Source for gnu.javax.imageio.bmp.BMPFileHeader

   1: /* BMPFileHeader.java --
   2:    Copyright (C)  2005  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: package gnu.javax.imageio.bmp;
  39: 
  40: import java.io.IOException;
  41: import javax.imageio.stream.ImageInputStream;
  42: import java.io.OutputStream;
  43: import java.nio.ByteBuffer;
  44: import java.nio.ByteOrder;
  45: 
  46: public class BMPFileHeader {
  47:     /** Header signature, always 'BM' */
  48:     private final static short bfType = 0x424d;
  49: 
  50:     /** Bitmap file size, in bytes. */
  51:     private long bfSize;
  52:     
  53:     /** Offset from the beginning of the file to the bitmap data */
  54:     private long bfOffBits;
  55: 
  56:     /** BITMAPFILEHEADER is 14 bytes */
  57:     public static final int SIZE = 14;
  58: 
  59:     /**
  60:      * Creates the header from an input stream, which is not closed.
  61:      * @throws IOException if an I/O error occured.
  62:      * @throws BMPException if the header was invalid
  63:      */
  64:     public BMPFileHeader(ImageInputStream in) throws IOException, BMPException {
  65:         byte[] data = new byte[SIZE];
  66: 
  67:     if (in.read(data) != SIZE)
  68:         throw new IOException("Couldn't read header.");
  69:     ByteBuffer buf = ByteBuffer.wrap(data);
  70: 
  71:     if(buf.getShort(0) != bfType)
  72:         throw new BMPException("Not a BMP file.");
  73: 
  74:     buf.order(ByteOrder.LITTLE_ENDIAN);
  75: 
  76:     // get size (keep unsigned)
  77:     bfSize = ((long)buf.getInt(2) & (0xFFFFFFFF));
  78: 
  79:     // Two reserved shorts are here, and should be zero,
  80:     // perhaps they should be tested to be zero, but I don't
  81:     // feel this strictness is necessary.
  82:     
  83:     bfOffBits = ((long)buf.getInt(10) & (0xFFFFFFFF));
  84:     }
  85: 
  86:     /**
  87:      * Writes the header to an output stream, which is not closed or flushed.
  88:      * @throws IOException if an I/O error occured.
  89:      */
  90:     public void write(OutputStream out) throws IOException {
  91:     ByteBuffer buf = ByteBuffer.allocate(SIZE);
  92:     buf.putShort(0, bfType); // ID
  93:     buf.putInt(2, (int)(bfSize & (0xFFFFFFFF))); // size
  94:     buf.putInt(6, 0); // 4 reserved bytes set to zero
  95:     buf.putInt(2, (int)(bfOffBits & (0xFFFFFFFF))); // size
  96:     out.write(buf.array());
  97:     }
  98:     
  99:     /**
 100:      * Sets the file size
 101:      */
 102:     public void setSize(long size){
 103:     bfSize = size;
 104:     }
 105: 
 106:     /**
 107:      * Sets the bitmap offset within the file
 108:      */
 109:     public void setOffset(long offset){
 110:     bfOffBits = offset;
 111:     }
 112: 
 113:     /**
 114:      * Gets the file size
 115:      */
 116:     public long getSize(){
 117:     return bfSize;
 118:     }
 119: 
 120:     /**
 121:      * Gets the bitmap offset within the file
 122:      */
 123:     public long getOffset(){
 124:     return bfOffBits;
 125:     }
 126: }
 127: