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/**
* resize.c
*
* Computer Science 50
* Problem Set 4
*
* Resizes the file whose name is passed to it as a commandline argument.
*/
#include <stdio.h>
#include <stdlib.h>
#include "bmp.h"
int main(int argc, char* argv[])
{
// ensure proper usage
if (argc != 4)
{
printf("Usage: ./resize n infile outfile\n");
return 1;
}
// remember filenames
char* infile = argv[2];
char* outfile = argv[3];
// change n into a number so we can use it as such
int n = atoi(argv[1]);
if (n <= 0 || n > 100)
{
printf("The value provided as the size must be that of a positive integer less than or equal to 100!\n");
return 2;
}
// open input file
FILE* inptr = fopen(infile, "r");
if (inptr == NULL)
{
printf("Could not open %s.\n", infile);
return 3;
}
// open output file
FILE* outptr = fopen(outfile, "w");
if (outptr == NULL)
{
fclose(inptr);
fprintf(stderr, "Could not create %s.\n", outfile);
return 4;
}
// 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;
}
//remember the old padding
int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
// remember dimensions of resized image
int img_height = bi.biHeight;
int img_width = bi.biWidth;
// calculate dimensions of resized image
bi.biHeight *= n;
bi.biWidth *= n;
int resized_height = bi.biHeight;
int resized_width = bi.biWidth;
// determine scanline padding
int new_padding = (4 - (resized_width * sizeof(RGBTRIPLE)) % 4) % 4;
// update header info
bi.biSizeImage = ((resized_width * sizeof(RGBTRIPLE) + new_padding) * abs(resized_height));
bf.bfSize = bi.biSizeImage + (sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER));
// 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
for (int i = 0, biHeight = abs(img_height); i < biHeight; i++)
{
// iterate over pixels in scanline
for (int j = 0; j < img_width; j++)
{
// temporary storage
RGBTRIPLE triple;
// read RGB triple from infile
fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
for (int index = 0; index <= n - 1; index++)
{
fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
}
}
// add new padding (if any must be added)
for (int k = 0; k < new_padding; k++)
{
fputc(0x00, outptr);
}
// skip over old padding, if any
fseek(inptr, padding, SEEK_CUR);
// iterate over images' widths and heights to resize vertically
for (int l = 0; l < img_width; l++)
{
// storage for the triples data
RGBTRIPLE triple;
// read from the infile and store in triple
fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
for (int m = 0; m < biHeight; m++)
{
for (int index = 0; index <= n - 1; index++)
{
fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
}
}
for (int k1 = 0; k1 < new_padding; k1++)
{
fputc(0x00, outptr);
}
fseek(inptr, -padding, SEEK_CUR);
}
}
// close infile
fclose(inptr);
// close outfile
fclose(outptr);
// that's all folks
return 0;
}
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