libjava/classpath/gnu/javax/imageio/bmp/BMPFileHeader.java

   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 }
 152
 153