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.awt.image.RenderedImage;
  41: import java.io.IOException;
  42: import java.nio.ByteBuffer;
  43: import java.nio.ByteOrder;
  44: 
  45: import javax.imageio.IIOImage;
  46: import javax.imageio.stream.ImageInputStream;
  47: import javax.imageio.stream.ImageOutputStream;
  48: 
  49: public class BMPFileHeader {
  50:     /** Header signature, always 'BM' */
  51:     private final static short bfType = 0x424d;
  52: 
  53:     /** Bitmap file size, in bytes. */
  54:     protected long bfSize;
  55: 
  56:     /** Offset from the beginning of the file to the bitmap data */
  57:     protected long bfOffBits;
  58: 
  59:     /** BITMAPFILEHEADER is 14 bytes */
  60:     public static final int SIZE = 14;
  61:     private static final int BITMAPINFOHEADER_SIZE = 40;
  62: 
  63:     /**
  64:      * Creates the header from an input stream, which is not closed.
  65:      *
  66:      * @throws IOException if an I/O error occured.
  67:      * @throws BMPException if the header was invalid
  68:      */
  69:     public BMPFileHeader(ImageInputStream in) throws IOException, BMPException {
  70:         byte[] data = new byte[SIZE];
  71: 
  72:         if (in.read(data) != SIZE)
  73:             throw new IOException("Couldn't read header.");
  74:         ByteBuffer buf = ByteBuffer.wrap(data);
  75: 
  76:         if(buf.getShort(0) != bfType)
  77:             throw new BMPException("Not a BMP file.");
  78: 
  79:         buf.order(ByteOrder.LITTLE_ENDIAN);
  80: 
  81:         // get size (keep unsigned)
  82:         bfSize = ((long)buf.getInt(2) & (0xFFFFFFFF));
  83: 
  84:         // Two reserved shorts are here, and should be zero,
  85:         // perhaps they should be tested to be zero, but I don't
  86:         // feel this strictness is necessary.
  87: 
  88:         bfOffBits = ((long)buf.getInt(10) & (0xFFFFFFFF));
  89:     }
  90: 
  91:     /**
  92:      * Creates the header from an output stream, which is not closed.
  93:      *
  94:      * @param out - the image output stream
  95:      * @param im - the image
  96:      * @throws IOException if an I/O error occured.
  97:      */
  98:   public BMPFileHeader(ImageOutputStream out, IIOImage im) throws IOException
  99:   {
 100:     RenderedImage img = im.getRenderedImage();
 101:     int w = img.getWidth();
 102:     int h = img.getHeight();
 103: 
 104:     bfOffBits = SIZE + BITMAPINFOHEADER_SIZE;
 105:     bfSize = ((w * h) * 3) + ((4 - ((w * 3) % 4)) * h) + bfOffBits;
 106: 
 107:     write(out);
 108:   }
 109: 
 110:     /**
 111:      * Writes the header to an output stream, which is not closed or flushed.
 112:      *
 113:      * @throws IOException if an I/O error occured.
 114:      */
 115:     public void write(ImageOutputStream out) throws IOException {
 116:         ByteBuffer buf = ByteBuffer.allocate(SIZE);
 117:         buf.putShort(0, bfType); // ID
 118:         buf.putInt(2, (int)(bfSize & (0xFFFFFFFF))); // size
 119:         buf.putInt(6, 0); // 4 reserved bytes set to zero
 120:         buf.putInt(7, (int)(bfOffBits & (0xFFFFFFFF))); // size
 121:         out.write(buf.array());
 122:     }
 123: 
 124:     /**
 125:      * Sets the file size
 126:      */
 127:     public void setSize(long size){
 128:         bfSize = size;
 129:     }
 130: 
 131:     /**
 132:      * Sets the bitmap offset within the file
 133:      */
 134:     public void setOffset(long offset){
 135:         bfOffBits = offset;
 136:     }
 137: 
 138:     /**
 139:      * Gets the file size
 140:      */
 141:     public long getSize(){
 142:         return bfSize;
 143:     }
 144: 
 145:     /**
 146:      * Gets the bitmap offset within the file
 147:      */
 148:     public long getOffset(){
 149:         return bfOffBits;
 150:     }
 151: }