reading header from BMP

[szcygan]

The header of a bmp file is supposed to be:

typedef struct
{
unsigned short bfType;
unsigned int bfSize;
unsigned short bfReserved1;
unsigned short bfReserved2;
unsigned int bfOffBits;
} BITMAPFILEHEADER;

I'm reading this header like this:

fread(&header, sizeof(BITMAPFILEHEADER), 1, fp)

and it seems to be working fine. The bfType is correct, but everything else is... not right. bfSize = 0 or 3 or something like that, bfOffBits is 7 digits long etc.. Is this maybe a problem with structure aligment, or something else?

Please help!

 

[Cagliostro]

try to see if bfType is 'BM' or 'MB'. If is 'MB' then there is some problems with number little/big endian formats.

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com

 

[szcygan]

Thanks Ion.

It is 'MB'.. How can I solve this problem? (I'm rather fresh with Visual C++)

 

[Cagliostro]

in this case you should invert each int and shortint

short int is 2 bytes, for example AB, change it to BA.
int or long is 4 bytes, for example ABCD, change it to DCBA. Use unions:

class inverter
{
public:
union
{
int x;
char c[4];
};
void invert()
{swap there the order of characetrs in c}
};
inverter a;
a.x = = younumber;
a.invert();
yournumebr = a.x;

Ion Filipski

ICQ: 95034075
AIM: IonFilipski
filipski@excite.com