How to display Windows bitmap (.bmp)?

Hi,
I get the following message in my DOs box:

C:\Lewis\Listings>java BMPDecoder List.bmp
File size: 14406
Reserved: 0
Offset: 118
Width: 371
Height: 76
Planes: 1
BPP: 4
Bitmap size: 14288
Horiz resolution: 0
Vert resolution: 0
Number of Colors: 16
Number of Important Colors: 16
java.lang.ArrayIndexOutOfBoundsException: -1
        at BMPDecoder.decode4bit(BMPDecoder.java
        at BMPDecoder.decode(BMPDecoder.java:90)
        at BMPDecoder.<init>(BMPDecoder.java:27)
        at BMPDecoder.main(BMPDecoder.java:182)

Could you send me that image (list.bmp): walters@ct.net

It works on all my 4-bit images, but I'm sure there are bugs in it.

Oops, disregard my previous comment.  I'm pretty sure this should fix it (stupid mistake):

Change the following line in the decode4bit() method:

BEFORE:   idx=data>>4;
AFTER:    idx=(data>>4)&0x0f;

Sorry about that (only fails if a 4-bit image uses the 16th color).

Just FYI, if you look at the source for the JDK, it
has code for reading in .bmp files.  If you just
do a getImage(), it should work.

-Tony

Rembo,

Didn't work for me (beleive me, I wouldn't have written this if I could have answered "use getImage()").

Are you talking about sun.awt.image.XbmImageDecoder?  That's for X bitmaps, not the same as Windows bitmaps.

Hi Tony,
it works pretty well so far. It displays most of
my bitmaps.

Could you send me the BMP spec you talked about
earlier? I will try to figure out why it still
does not depict certain BMPs correctly. They
are displayed distorted (at a certain angle) and
with weird colors (looks like some kind of photo
negative).

My email is

utsch@pd.et-inf.uni-siegen.de

Regards, Lewis

I sent you the spec.

Here are your points. They are well deserved.

Lewis

Here are your points. They are well deserved.

Lewis

For anyone who may buy this as a <PAQ>, here are the required fixes:




  private void decode8bit()
  {
    for (int y=height-1; y>=0; y--) {
      for (int x=0; x<width; x++)
        pixels[y*width+x]=colormap[nextByte()&0xff];
      //skip padding so that lines begin on DWord boundaries:
      for (int x=0; x<4-width%4; x++)
        nextByte();
    }
  }

  private void decode24bit()
  {
    for (int y=height-1; y>=0; y--) {
      for (int x=0; x<width; x++)
        pixels[y*width+x]=0xff000000 + (nextByte()&0xff) + (nextByte()&0xff)*0x100 + (nextByte()&0xff)*0x10000;
      //skip padding so that lines begin on DWord boundaries:
      for (int x=0; x<width%4; x++)
        nextByte();
    }
  }