Creating bmp file in C

Question

I am trying to create .bmp file (filled with one colour for testing purposes).

Here is code that I'm using:

#include <stdio.h>

#define BI_RGB 0

typedef unsigned int UINT;
typedef unsigned long DWORD;
typedef long int LONG;
typedef unsigned short WORD;
typedef unsigned char BYTE;

typedef struct tagBITMAPFILEHEADER {
    UINT bfType;
    DWORD bfSize;
    UINT bfReserved1;
    UINT bfReserved2;
    DWORD bfOffBits;
} BITMAPFILEHEADER;

typedef struct tagBITMAPINFOHEADER {
    DWORD biSize;
    LONG biWidth;
    LONG biHeight;
    WORD biPlanes;
    WORD biBitCount;
    DWORD biCompression;
    DWORD biSizeImage;
    LONG biXPelsPerMeter;
    LONG biYPelsPerMeter;
    DWORD biClrUsed;
    DWORD biClrImportant;
} BITMAPINFOHEADER;

typedef struct COLORREF_RGB
{
    BYTE cRed;
    BYTE cGreen;
    BYTE cBlue;
}COLORREF_RGB;

int main(int argc, char const *argv[])
{

    BITMAPINFOHEADER bih;

    bih.biSize = sizeof(BITMAPINFOHEADER);
    bih.biWidth = 600;
    bih.biHeight = 600;
    bih.biSizeImage = bih.biWidth * bih.biHeight * 3;
    bih.biPlanes = 1;
    bih.biBitCount = 24;
    bih.biCompression = BI_RGB;
    bih.biXPelsPerMeter = 2835;
    bih.biYPelsPerMeter = 2835;
    bih.biClrUsed = 0;
    bih.biClrImportant = 0;



    COLORREF_RGB rgb;
    rgb.cRed = 0;
    rgb.cGreen = 0;
    rgb.cBlue = 0;



    BITMAPFILEHEADER bfh;

    bfh.bfType = 0x424D;
    bfh.bfReserved1 = 0;
    bfh.bfReserved2 = 0;
    bfh.bfOffBits = sizeof(BITMAPFILEHEADER) + bih.biSize;
    bfh.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) +
        bih.biWidth * bih.biHeight * 4;


    FILE *f;
    f = fopen("test.bmp","wb");
    fwrite(&bfh, sizeof(BITMAPFILEHEADER), 1, f);
    fwrite(&bih, sizeof(BITMAPINFOHEADER), 1, f);

    int i,j;
    for(i = 0; i < bih.biHeight; i++)
    {
        for(j = 0; j < bih.biWidth; j++)
        {
            fwrite(&rgb,sizeof(COLORREF_RGB),1,f);
        }
    }

    fclose(f);

    return 0;
}

and jet every time I compile and run it I get error saying that its not valid BMP image. I double checked all values in multiple references and still can't find error here.

Did I misunderstood something and what am I doing wrong here?

Also not sure if important but I am using Ubuntu 14.04 to compile this.

EDIT

Found one more issue :

bfh.bfType = 0x424D;

should be

bfh.bfType = 0x4D42;

But still can't see image.

Answer 1

I believe your field sizes to be incorrect, try this

#pragma pack(push, 1)

typedef struct tagBITMAPFILEHEADER {
    WORD bfType;
    DWORD bfSize;
    WORD bfReserved1;
    WORD bfReserved2;
    DWORD bfOffBits;
} BITMAPFILEHEADER;

#pragma pack(pop)