BMPSave.h

#pragma once
#include <cstdio>

const int BYTES_PER_PIXEL = 3; /// red, green, & blue
const int FILE_HEADER_SIZE = 14;
const int INFO_HEADER_SIZE = 40;



unsigned char* createBitmapFileHeader(int height, int stride)
{
	int fileSize = FILE_HEADER_SIZE + INFO_HEADER_SIZE + (stride * height);

	static unsigned char fileHeader[] = {
		0,0,	 /// signature
		0,0,0,0, /// image file size in bytes
		0,0,0,0, /// reserved
		0,0,0,0, /// start of pixel array
	};

	fileHeader[0] = (unsigned char)('B');
	fileHeader[1] = (unsigned char)('M');
	fileHeader[2] = (unsigned char)(fileSize);
	fileHeader[3] = (unsigned char)(fileSize >> 8);
	fileHeader[4] = (unsigned char)(fileSize >> 16);
	fileHeader[5] = (unsigned char)(fileSize >> 24);
	fileHeader[10] = (unsigned char)(FILE_HEADER_SIZE + INFO_HEADER_SIZE);

	return fileHeader;
}

unsigned char* createBitmapInfoHeader(int height, int width)
{
	static unsigned char infoHeader[] = {
		0,0,0,0, /// header size
		0,0,0,0, /// image width
		0,0,0,0, /// image height
		0,0,	 /// number of color planes
		0,0,	 /// bits per pixel
		0,0,0,0, /// compression
		0,0,0,0, /// image size
		0,0,0,0, /// horizontal resolution
		0,0,0,0, /// vertical resolution
		0,0,0,0, /// colors in color table
		0,0,0,0, /// important color count
	};

	infoHeader[0] = (unsigned char)(INFO_HEADER_SIZE);
	infoHeader[4] = (unsigned char)(width);
	infoHeader[5] = (unsigned char)(width >> 8);
	infoHeader[6] = (unsigned char)(width >> 16);
	infoHeader[7] = (unsigned char)(width >> 24);
	infoHeader[8] = (unsigned char)(height);
	infoHeader[9] = (unsigned char)(height >> 8);
	infoHeader[10] = (unsigned char)(height >> 16);
	infoHeader[11] = (unsigned char)(height >> 24);
	infoHeader[12] = (unsigned char)(1);
	infoHeader[14] = (unsigned char)(BYTES_PER_PIXEL * 8);

	return infoHeader;
}


void generateBitmapImage(const unsigned char* image, int width, int height, const char* imageFileName)
{
	int widthInBytes = width * BYTES_PER_PIXEL;

	unsigned char padding[3] = { 0, 0, 0 };
	int paddingSize = (4 - (widthInBytes) % 4) % 4;

	int stride = (widthInBytes)+paddingSize;

	FILE* imageFile = fopen(imageFileName, "wb");

	unsigned char* fileHeader = createBitmapFileHeader(height, stride);
	fwrite(fileHeader, 1, FILE_HEADER_SIZE, imageFile);

	unsigned char* infoHeader = createBitmapInfoHeader(height, width);
	fwrite(infoHeader, 1, INFO_HEADER_SIZE, imageFile);

	int i;
	for (i = 0; i < height; i++)
	{
		fwrite(image + (i * widthInBytes), BYTES_PER_PIXEL, width, imageFile);
		fwrite(padding, 1, paddingSize, imageFile);
	}

	fclose(imageFile);
}