Resize check50 results pset4

Question

Thought I had done this one, but getting errors with check50, here is my code:

/** *resize.c * * Computer Science 50 * Problem Set 4 * * Resizes a BMP file by a factor of n. */

include

include

include "bmp.h"

int main(int argc, char* argv[]) { // ensure proper usage if (argc != 4) { printf("Usage: ./resize integer infile outfile\n"); return 1; }

// remember filenames
char* infile = argv[2];
char* outfile = argv[3];

// what is the scale input by user
int n = atoi(argv[1]);

// make sure input is psotive and between 0 and 100
if (n < 0 || n > 100)
{
    printf("Please input a positive integer between 0 and 100");
    return 5;
}

// open input file 
FILE* inptr = fopen(infile, "r");
if (inptr == NULL)
{
    printf("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;
}

// Need to declare new outfile headers
BITMAPFILEHEADER new_bf = bf;
BITMAPINFOHEADER new_bi = bi;


// find out new width and height
new_bi.biWidth = bi.biWidth * n;
new_bi.biHeight = bi.biHeight * n;

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

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

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

// new padding
int new_padding = (4 - (new_bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

// new size of image.
new_bi.biSizeImage = (new_bi.biWidth * sizeof(RGBTRIPLE) + new_padding) 
* abs(new_bi.biHeight);

// new size of the file
new_bf.bfSize = new_bi.biSizeImage + 54; 

// iterate over infile's scanlines
for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
{
    for(int k = 0; k < n; k++)
    { 

     // 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 i = 0; i < n; i++)
            {
                fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
            }

         }

        // skip over padding, if any
        fseek(inptr, padding, SEEK_CUR);


        // then add it back (to demonstrate how)
        for (int k = 0; k < new_padding; k++)
        {
            fputc(0x00, outptr);
        }


        fseek(inptr, -(bi.biWidth * sizeof(RGBTRIPLE)
        + padding), SEEK_CUR);  

    }

    fseek(inptr, bi.biWidth * sizeof(RGBTRIPLE) + padding, SEEK_CUR);
}

// close infile
fclose(inptr);

// close outfile
fclose(outptr);

// that's all folks
return 0;

}

Spent ages on it now and looking for some advice as to where I'm going wrong, here is the check50 results and again any help would be much appreciated:

:) resize.c and bmp.h exist

:) resize.c compiles :) doesn't resize 1x1-pixel BMP when n is 1

:( resizes 1x1-pixel BMP to 2x2 correctly when n is 2

:( resizes 1x1-pixel BMP to 3x3 correctly when n is 3

:( resizes 1x1-pixel BMP to 4x4 correctly when n is 4

:( resizes 1x1-pixel BMP to 5x5 correctly when n is 5

:( resizes 2x2-pixel BMP to 4x4 correctly when n is 2

Answer 1

Wouldn't it work better if you wrote out the headers after you calculate the new new_bf.bfSize and new_bi.biSizeImage ?

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