Thread: Manually Loading Bitmap Files

Hello, I was wondering if guys could help me out here, im trying to manually a load a bitmap file in a C++ program but am a little confused. After searching through various tutorials on this subject I dont seem to be doing anything wrong but for some reason the values I am getting in my bitmap headers seem to be wrong (or maybe its just me).

Here is the code i have to read a bitmap, admitedly it is not complete as it only opens the file and reads in to my "custom" BitmapFileHeader and BitmapInfoHeader structures.

Code:

 //structure to contain bitmap file header information. It is the same as the win32 version except its my own.. if that makes sense
struct BitmapFileHeader {
	unsigned short	Type;
	unsigned int	Size;
	unsigned short	Reserved1;
	unsigned short	Reserved2;
	unsigned int	OffBits;
};

struct BitmapInfoHeader {
	unsigned int	Size;
	long		Width;
	long		Height;
	unsigned short	Planes;
	unsigned short	BitCount;
	unsigned int	Compression;
	unsigned int	SizeImage;
	long		XPelsPerMeter;
	long		YPelsPerMeter;
	unsigned int	ClrUsed;
	unsigned int	ClrImrportant;
};

// Read bitmap file
void Bitmap::Read( const char* file )
{
	// open file for reading
	std::ifstream f( file, std::ios::binary );
	if ( !f.is_open( ) )
	{
		std::cout << "Error: File not found.";
		f.close( );
	}

	// read in the file and info headers
	f.read( reinterpret_cast<char*>(&mFileHeader), sizeof( BitmapFileHeader ) );
	f.read( reinterpret_cast<char*>(&mInfoHeader), sizeof( BitmapInfoHeader ) );
}

Here is the list of values that shows up when "stepping through" my code with the vs debugger:

mFileHeader.Type = 19778 < (Thats probably the only value that looks correct to me.. when cast into char* it produces "BM")
mFileHeader.Size = 0
mFileHeader.Reserved1 = 0
mFileHeader.Reserved2 = 54
mFileHeader.OffBits = 2621440

mInfoHeader.Size = 131072
mInfoHeader.Width = 131072
mInfoHeader.Height = 65536
mInfoHeader.Planes = 24
mInfoHeader.BitCount = 0
mInfoHeader.Compression = 1048576
mInfoHeader.SizeImage = 0
mInfoHeader.XPelsPerMeter = 0
mInfoHeader.YPelsPerMeter = 0
mInfoHeader.ClrUsed = 0
mInfoHeader.ClrImrportant = 0

Im not sure but i think the compression might be the problem, however i did try another type of .bmp that had compression 0 but still had the same problems so maybe not (and im guessing compression only deals with the actual data, not the headers).

Anywho, Thanks in advance.
~CC


PS: The image I am loading is a simple 2x2 24-bit .bmp created with windows 7 version of paint. Unless im a mistaken the mInfoHeader.Width/Height should be 2 x 2
not 131072x65536, you get my point :P