Parsing the Windows BMP format ???

[Christer]

Hi all,

I have some serious trouble parsing information from
a graphics file in windows bmp format (256 colors).
I have managed to open the file but when i try to read
any of the data I always get 0.
If I open the file in binary format in visaual c++ I
can see that the file is correct and it starts with the
signature BM.

As I understand it, the (256 color) bmp consists of the 3 headers structs

BITMAPFILEHEADER, BITMAPINFOHEADER, RGBQUAD and then the actual picture data.

I suspect this is were something goes wrong:

...
ifstream fIn;
BITMAPFILEHEADER fileHeader;

...

fIn.read((char*) &fileHeader, sizeof(BITMAPFILEHEADER));

However my struct fileHeader is terrible empty...eventhough the above
statement should copy sizeof(BITMAPFILEHEADER) bytes to the struct fileHeader...right???

As I am a bit new to c++ I wonder how the reading should be done
since the way I do it seems to be wrong.

Hoping for a bit of help here...

Best Regards,
Christer

[hk_mp5kpdw]

Are you opening the file in binary mode? If not then do so and try again.

[Christer]

Yes, I've opened the file in binary mode.
The problem is still there...
/Christer

[christer]

hi again,

here is the error check when opening the file:

fIn.open("test.bmp", ios::binary);
if (!fIn.is_open()) {
cout << "Failed to open the file " << theFileName <<"\r\n";
return false;
}

Wen running the program the error message does not show so the opening should be ok.

/Christer