Resize - version 1.0

[Alexico1969]

// resizes 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: resize number infile outfile\n");
return 1;
}

// remember filenames

char *infile = argv[2];
char *outfile = argv[3];

// remember enlargement factor

int n = atoi(argv[1]);

n+=0;

// 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;
}

//---- here I will have to put some code to update the file size, image size, width and the height

int padding;

//padding = bi.biSizeImage - (bi.biWidth*bi.biHeight);


bi.biWidth *= n;
bi.biHeight *= n;

padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

bi.biSizeImage = ((sizeof(RGBTRIPLE) * bi.biWidth) + padding) *abs(bi.biHeight);
bf.bfSize = bi.biSizeImage+sizeof(BITMAPFILEHEADER)+sizeof(BITMAPINFOHEADER);



//---- end of my update code


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

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

// determine padding for scanlines
padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

int oldPadding = padding;
oldPadding +=0;

// 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 RGB triple to outfile
            for (int l = 0; l < n; l++)  // for loop to multiply WIDTH
            {
                fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);

                padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

                // skip over padding, if any
                fseek(inptr, padding, SEEK_CUR);
                // then add it back (to demonstrate how)
                for (int k = 0; k < padding; k++)
                {
                    //fputc(0x00, outptr);
                }


            }


        }


}

// close infile
fclose(inptr);

// close outfile
fclose(outptr);

// success
return 0;

}