A Simple Bitmap Writer

bitmapWriterV1.c

// check struct for gcc pragma pop push;
// http://stackoverflow.com/questions/11129138/reading-writing-bmp-files-in-c

#include <stdio.h>
#include <stdint.h> // uint8_t, uint16_t
#include <stdlib.h> // malloc()
#include <string.h>

#define HALF 2	// HALF WORD 2 bytes
#define WORD 4	// WORD      4 bytes
#define NUMBER_OF_COLOR_PLANES  1
#define BITMAP_INFO_HEADER_SIZE 40
#define COMPRESSION_STATE 0

/*
 * File Write , check this link : https://www.codingunit.com/c-tutorial-binary-file-io
 *
 */


/* For 54 byte header data
 *
 * http://blog.paphus.com/blog/2012/08/14/write-your-own-bitmaps/
 */
 #pragma pack(push,1)
typedef struct BitmapHeaderType {
	unsigned char      b0;                      // 0
	unsigned char      b1;                      // 1
	unsigned int       fullFileSize;            // 2...5
	unsigned int       reserved;                // 6...9
	unsigned int       pixelOffset;             // 10..13 HEADER SIZE
	unsigned int       bitmapInfoHeaderSize;    // 14..17 BITMAP INFO HEADER SIZE
	unsigned int       pixelWidth;              // 18..21 image width
	unsigned int       pixelHeight;             // 22..25 image height
	unsigned short int numberOfColorPlanes;     // 26..27 the number of color planes
	unsigned short int bitPerPixel;             // 28..29 24bit, 32bit, bit size
	unsigned int       compessionState;         // 30..33 compression state, 0 for disable compression
	unsigned int       sizeOfRawPixel;          // 34..37 size of pixel data including paddings (24 bit padding changes data section)
	unsigned int       horizontalResolution;    // 38..41 just leave 2835
	unsigned int       verticalResolution;      // 42..45 just leave 2835
	unsigned int       numberOfColors;          // 46..49 set 0 for default
	unsigned int       numberOfImportantColors; // 50..53 set 0 for default
} BitmapHeader;
#pragma pack(pop)

typedef struct PixelType{
	unsigned char blue;
	unsigned char green;
	unsigned char red;
}Pixel;

void handleBitmapHeader(BitmapHeader *header, int width, int height);
int closestMultipleOfFour(int num);
void writeToFile(unsigned char* bytes, int len, char fileName[]);


int main()
{
	BitmapHeader *header  = (BitmapHeader *)malloc(sizeof(BitmapHeader));	
	
	handleBitmapHeader(header, 800, 600);
	
	unsigned char *data   = (unsigned char *)malloc(header->sizeOfRawPixel);
	unsigned char *bitmap = (unsigned char *)malloc(header->fullFileSize);
	
	//// data
	//// pixel 1
	//*data = 0x00;
	//*(data+1) = 0x00;
	//*(data+2) = 0xff;
	//
	//// pixel 2
	//*(data+3) = 0xff;
	//*(data+4) = 0x00;
	//*(data+5) = 0x00;
	//
	//// pixel padding to multipe of 4
	//*(data+6) = 0x00;
	//*(data+7) = 0x00;
	
	int k = 0;
	for(int j = 0; j < 600; j++)
	{
		for(int i = j*800*3; i < (j+1)*800*3; i++)
			if(i%3 == k)
				*(data + i) = 0xff;
			else
				*(data + i) = 0x00;
			
		k = (k+1)%3;
	}

	
	
	// copy header to bitmap
	memcpy(bitmap, header, header->pixelOffset);
	
	// copy data to bitmap
	memcpy(bitmap+header->pixelOffset, data, header->fullFileSize);
	
	char fileName[] = "hello3.bmp";
	// write
	writeToFile((unsigned char *)bitmap , header->fullFileSize, fileName);
	
	free(header);
	free(data);
	free(bitmap);
	
	//PixelType black;
	//black.red = 0;
	//black.green = 0;
	//black.blue = 0;
	//
	//PixelType red;
	//black.red = 255;
	//black.green = 0;
	//black.blue = 0;
	
	
	//writeToFile((unsigned char *)header , sizeof(*header), fileName);
	
	

	
	return 0;
}

void handleBitmapHeader(BitmapHeader *header, int width, int height)
{
	//int numOfPixels = height * width;
	
	// Calculate row with padding
	int rowWithPadding = closestMultipleOfFour(width*3);
	int rawSize = height * rowWithPadding;
	printf("Row With Padding : %4d\n", rowWithPadding);
	printf("Raw Size : Decimal[%4d], Hex[%4x]\n", rawSize, rawSize);
	
	header->b0 = 'B';
	header->b1 = 'M';
	//header->fullFileSize = 0xFFFFFFFF;
	header->fullFileSize = rawSize + 54;
	header->reserved = 0x00000000;
	header->pixelOffset = 54;
	header->bitmapInfoHeaderSize = 40;
	//header->pixelWidth = 0x11223344;
	//header->pixelHeight = 0x55667788;
	header->pixelWidth = (unsigned int)width;
	header->pixelHeight = (unsigned int)height;
	header->numberOfColorPlanes = 1;
	header->bitPerPixel = 24;
	header->compessionState = 0;
	//header->sizeOfRawPixel = 0xAABBCCDD;
	header->sizeOfRawPixel = (unsigned int) rawSize;
	header->horizontalResolution = 0x2835;
	header->verticalResolution =   0x2835;
	header->numberOfColors = 0;
	header->numberOfImportantColors = 0;
}

int closestMultipleOfFour(int num)
{
	return (num + 3) & ~0x03;
}

void writeToFile(unsigned char* bytes, int len, char fileName[])
{
	FILE *filePtr;
	
	filePtr = fopen(fileName, "wb");	// wb for write binary
	
	if(!filePtr)
	{
		printf("ERROR::writeToFile()::Unable to open file : \"%s\"\n", fileName);
		return;
	}
	
	fwrite(bytes, len, 1, filePtr);
	
	fclose(filePtr);
}