Hi, I'm reading a bitmap manually to try and make a program that does steganography, but I can't read the file correctly. The headers I read come out completely messed up, and they fail the check to see if I'm reading a bitmap file or not (if (FileHeader.bfType != (int)"BM")). Please help.
#include <iostream>
#include <stdio.h>
using namespace std;
class BMP
{
public:
typedef struct
{
WORD bfType;
DWORD bfSize;
DWORD bfReserved;
DWORD bfOffBits;
} BMP_FILE_HEADER;
typedef struct
{
DWORD biSize;
LONG biWidth;
LONG biHeight;
WORD biPlanes;
WORD biBitCount;
DWORD biCompression;
DWORD biSizeImage;
LONG biXPelsPerMeter;
LONG biYPelsPerMeter;
DWORD biClrUsed;
DWORD biClrImportant;
} BMP_INFO_HEADER;
BMP_FILE_HEADER FileHeader;
BMP_INFO_HEADER InfoHeader;
unsigned char *Data;
// Methods
bool LoadBitmapFile(const char *Filename);
};
bool BMP::LoadBitmapFile(const char *Filename)
{
BMP Bitmap;
unsigned char *bitmap_Image;
FILE *File = NULL;
unsigned int ImageIdx = 0;
File = fopen(Filename,"rb");
if (!File)
return false;
// Read the file header
fread(&Bitmap.FileHeader, sizeof(BMP_FILE_HEADER), 1, File);
// Check if its a bitmap or not
if (FileHeader.bfType != (int)"BM")
return false;
// Read the info header
fread(&Bitmap.InfoHeader, sizeof(BMP_INFO_HEADER), 1, File);
// Store the data
memcpy((char*)&this->FileHeader, (char*)&Bitmap.FileHeader, sizeof(BMP_FILE_HEADER));
memcpy((char*)&this->InfoHeader, (char*)&Bitmap.InfoHeader, sizeof(BMP_INFO_HEADER));
// Move to the bitmap data
fseek(File, Bitmap.FileHeader.bfOffBits, SEEK_SET);
// Allocate memory
if (Bitmap.InfoHeader.biSizeImage != 0)
bitmap_Image = (unsigned char*)calloc(Bitmap.InfoHeader.biSizeImage, sizeof(unsigned char));
if (!bitmap_Image)
{
free(bitmap_Image);
fclose(File);
return false;
}
// Get RGB instead of BGR
for (ImageIdx=0; ImageIdx < Bitmap.InfoHeader.biSizeImage; ImageIdx+=3)
{
bitmap_Image[ImageIdx] = bitmap_Image[+2];
bitmap_Image[ImageIdx+2] = bitmap_Image[ImageIdx];
}
// Store the bitmap data
memcpy((unsigned char*)&this->Data, (unsigned char*)&bitmap_Image, Bitmap.InfoHeader.biSizeImage);
// Clean up and return
fclose(File);
return true;
};
int main(int argc, char **argv)
{
BMP bmp;
if (bmp.LoadBitmapFile("untitled.bmp"))
{
printf("UNTITLED.BMP\n\n");
cout << bmp.InfoHeader.biWidth << " by " << bmp.InfoHeader.biHeight;
}
else
cout << "ERROR!";
cin.ignore();
}
