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/* ShortLookupTable.java -- Java class for a pixel translation table.

   Copyright (C) 2004, 2005, 2006,  Free Software Foundation, Inc.

This file is part of GNU Classpath.

GNU Classpath is free software; you can redistribute it and/or modify

it under the terms of the GNU General Public License as published by

the Free Software Foundation; either version 2, or (at your option)

any later version.

GNU Classpath 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 for more details.

You should have received a copy of the GNU General Public License

along with GNU Classpath; see the file COPYING.  If not, write to the

Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA

02110-1301 USA.

Linking this library statically or dynamically with other modules is

making a combined work based on this library.  Thus, the terms and

conditions of the GNU General Public License cover the whole

combination.

As a special exception, the copyright holders of this library give you

permission to link this library with independent modules to produce an

executable, regardless of the license terms of these independent

modules, and to copy and distribute the resulting executable under

terms of your choice, provided that you also meet, for each linked

independent module, the terms and conditions of the license of that

module.  An independent module is a module which is not derived from

or based on this library.  If you modify this library, you may extend

this exception to your version of the library, but you are not

obligated to do so.  If you do not wish to do so, delete this

exception statement from your version. */

package java.awt.image;

/**

 * ShortLookupTable represents translation arrays for pixel values.  It wraps

 * one or more data arrays for each layer (or component) in an image, such as

 * Alpha, R, G, and B.  When doing translation, the offset is subtracted from

 * the pixel values to allow a subset of an array to be used.

 *

 * @author Jerry Quinn (jlquinn@optonline.net)

 * @version 1.0

 */

public class ShortLookupTable extends LookupTable

{

  // Array of translation tables.

  private short data[][];

  /**

   * Creates a new <code>ShortLookupTable</code> instance.

   *

   * Offset is subtracted from pixel values when looking up in the translation

   * tables.  If data.length is one, the same table is applied to all pixel

   * components.

   *

   * @param offset Offset to be subtracted.

   * @param data Array of lookup tables.

   * @exception IllegalArgumentException if offset < 0 or data.length < 1.

   */

  public ShortLookupTable(int offset, short[][] data)

    throws IllegalArgumentException

  {

    super(offset, data.length);

    // tests show that Sun's implementation creates a new array to store the

    // references from the incoming 'data' array - not sure why, but we'll

    // match that behaviour just in case it matters...

    this.data = new short[data.length][];

    for (int i = 0; i < data.length; i++)

      this.data[i] = data[i];

  }

  /**

   * Creates a new <code>ShortLookupTable</code> instance.

   *

   * Offset is subtracted from pixel values when looking up in the translation

   * table.  The same table is applied to all pixel components.

   *

   * @param offset Offset to be subtracted.

   * @param data Lookup table for all components (<code>null</code> not

   *     permitted).

   * @exception IllegalArgumentException if offset < 0.

   */

  public ShortLookupTable(int offset, short[] data)

    throws IllegalArgumentException

  {

    super(offset, 1);

    if (data == null)

      throw new NullPointerException("Null 'data' argument.");

    this.data = new short[][] {data};

  }

  /**

   * Return the lookup tables.  This is a reference to the actual table, so

   * modifying the contents of the returned array will modify the lookup table.

   *

   * @return The lookup table.

   */

  public final short[][] getTable()

  {

    return data;

  }

  /**

   * Return translated values for a pixel.

   *

   * For each value in the pixel src, use the value minus offset as an index

   * in the component array and copy the value there to the output for the

   * component.  If dest is null, the output is a new array, otherwise the

   * translated values are written to dest.  Dest can be the same array as

   * src.

   *

   * For example, if the pixel src is [2, 4, 3], and offset is 1, the output

   * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the

   * translation arrays.

   *

   * @param src Component values of a pixel.

   * @param dst Destination array for values, or null.

   * @return Translated values for the pixel.

   */

  public int[] lookupPixel(int[] src, int[] dst)

    throws ArrayIndexOutOfBoundsException

  {

    if (dst == null)

      dst = new int[src.length];

    if (data.length == 1)

      for (int i = 0; i < src.length; i++)

        dst[i] = data[0][src[i] - offset];

    else

      for (int i = 0; i < src.length; i++)

        dst[i] = data[i][src[i] - offset];

    return dst;

  }

  /**

   * Return translated values for a pixel.

   *

   * For each value in the pixel src, use the value minus offset as an index

   * in the component array and copy the value there to the output for the

   * component.  If dest is null, the output is a new array, otherwise the

   * translated values are written to dest.  Dest can be the same array as

   * src.

   *

   * For example, if the pixel src is [2, 4, 3], and offset is 1, the output

   * is [comp1[1], comp2[3], comp3[2]], where comp1, comp2, and comp3 are the

   * translation arrays.

   *

   * @param src Component values of a pixel.

   * @param dst Destination array for values, or null.

   * @return Translated values for the pixel.

   *

   */

  public short[] lookupPixel(short[] src, short[] dst)

    throws ArrayIndexOutOfBoundsException

  {

    if (dst == null)

      dst = new short[src.length];

    if (data.length == 1)

      for (int i = 0; i < src.length; i++)

        dst[i] = data[0][((int) src[i]) - offset];

    else

      for (int i = 0; i < src.length; i++)

        dst[i] = data[i][((int) src[i]) - offset];

    return dst;

  }

}