fileHandler.c

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include "include/fileHandler.h"
#include "include/types.h"
#include "include/utils.h"

bmpFile *parseBmpFile(char *bmpPath)
{
    FILE *fd;
    if ((fd = fopen(bmpPath, "r")) == NULL)
    {
        fprintf(stderr, "Error: unable to open BMP file \"%s\"\n", bmpPath);
        return NULL;
    }

    bmpFile *bmp = malloc(sizeof(bmpFile));
    bmp->header = malloc(sizeof(bmpFileHeader));
    bmp->imageHeader = malloc(sizeof(bmpImageHeader));

    if (fread(bmp->header, 14, 1, fd) != 1)
    {
        perror("Unable to read BMP header");
        // TODO: free all
        return NULL;
    }

    if (fread(bmp->imageHeader, sizeof(bmpImageHeader), 1, fd) != 1)
    {
        perror("Unable to read BMP image header");
        // TODO: free all
        return NULL;
    }
    
    if (bmp->imageHeader->bitCount != BITS_PER_PIXEL)
    {
        fprintf(stderr, "Error: expected bits per pixel is %d\n", BITS_PER_PIXEL);
        // TODO: free all
        return NULL;
    }

    bmp->data = malloc(bmp->imageHeader->imageSize);

    if (fread(bmp->data, bmp->imageHeader->imageSize, 1, fd) != 1)
    {
        perror("Unable to read BMP image data");
        // TODO: free all
        return NULL;
    }

    return bmp;
}

void writeMessageToOutput(file *extractedFile, const char *outputFileName)
{
    char *fullOutputFileName = malloc(strlen(outputFileName) + strlen((char *)extractedFile->extension));
    fullOutputFileName = strcpy(fullOutputFileName, outputFileName);
    fullOutputFileName = strcat(fullOutputFileName, (char *) extractedFile->extension);

    FILE *fd = fopen(fullOutputFileName, "w+"); // reading necessary?
    fwrite(extractedFile->data, extractedFile->size, 1, fd);
    fclose(fd);

    free(fullOutputFileName);
}

void copyBmpData(FILE *file, rgbData *pixels, int img_size)
{
    for (int i = 0; i < img_size; i++)
    {
        rgbData BGR = pixels[i];
        unsigned char color[3] = {BGR.b, BGR.g, BGR.r};
        fwrite(color, 1, sizeof(color), file);
    }
}

void initFileHeader(bmpFileHeader *bfh, int file_size)
{
    memcpy(&(bfh->type), "BM", 2);
    bfh->size = file_size;
    bfh->reserved1 = 0;
    bfh->reserved2 = 0;
    bfh->offset = 0;
}

void initImageHeader(bmpImageHeader *bih, int ppm, int file_size, int width, int height)
{
    bih->headerSize = sizeof(*bih);
    bih->width = width;
    bih->height = height;
    bih->planes = 1;
    bih->bitCount = 24;
    bih->compression = 0;
    bih->imageSize = file_size;
    bih->ppmX = ppm;
    bih->ppmY = ppm;
    bih->colorsUsed = 0;
    bih->importantColors = 0;
}

void createBmpFile(char *file_name, int height, int width, rgbData *pixels)
{
    bmpImageHeader bih;
    bmpFileHeader bfh;
    // dpi a ppm https://www.wikiwand.com/en/Dots_per_inch
    int ppm = 96 * 39.375;
    int img_size = height * width;
    int file_size = HEADER_SIZE + 8 * img_size;
    initFileHeader(&bfh, file_size);
    initImageHeader(&bih, ppm, file_size, width, height);

    FILE *fp = fopen(file_name, "wb");
    fwrite(&bfh, 1, 14, fp);
    fwrite(&bih, 1, sizeof(bih), fp);
    copyBmpData(fp, pixels, img_size);

    return;
}