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/* EncodeRLE4.java --

   Copyright (C) 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 gnu.javax.imageio.bmp;

import java.awt.image.BufferedImage;

import java.awt.image.PixelGrabber;

import java.io.IOException;

import java.nio.BufferUnderflowException;

import java.nio.ByteBuffer;

import javax.imageio.IIOImage;

import javax.imageio.ImageWriteParam;

import javax.imageio.metadata.IIOMetadata;

import javax.imageio.stream.ImageOutputStream;

public class EncodeRLE4

    extends BMPEncoder

{

  protected BMPInfoHeader infoHeader;

  protected BMPFileHeader fileHeader;

  protected long offset;

  /**

   * RLE control codes

   */

  private static final byte ESCAPE = (byte)0;

  private static final byte EOL = (byte)0; // end of line

  private static final byte EOB = (byte)1; // end of bitmap

  private static final byte DELTA = (byte)2; // delta

  /**

   * Constructs an instance of this class.

   *

   * @param fh - the file header to use.

   * @param ih - the info header to use.

   */

  public EncodeRLE4(BMPFileHeader fh, BMPInfoHeader ih)

  {

    super();

    fileHeader = fh;

    infoHeader = ih;

    offset = BMPFileHeader.SIZE + BMPInfoHeader.SIZE;

  }

  /**

   * The image encoder.

   *

   * @param o - the image output stream

   * @param streamMetadata - metadata associated with this stream, or

   * null

   * @param image - an IIOImage containing image data.

   * @param param - image writing parameters, or null

   * @exception IOException if a write error occurs

   */

  public void encode(ImageOutputStream o, IIOMetadata streamMetadata,

                     IIOImage image, ImageWriteParam param) throws IOException

  {

    int size;

    int value;

    int j;

    int rowCount;

    int rowIndex;

    int lastRowIndex;

    int[] bitmap;

    size = (infoHeader.biWidth * infoHeader.biHeight) - 1;

    rowCount = 1;

    rowIndex = size - infoHeader.biWidth;

    lastRowIndex = rowIndex;

    ByteBuffer buf = ByteBuffer.allocate(size);

    try

      {

        bitmap = new int[infoHeader.biWidth * infoHeader.biHeight];

        PixelGrabber pg = new PixelGrabber((BufferedImage) image.getRenderedImage(),

                                           0, 0, infoHeader.biWidth,

                                           infoHeader.biHeight, bitmap, 0,

                                           infoHeader.biWidth);

        pg.grabPixels();

        for (j = 0; j < size; j++)

          {

            value = bitmap[rowIndex];

            buf.put((byte) (value & 0xFF));

            if (rowCount == infoHeader.biWidth)

              {

                rowCount = 1;

                rowIndex = lastRowIndex - infoHeader.biWidth;

                lastRowIndex = rowIndex;

              }

            else

              rowCount++;

            rowIndex++;

          }

        buf.flip();

        o.write(uncompress(infoHeader.biWidth, infoHeader.biHeight, buf));

      }

    catch (Exception wb)

      {

        wb.printStackTrace();

      }

  }

  /**

   * Uncompresses the image stored in the buffer.

   *

   * @param w - the width of the image

   * @param h - the height of the image

   * @param buf - the ByteBuffer containing the pixel values.

   * @return byte array containing the uncompressed image

   * @throws IOException if an error is encountered while reading

   * buffer.

   */

  private byte[] uncompress(int w, int h, ByteBuffer buf)

      throws IOException

  {

    byte[] cmd = new byte[2];

    byte[] data = new byte[w * h >> 1];

    int offIn = 0;

    int x = 0, y = 0;

    w += (w & 1);

    w = w >> 1;

    try

      {

        while (((x >> 1) + y * w) < w * h)

          {

            try

            {

              buf.get(cmd);

            }

            catch (BufferUnderflowException e)

            {

              throw new IOException("Error reading compressed data.");

            }

            if (cmd[0] == ESCAPE)

              {

                switch (cmd[1])

                  {

                  case EOB:

                    return data;

                  case EOL:

                    x = 0;

                    y++;

                    break;

                  case DELTA:

                    try

                    {

                      buf.get(cmd);

                    }

                    catch (BufferUnderflowException e)

                    {

                      throw new IOException("Error reading compressed data.");

                    }

                    int dx = cmd[0] & (0xFF);

                    int dy = cmd[1] & (0xFF);

                    x += dx;

                    y += dy;

                    break;

                  default:

                    int length = cmd[1] & (0xFF);

                    int bytesize = length;

                    bytesize += (bytesize & 1);

                    bytesize >>= 1;

                    bytesize += (bytesize & 1);

                    byte[] run = new byte[bytesize];

                    try

                    {

                      buf.get(run);

                    }

                    catch (BufferUnderflowException e)

                    {

                      throw new IOException("Error reading compressed data.");

                    }

                    if ((x & 1) == 0)

                      {

                        length += (length & 1);

                        length >>= 1;

                        System.arraycopy(run, 0, data,

                                         ((x >> 1) + w * (h - y - 1)), length);

                      }

                    else

                      {

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

                          {

                            if ((i & 1) == 0)

                              data[((x + i) >> 1) + w * (h - y - 1)] |= ((run[i >> 1] & 0xF0) >> 4);

                            else

                              data[((x + i) >> 1) + w * (h - y - 1)] |= ((run[i >> 1] & 0x0F) << 4);

                          }

                      }

                    x += cmd[1] & (0xFF);

                    break;

                  }

              }

            else

              {

                int length = cmd[0] & (0xFF);

                if ((x & 1) == 0)

                  {

                    length += (length & 1);

                    length >>= 1;

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

                      data[(h - y - 1) * w + i + (x >> 1)] = cmd[1];

                  }

                else

                  {

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

                      {

                        if ((i & 1) == 0)

                          data[((x + i) >> 1) + w * (h - y - 1)] |= ((cmd[1] & 0xF0) >> 4);

                        else

                          data[((x + i) >> 1) + w * (h - y - 1)] |= ((cmd[1] & 0x0F) << 4);

                      }

                  }

                x += cmd[0] & (0xFF);

              }

          }

        return data;

      }

    catch (ArrayIndexOutOfBoundsException e)

      {

        throw new BMPException("Invalid RLE data.");

      }

  }

}