resizemore.c

// Resizes a BMP file

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

#include "bmp.h"


// Use debug50 if confused
// check with check50
// look at style with style50




int main(int argc, char *argv[])
{
    // ensure proper usage
    if (argc != 4)
    {
        fprintf(stderr, "Usage: size-factor infile outfile\n");
        return 1;
    }

    // Create size factor from input
    // Note - have changed the below from int n and atoi to double n and atof
    double n_double = atof(argv[1]);

    // Check n is greater than 1 and less than 100

    if (n_double < 0 || n_double > 100)
    {
        fprintf(stderr, "Usage: n needs to be positive number less than 100\n");
        return 1;
    }

    // Save n

    double n_save = n_double;

    // Separate the integer part of n

    int int_n = n_double;

    // Separate the remainder part of n

    double n_remain = n_double - int_n;

    // Declare n and the special nx for use for floats less than 1

    int n = 0;
    double nx = 0;

    // new triage
    // floats between 0.5 and 0.999... are rounded up to one
    // Idea - could increase this limit to 0.75, so 0.5 is still considered 0.5!
    // floats between 0 and 0.5 are rounded to 0.5
    // numbers 2.01 to 2.49 are rounded down to 2
    // numbers like 2.5 to 2.99 are rounded up to 3

    // for numbers between 0 and 1
    if (int_n == 0)
    {
        // if over 0.5, round to 1
        if (n_remain > 0.5)
        {
            n = 1;
        }
        // if 0.5 or less, round to 0.5
        else if (n_remain <= 0.5)
        {
            nx = 0.5;
        }
    }
    // if remainder is between 0 and 0.5, round down to whole number
    else if (n_remain > 0 && n_remain < 0.5)
    {
        n = int_n;
    }
    // if remainder is equal to or over 0.5 round up to whole number
    else if (n_remain >= 0.5)
    {
        n = int_n + 1;
    }
    // if no remainder, set n as whole number
    else if (n_remain == 0)
    {
        n = int_n;
    }

    // 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;
    }

    // Save width and height (height saved as positive number)
    int width_save = bi.biWidth;

    int height_save = abs(bi.biHeight);

    int sizeimage_save = bi.biSizeImage;

    int size_save = bf.bfSize;

    // Padding save
    int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

    int padding_save = padding;

    // Triage point

    if (nx == 0)

    {

        // Change width and height based on n
        bi.biWidth = bi.biWidth * n;

        bi.biHeight = bi.biHeight * n;

        // Adjust new padding using new bi.biWidth
        padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

        // Create new Size Image and size
        bi.biSizeImage = ((sizeof(RGBTRIPLE) * bi.biWidth) + padding) * abs(bi.biHeight);

        bf.bfSize = bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

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

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

        // iterate over infile's scanlines
        // Change the limit in this condition from new height to height save
        for (int i = 0; i < height_save; i++)
        {
            // iterate over pixels in scanline
            // Use width_save as the limit rather than bi.biWidth
            int loop_limit = n - 1;

            for (int x = 0; x < loop_limit; x++)
            {
                for (int j = 0; j < width_save; 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++)
                    {
                        fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
                    }
                }

                // Insert end of line padding
                for (int k = 0; k < padding; k++)
                {
                    fputc(0x00, outptr);
                }

                // Create offset, old width in pixels converted to bytes
                int offset = -3 * width_save;

                // Move cursor
                fseek(inptr, offset, SEEK_CUR);
            }

            for (int j = 0; j < width_save; 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++)
                {
                    fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
                }
            }

            // Insert end of line padding
            for (int k = 0; k < padding; k++)
            {
                fputc(0x00, outptr);
            }

            // final row write

            // skip over padding, if any
            // Replace padding in fseek with padding_save
            fseek(inptr, padding_save, SEEK_CUR);
        }
    }

    // Branch for 0.5's etc

    else if (n == 0)

    {
        // the pre-process triage for even or odd widths and heights
        // even width
        if (width_save % 2 == 0)
        {
            bi.biWidth = bi.biWidth * 0.5;
        }
        // odd width
        else if (width_save % 2 != 0)
        {
            bi.biWidth = (bi.biWidth - 1) * 0.5;
        }
        // even height
        if (height_save % 2 == 0)
        {
            bi.biHeight = bi.biHeight * 0.5;
        }
        // odd height
        else if (height_save % 2 != 0)
        {
            // + rather than - because biheight is negative
            bi.biHeight = (bi.biHeight + 1) * 0.5;
        }

        {
            // The Process
            // make height positive

            int absolute_height_new = abs(bi.biHeight);

            // Adjust new padding using new bi.biWidth
            padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;

            // Create new Size Image and size
            bi.biSizeImage = ((sizeof(RGBTRIPLE) * bi.biWidth) + padding) * abs(bi.biHeight);

            bf.bfSize = bi.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER);

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

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

            // make offset, the distance (in bytes) the cursor has to move forward after store 2 and before store 3
            int offset = (3 * (width_save - 2)) + padding_save;

            // make reset, the distance (in bytes) the cursor has to move backwards after store 4 to be in position for the next loop
            int reset = (3 * width_save) + padding_save;

            // make deset, the distance in bytes the cursor has to move forward on the final turn of each row
            int deset = reset + padding_save;

            for (int x = 0; x < absolute_height_new; x++)
            {
                for (int i = 0; i < bi.biWidth; i++)
                {
                    // temp storage for 1
                    RGBTRIPLE store1;

                    // read RGB triple from infile
                    fread(&store1, sizeof(RGBTRIPLE), 1, inptr);

                    RGBTRIPLE store2;

                    fread(&store2, sizeof(RGBTRIPLE), 1, inptr);

                    fseek(inptr, offset, SEEK_CUR);

                    RGBTRIPLE store3;

                    fread(&store3, sizeof(RGBTRIPLE), 1, inptr);

                    RGBTRIPLE store4;

                    fread(&store4, sizeof(RGBTRIPLE), 1, inptr);

                    // take average of store 1-4

                    RGBTRIPLE store_average;

                    store_average.rgbtBlue = (store1.rgbtBlue + store2.rgbtBlue + store3.rgbtBlue + store4.rgbtBlue) / 4;
                    store_average.rgbtGreen = (store1.rgbtGreen + store2.rgbtGreen + store3.rgbtGreen + store4.rgbtGreen) / 4;
                    store_average.rgbtRed = (store1.rgbtRed + store2.rgbtRed + store3.rgbtRed + store4.rgbtRed) / 4;

                    // write the pixel
                    fwrite(&store_average, sizeof(RGBTRIPLE), 1, outptr);

                    // put cursor to start of new position
                    fseek(inptr, - reset, SEEK_CUR);

                }

                // Insert end of line padding
                for (int k = 0; k < padding; k++)
                {
                    fputc(0x00, outptr);
                }

                // re-reset cursor
                fseek(inptr, deset, SEEK_CUR);
            }

        }

    }

    // close infile
    fclose(inptr);

    // close outfile
    fclose(outptr);

    // success
    return 0;
}