Source for gnu.javax.imageio.bmp.EncodeRLE8

   1: /* EncodeRGB32.java --
   2:    Copyright (C) 2006 Free Software Foundation, Inc.
   3: 
   4: This file is part of GNU Classpath.
   5: 
   6: GNU Classpath is free software; you can redistribute it and/or modify
   7: it under the terms of the GNU General Public License as published by
   8: the Free Software Foundation; either version 2, or (at your option)
   9: any later version.
  10: 
  11: GNU Classpath is distributed in the hope that it will be useful, but
  12: WITHOUT ANY WARRANTY; without even the implied warranty of
  13: MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  14: General Public License for more details.
  15: 
  16: You should have received a copy of the GNU General Public License
  17: along with GNU Classpath; see the file COPYING.  If not, write to the
  18: Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  19: 02110-1301 USA.
  20: 
  21: Linking this library statically or dynamically with other modules is
  22: making a combined work based on this library.  Thus, the terms and
  23: conditions of the GNU General Public License cover the whole
  24: combination.
  25: 
  26: As a special exception, the copyright holders of this library give you
  27: permission to link this library with independent modules to produce an
  28: executable, regardless of the license terms of these independent
  29: modules, and to copy and distribute the resulting executable under
  30: terms of your choice, provided that you also meet, for each linked
  31: independent module, the terms and conditions of the license of that
  32: module.  An independent module is a module which is not derived from
  33: or based on this library.  If you modify this library, you may extend
  34: this exception to your version of the library, but you are not
  35: obligated to do so.  If you do not wish to do so, delete this
  36: exception statement from your version. */
  37: 
  38: 
  39: package gnu.javax.imageio.bmp;
  40: 
  41: import java.awt.image.BufferedImage;
  42: import java.awt.image.PixelGrabber;
  43: import java.io.IOException;
  44: import java.nio.BufferUnderflowException;
  45: import java.nio.ByteBuffer;
  46: 
  47: import javax.imageio.IIOImage;
  48: import javax.imageio.ImageWriteParam;
  49: import javax.imageio.metadata.IIOMetadata;
  50: import javax.imageio.stream.ImageOutputStream;
  51: 
  52: public class EncodeRLE8
  53:     extends BMPEncoder
  54: {
  55:   protected BMPInfoHeader infoHeader;
  56:   protected BMPFileHeader fileHeader;
  57:   protected long offset;
  58: 
  59:   /**
  60:    * RLE control codes
  61:    */
  62:   private static final byte ESCAPE = (byte)0;
  63:   private static final byte EOL = (byte)0; // end of line
  64:   private static final byte EOB = (byte)1; // end of bitmap
  65:   private static final byte DELTA = (byte)2; // delta
  66: 
  67:   /**
  68:    * Constructs an instance of this class.
  69:    *
  70:    * @param fh - the file header to use.
  71:    * @param ih - the info header to use.
  72:    */
  73:   public EncodeRLE8(BMPFileHeader fh, BMPInfoHeader ih)
  74:   {
  75:     super();
  76:     fileHeader = fh;
  77:     infoHeader = ih;
  78:     offset = BMPFileHeader.SIZE + BMPInfoHeader.SIZE;
  79:   }
  80: 
  81:   /**
  82:    * The image encoder.
  83:    *
  84:    * @param o - the image output stream
  85:    * @param streamMetadata - metadata associated with this stream, or
  86:    * null
  87:    * @param image - an IIOImage containing image data.
  88:    * @param param - image writing parameters, or null
  89:    * @exception IOException if a write error occurs
  90:    */
  91:   public void encode(ImageOutputStream o, IIOMetadata streamMetadata,
  92:                      IIOImage image, ImageWriteParam param) throws IOException
  93:   {
  94:     int size;
  95:     int value;
  96:     int j;
  97:     int rowCount;
  98:     int rowIndex;
  99:     int lastRowIndex;
 100:     int[] bitmap;
 101:     size = (infoHeader.biWidth * infoHeader.biHeight) - 1;
 102:     rowCount = 1;
 103:     rowIndex = size - infoHeader.biWidth;
 104:     lastRowIndex = rowIndex;
 105:     ByteBuffer buf = ByteBuffer.allocate(size);
 106:     try
 107:       {
 108:         bitmap = new int[infoHeader.biWidth * infoHeader.biHeight];
 109:         PixelGrabber pg = new PixelGrabber((BufferedImage) image.getRenderedImage(),
 110:                                            0, 0, infoHeader.biWidth,
 111:                                            infoHeader.biHeight, bitmap, 0,
 112:                                            infoHeader.biWidth);
 113:         pg.grabPixels();
 114: 
 115:         for (j = 0; j < size; j++)
 116:           {
 117:             value = bitmap[rowIndex];
 118:             buf.put((byte) (value & 0xFF));
 119: 
 120:             if (rowCount == infoHeader.biWidth)
 121:               {
 122:                 rowCount = 1;
 123:                 rowIndex = lastRowIndex - infoHeader.biWidth;
 124:                 lastRowIndex = rowIndex;
 125:               }
 126:             else
 127:               rowCount++;
 128:             rowIndex++;
 129:           }
 130: 
 131:         buf.flip();
 132:         o.write(uncompress(infoHeader.biWidth, infoHeader.biHeight, buf));
 133:       }
 134:     catch (Exception wb)
 135:       {
 136:         wb.printStackTrace();
 137:       }
 138:     }
 139: 
 140: 
 141:   /**
 142:    * Uncompresses the image stored in the buffer.
 143:    *
 144:    * @param w - the width of the image
 145:    * @param h - the height of the image
 146:    * @param buf - the ByteBuffer containing the pixel values.
 147:    * @return byte array containing the uncompressed image
 148:    * @throws IOException if an error is encountered while reading
 149:    * buffer.
 150:    */
 151:   private byte[] uncompress(int w, int h, ByteBuffer buf) throws IOException
 152:   {
 153:     byte[] cmd = new byte[2];
 154:     byte[] data = new byte[w * h];
 155:     int offIn = 0;
 156:     int x = 0, y = 0;
 157: 
 158:     try
 159:       {
 160:         while ((x + y * w) < w * h)
 161:           {
 162:             try
 163:             {
 164:               buf.get(cmd);
 165:             }
 166:             catch (BufferUnderflowException e)
 167:             {
 168:               throw new IOException("Error reading compressed data.");
 169:             }
 170: 
 171:             if (cmd[0] == ESCAPE)
 172:               {
 173:                 switch (cmd[1])
 174:                   {
 175:                   case EOB:
 176:                     return data;
 177:                   case EOL:
 178:                     x = 0;
 179:                     y++;
 180:                     break;
 181:                   case DELTA:
 182:                     try
 183:                     {
 184:                       buf.get(cmd);
 185:                     }
 186:                     catch (BufferUnderflowException e)
 187:                     {
 188:                       throw new IOException("Error reading compressed data.");
 189:                     }
 190: 
 191:                     int dx = cmd[0] & (0xFF);
 192:                     int dy = cmd[1] & (0xFF);
 193:                     x += dx;
 194:                     y += dy;
 195:                     break;
 196: 
 197:                   default:
 198:                     int length = cmd[1] & (0xFF);
 199:                     int copylength = length;
 200: 
 201:                     length += (length & 1);
 202: 
 203:                     byte[] run = new byte[length];
 204: 
 205:                     try
 206:                     {
 207:                       buf.get(run);
 208:                     }
 209:                     catch (BufferUnderflowException e)
 210:                     {
 211:                       throw new IOException("Error reading compressed data.");
 212:                     }
 213: 
 214:                     System.arraycopy(run, 0, data, (x + w * (h - y - 1)),
 215:                                      copylength);
 216:                     x += copylength;
 217:                     break;
 218:                   }
 219:               }
 220:             else
 221:               {
 222:                 int length = cmd[0] & (0xFF);
 223:                 for (int i = 0; i < length; i++)
 224:                   data[(h - y - 1) * w + x++] = cmd[1];
 225:               }
 226:           }
 227:         return data;
 228:       }
 229:     catch (ArrayIndexOutOfBoundsException e)
 230:       {
 231:         throw new BMPException("Invalid RLE data.");
 232:       }
 233:   }
 234: }