resize.c

/**
 * copy.c
 *
 * Computer Science 50
 * Problem Set 4
 *
 * Copies a BMP piece by piece, just because.
 */
       
#include <stdio.h>
#include <stdlib.h>

#include "bmp.h"

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

    // remember filenames
    float n=atof(argv[1]);
    char* infile = argv[2];
    char* outfile = argv[3];

    // 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;
    }

    // write outfile's BITMAPFILEHEADER
    int paddingold =  (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
    int padding =  (4 - (int)(bi.biWidth * sizeof(RGBTRIPLE)*n) % 4) % 4;
    int biwidthold=bi.biWidth;
    bi.biWidth=(int)(bi.biWidth*n);
    bi.biHeight=(int)(bi.biHeight*n);
    bf.bfSize=54+((bi.biWidth*sizeof(RGBTRIPLE)+padding)*abs(bi.biHeight));
    bi.biSizeImage=(bi.biWidth*sizeof(RGBTRIPLE)+padding)*abs(bi.biHeight);
    
    fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outptr);

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

    // determine padding for scanlines
    

    // iterate over infile's scanlines
    int size=(int)(bi.biWidth/n*3);
    float ma[size];
    for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight/n; i++)
    {
        // iterate over pixels in scanline
        for (int q=0; q<n; q++)
        {
            for (int j = 0; j < bi.biWidth/n; j++)
            {
                // temporary storage
                RGBTRIPLE triple;
                // read RGB triple from infile
                if (q==0)
                {
                    fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
                    ma[(j*3)]=triple.rgbtBlue;
                    ma[(j*3)+1]=triple.rgbtGreen;
                    ma[(j*3)+2]=triple.rgbtRed;
                }
                // write RGB triple to outfile
                
                for (int a=0; a<n; a++)
                {
                    triple.rgbtBlue=ma[j*3];
                    triple.rgbtGreen=ma[(j*3)+1];
                    triple.rgbtRed=ma[(j*3)+2];
                    fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
                    if (n<1)
                    {
                        a++;
                        fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
                    }   
                }
                if (n<1)
                {
                    j++;
                }
            }
    
            // skip over padding, if any
            if (q==0)
            {
                fseek(inptr, paddingold, SEEK_CUR);
            }
    
            // then add it back (to demonstrate how)
            for (int k = 0; k < padding; k++)
            {
                fputc(0x00, outptr);
            }
            if (n<1)
            {
                q++;
                fseek(inptr, sizeof(RGBTRIPLE)*biwidthold+paddingold, SEEK_CUR);
            }
        }
        if (n<1)
        {
            i++;
        }
    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // that's all folks
    return 0;
}