, in the blk argument, a block of image data containing the
     * specifed rectangular area, in the specified component. The data is
     * returned, as a copy of the internal data, therefore the returned data
     * can be modified "in place".
     *
     * <P>The rectangular area to return is specified by the 'ulx', 'uly', 'w'
     * and 'h' members of the 'blk' argument, relative to the current
     * tile. These members are not modified by this method. The 'offset' of
     * the returned data is 0, and the 'scanw' is the same as the block's
     * width. See the 'DataBlk' class.
     *
     * <P>This method, in general, is less efficient than the
     * 'getInternCompData()' method since, in general, it copies the
     * data. However if the array of returned data is to be modified by the
     * caller then this method is preferable.
     *
     * <P>If the data array in 'blk' is 'null', then a new one is created. If
     * the data array is not 'null' then it is reused, and it must be large
     * enough to contain the block's data. Otherwise an 'ArrayStoreException'
     * or an 'IndexOutOfBoundsException' is thrown by the Java system.
     *
     * <P>The returned data may have its 'progressive' attribute set. In this
     * case the returned data is only an approximation of the "final" data.
     *
     * @param blk Its coordinates and dimensions specify the area to return,
     * relative to the current tile. If it contains a non-null data array,
     * then it must be large enough. If it contains a null data array a new
     * one is created. Some fields in this object are modified to return the
     * data.
     *
     * @param c The index of the component from which to get the data.
     *
     * @see #getInternCompData
     * */
    public DataBlk getCompData(DataBlk blk, int c);
}
