resize.c

// Copies a BMP file

#include <stdio.h>
#include <stdlib.h>

#include "bmp.h"

int main(int argc, char *argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        fprintf(stderr, "Usage: copy infile outfile\n");
        return 1;
    }
    int n =     atoi(argv[1]);
    // remember filenames
    char *infile = argv[2];
    char *outfile = argv[3];

    // open input file
    FILE *inptr = fopen(infile, "r");
    if (inptr == NULL)
    {
        fprintf(stderr, "Could not open %s.\n", infile);
        return 2;
    }

    // open output file
    FILE *outptr = fopen(outfile, "w");
    if (outptr == NULL)
    {
        fclose(inptr);
        fprintf(stderr, "Could not create %s.\n", outfile);
        return 3;
    }

    // read infile's BITMAPFILEHEADER
    BITMAPFILEHEADER bf;
    fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);

    // read infile's BITMAPINFOHEADER
    BITMAPINFOHEADER bi;
    fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);

    // ensure infile is (likely) a 24-bit uncompressed BMP 4.0
    if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 ||
        bi.biBitCount != 24 || bi.biCompression != 0)
    {
        fclose(outptr);
        fclose(inptr);
        fprintf(stderr, "Unsupported file format.\n");
        return 4;
    }

    // make new headers
    BITMAPFILEHEADER bf2 = bf;
    BITMAPINFOHEADER bi2 = bi;

    // new width = old width * n
    bi2.biWidth = bi.biWidth *= n;
    // new height = old height * n
    bi2.biHeight = bi.biHeight *= n;

    int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    // new padding uses bi2 width
    int newPadding = (4 - (bi2.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

//   new biSizeIMage use new width, and new padding
    bi2.biSizeImage = ((sizeof(RGBTRIPLE) * bi2.biWidth) + newPadding) * abs(bi2.biHeight);

    // new bf size uses new biSize image and sizeof both new headers
    bf2.bfSize = bi2.biSizeImage + sizeof(bf2) + sizeof(bi2);

    // write outfile's BITMAPFILEHEADER
    fwrite(&bf2, sizeof(BITMAPFILEHEADER), 1, outptr);

    // write outfile's BITMAPINFOHEADER
    fwrite(&bi2, sizeof(BITMAPINFOHEADER), 1, outptr);

    // put pixels in an array
    RGBTRIPLE* arr = malloc(bi2.biWidth * sizeof(RGBTRIPLE));


    // iterate over infile's scanlines
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
    {
        // iterate over pixels in scanline
        for (int j = 0; j < bi.biWidth; j++)
        {
            // temporary storage
            RGBTRIPLE triple;

            // read RGB triple from infile
            fread(&triple, sizeof(RGBTRIPLE), 1, inptr);

            // write each triple into array above

            for(int k=0; k < n; k++){

                // write RGB triple to outfile N times- resize horiontally
                // fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);

                arr[j] = triple;

            }

        }

        // iterate n times, once equals a row
        for(int j = 0;j < n; j++){

        // for the width of the row, write the array items to the new file.
        printf("%d", bi.biWidth);
            for(int m = 0;m < bi.biWidth;m++){

                fwrite(&arr[m], sizeof(RGBTRIPLE), 1, outptr);

        // skip over padding, if any


                 // skip over padding, if any
                //  file to seek in; number to move cursor;from where- SEEK_CUR, SEEK_END, SEEk_SET
            //     fseek(inptr, padding, SEEK_CUR);

            //     // then add it back (to demonstrate how)
            //     for (int k = 0; k < padding; k++)
            //     {
            //         // loop over len of old padding, and write new padding
            //         fputc(newPadding, outptr);
            //     }
            }


                for (int k = 0; k < newPadding; k++)
            {
                // loop over len of old padding, and write new padding
                fputc(0x00, outptr);
            }
        }
        // fseek(inptr, padding, SEEK_CUR);

    }


    free(arr);
    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // success
    return 0;
}