Basic Objective
A windows BMP file is a common image format that Java does not handle. While BMP images are used only on windows machines, they are reasonably common. Reading these shows how to read complex structures in Java and
How to alter the byte order from the big endian order sale by java to the little endian order used by the windows and the intel processor.
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//
// this code WAS Taken and clean version
// javaworld tips and tricks column
//
Import
Java.awt.image;
Import
Java.awt.toolkit;
Import
Java.awt.image.MemoryImagesource;
Import
Java.io.fileinputstream;
Import
Java.io.ioException;
Import
Javax.swing.imageicon;
Import
Javax.swing.jframe;
Import
Javax.swing.jlabel;
Import
Javax.swing.jscrollpane;
//
// Really Just a Collection of Methods To Read A BMP File
//
public
Class Bmployader
{
// build an int from a byte array - converest Little to Big Endian
public
Static
Int constructint
Byte [] in,
INT offset {
INT RET =
Int in [Offset
3] &
0xFF);
Ret = (RET <<
8) |
Int in [Offset
2] &
0xFF);
Ret = (RET <<
8) |
Int in [Offset
1] &
0xFF);
Ret = (RET <<
8) |
Int in [Offset
0] &
0xFF);
Return (RET);
}
// build an int from a byte array - converest Little to Big Endian
// set high order bytes to 0xfff
public
Static
Int constructint3 (
Byte [] in,
INT offset {
int RET =
0xFF;
Ret = (RET <<
8) |
Int in [Offset
2] &
0xFF);
Ret = (RET <<
8) |
Int in [Offset
1] &
0xFF);
Ret = (RET <<
8) |
Int in [Offset
0] &
0xFF);
Return (RET);
}
// build an int from a byte array - conve port Little to Big Endianpublic
Static
Long Constructionlong
Byte [] in,
INT offset {
Long Ret = (("
Long) in [Offset
7] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
6] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
5] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
4] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
3] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
2] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
1] &
0xFF);
RET | = (RET <<
8) |
Long) in [Offset
0] &
0xFF);
Return (RET);
}
// build an double from a byte array - conve big little to big end
public
Static
Double constructdouble
Byte [] in,
INT offset {
Long Ret = Constructlong (in, offset);
Return (Double.longBitStodouble (RET));
}
// build an short from a byte array - Convert Little to Big Endian
public
Static
Short ConstructionShort
Byte [] in,
INT offset {
Short Ret =
SHORT)
Short) in [Offset
1] &
0xFF);
Ret =
Short) ((ret <<
8) |
SHORT)
Short) in [Offset
0] &
0xFF));
Return (RET);
}
// INTERNAL CLASS REPRESENTING A Bitmap HEADER STRUCTURE
// with code to read it from a file
Static
Class Bitmapheader {
public
Int nsize;
public
INT NBISIZE;
public
Int nwidth;
public
Int nHeiGHT;
public
Int nplanes;
public
Int nbitcount;
public
Int ncompression;
public
Int nsizeimage;
public
Int nxpm;
public
INT NYPM;
public
Int nclrused;
public
Int nclrimp;
// read in the bitmap header
public
Void Read
FileInputStream FS)
ThrowsioException
{
Final
Int bflen =
14;
// 14 Byte BitmapfileHeader
Byte bf [] =
New
BYTE [BFLEN];
fs.read (bf,
0, bflen);
Final
INT bilen =
40;
// 40-byte bitmapinfoheader
BYTE BI [] =
New
BYTE [BILEN];
fs.read (bi,
0, Bilen;
// Interperet Data. Nsize = constructint (BF,
2);
// system.out.println ("File Type IS:" (Char) BF [0] (CHAR) BF [1]);
// system.out.println ("SIZE OF FILE IS: NSize);
Nbisize = constructint (Bi,
2);
// system.out.println ("Size of BitmapInfoHeader IS:" Nbisize);
NWIDTH = Constructint (Bi,
4);
// system.out.println ("width is:" nwidth);
NHEIGHT = ConstructInt (Bi,
8);
// system.out.println ("Height IS:" NHEIGHT);
Nplanes = ConstructShort (Bi,
12);
// ((int) Bi [13] & 0xff) << 8) |
// (int) Bi [12] & 0xff;
// system.out.println ("Planes IS:" NPLANES);
Nbitcount = ConstructionShort (Bi,
14);
// ((int) Bi [15] & 0xff) << 8) |
// (int) BI [14] & 0xff;
// system.out.println ("Bitcount IS: NbitCount);
// Look for Non-Zero Values To Indicate Compression Ncompression = ConstructInt (Bi,
16);
// system.out.println ("Compression IS: NCompRESSION);
nsizeImage = constructint (Bi,
20);
// system.out.println ("SizeImage is:" nsizeImage);
NXPM = Constructint (Bi,
twenty four);
// System.out.println ("X-Pixels Per meter is:" NXPM);
NYPM = Constructint (BI,
28);
// system.out.println ("Y-Pixels Per meter is:" NYPM);
nclrused = constructint (Bi,
32);
// system.out.println ("Colors Used Are: NCLRUSED);
Nclrimp = constructint (BI,
36);
// system.out.println ("Colors Important Are: NClrim);
}
}
public
Static
Image read
FileInputStream FS)
{
Try {
BitmapHeader BH =
New bitmapheader ();
Bh.read (fs);
IF (bh.nbitcount ==
twenty four)
Return (READMAP24 (FS, BH));
IF (bh.nbitcount ==
32)
Return (READMAP32 (FS, BH));
IF (bh.nbitcount ==
8)
Return (READMAP8 (FS, BH));
fs.close ();
}
Catch (
IOEXCEPTION E) {
// system.out.println ("Caught Exception in LoadBitMap!");
Return
NULL);
}
/ ** * * Readmap24 Internal routine to read the bytes in a 24 bit bitmap * * * * arguments: * * fs - file stream * * BH - Header struct * * returns: * * Image Object, Be Sure to Check for Image) NULL !!!! * * * * /
protected
Static
Image readmap32
FileInputStream Fs, BitmapHeader BH)
Throws
IOEXCEPTION
{
Image image;
// no Palatte Data for 24-bit Format But Scan Lines Are
// Padded Out to Even 4-byte boundaries.
INT xwidth = Bh.nsizeiMage / Bh.NHEIGHT;
Int nData [] =
New
int [BH.NHEIGHT * BH.NWIDTH];
Byte brgb [] =
New
Byte [Bh.NWIDTH *
4 * Bh.nHeight];
fs.read (brgb,
0, BH.NWIDTH *
4 * BH.NHEIGHT);
INT NINDEX =
0;
FOR
INT j =
0; j { FOR INT i = 0; i { NData [Bh.NWIDTH * (BH.NHEIGHT - J - 1) i] = constructint3 ( BRGB, NINDEX); NINDEX = 4; } } Image = Toolkit.getDefaultToolkit (). CreateImage ( New MemoryImagesource (Bh.NWIDTH, BH.NHEIGHT, NDATA, 0, BH.NWIDTH)); fs.close (); Return (Image); } / ** * * Readmap24 Internal routine to read the bytes in a 24 bit bitmap * * * * arguments: * * fs - file stream * * BH - Header struct * * returns: * * Image Object, Be Sure to Check for Image) NULL !!!! * * * * / protected Static Image readmap24 ( FileInputStream Fs, BitmapHeader BH) Throws IOEXCEPTION { Image image; // no Palatte Data for 24-bit Format But Scan Lines Are // Padded Out to Even 4-byte boundaries. INT NPAD = (Bh.nsizeImage / Bh.NHEIGHT) - BH.NWIDTH * 3; Int nData [] = New int [BH.NHEIGHT * BH.NWIDTH]; Byte brgb [] = New Byte [(Bh.NWIDTH NPAD) * 3 * Bh.nHeight]; fs.read (brgb, 0, (BH.NWIDTH NPAD) * 3 * bh.nheight); INT NINDEX = 0; FOR INT j = 0; j { FOR INT i = 0; i { NData [Bh.NWIDTH * (BH.NHEIGHT - J - 1) i] = constructint3 ( BRGB, NINDEX); NINDEX = 3; } NINDEX = NPAD; } Image = Toolkit.getDefaultToolkit (). CreateImage ( New MemoryImagesource (Bh.NWIDTH, BH.NHEIGHT, NDATA, 0, BH.NWIDTH)); fs.close (); Return (Image); } / ** * * readmap8 Internal routine to read the bytes in a 8 bitmap * * * * arguments: * * fs - file stream * * BH - Header struct * * returns: * * Image Object, Be Sure to Check for Image) NULL !!!! * * * * / protected Static Image ketmap8 FileInputStream Fs, BitmapHeader BH) Throws IOEXCEPTION { Image image; // Have to Determine The Number of Colors, The Clrsused // Parameter Is Dominant if it is greater tour Zero. IF // Zero, Calculate Colors Based on BitsPixel.Int nnumcolors = 0; IF (Bh.NCLRUSED> 0) { Nnumcolors = BH.NCLRUSED; } Else { Nnumcolors = 1 & 0xFF) << Bh.nbitcount; } // system.out.println ("The Number of Colors Is" Nnumcolors); // Some Bitmaps do not home the sizeimage field calculate // Ferret Out these Cases and fix 'em. IF (Bh.nsizeImage == 0) { Bh.nsizeImage = (((Bh.nWidth * Bh.nbitcount) 31) & ~ 31) >> 3); Bh.nsizeImage * = BH.NHEIGHT; // system.out.println ("NSIZEIMAGE (Backup) is" nsizeImage); } // read The Palatte Colors. Int npalette [] = New Int [nnumcolors]; Byte bpalette [] = New Byte [nnumcolors * 4]; fs.read (bPalette, 0, nnumcolors * 4); INT NINDEX8 = 0; FOR INT n = 0; n { NPALETTE [N] = ConstructInt3 (BPALETTE, NINDEX8); NINDEX8 = 4; } // read the image data (actual component INTO THE PALETTE) // Scan Lines Are Still Padded Out To Even 4-Byte // boundaries. INT NPAD8 = (Bh.nsizeImage / Bh.NHEIGHT) - BH.NWIDTH; // system.out.println ("NPAD IS:" NPAD8); Int nData8 [] = New Int [Bh.nWidth * Bh.nHeight]; Byte bdata [] = New Byte [(Bh.nWidth NPAD8) * BH.NHEIGHT]; Fs.read (BData, 0, (Bh.nWidth NPAD8) * BH.NHEIGHT); NINDEX8 = 0; FOR INT J8 = 0; J8 { FOR INT i8 = 0; I8 { NDATA8 [BH.NWIDTH * (BH.NHEIGHT - J8 - J8 - 1) i8] = NPALETTE [(( Int) BData [Nindex8] & 0xFF)]; NINDEX8 ; } NINDEX8 = NPAD8; } Image = Toolkit.getDefaultToolkit (). CreateImage ( New MemoryImagesource (Bh.NWIDTH, BH.NHEIGHT, NDATA8, 0, BH.NWIDTH)); Return (Image); } / ** * * load method - See read for details * * * * arguments: * * sdir and sfile all the result of the filedialog () * getdirectory () and getfile () methods. * * * * Returns: * * Image Object, Be Sure To Check for (Image) NULL !!!! * * * * / public Static Image load String SDIR, String sfile) { Return (LOAD (SDIR SFILE)); } / ** * * load method - See read for details * * * * arguments: * * sdir - full path name * * * * returns: * * Image Object, be sure to check for (image) null !!!! * * * * / public Static Image load String SDIR) { Try { FileInputStream Fs = New FileInputStream (SDIR); Return (READ (FS)); } Catch ( IOEXCEPTION EX) { Return NULL); } } public Static Void main String [] ARGS) Throws IOEXCEPTION { IF (args.length == 0) { System.out.println ( "USAGE> JAVA BMPLOADER ImageFile.BMP"); SYSTEM.EXIT ( 0); } FileInputStream in = New FileInputStream (Args [ 0]); Image theimage = = read (in); JFrame theframe = New JFrame (Args [ 0]); Jlabel thelabel = New Jlabel New Imageicon (TheImage); Theframe.getContentPane (). Add ( New Jscrollpane (TheLabel); Theframe.setsize 300, 300); Theframe.setvisible True); } // end class bmploader}
