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/**
* resize.c
*
* Computer Science 50
* Problem Set 4
*
* resizes a BMP. Based on cs50 copy.c
*/
#include <stdio.h>
#include <stdlib.h>
#include <math.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 and size
int n = atoi(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;
}
/**save values of current header
LONG oldHeight = bi.biHeight;
LONG oldWidth = bi.biWidth;
*/
//establish new headers from infile headers
BITMAPFILEHEADER bf2 = bf;
BITMAPINFOHEADER bi2 = bi;
//edit new infile header's width and height
bi2.biHeight = bi.biHeight * n;
bi2.biWidth = bi.biWidth * n;
// determine padding for scanlines
int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
int padding2 = (4 - (bi2.biWidth * sizeof(RGBTRIPLE)) % 4) % 4;
//edit new infile header's size based off padding
bi2.biSizeImage = (bi2.biWidth * 3 + padding2) * abs(bi2.biHeight);
bf2.bfSize = bi2.biSizeImage + sizeof(BITMAPINFOHEADER) + sizeof(BITMAPFILEHEADER);
// write outfile's BITMAPFILEHEADER
fwrite(&bf2, sizeof(BITMAPFILEHEADER), 1, outptr);
// write outfile's BITMAPINFOHEADER
fwrite(&bi2, sizeof(BITMAPINFOHEADER), 1, outptr);
// iterate over infile's scanlines (vertically)
for (int i = 0, biHeight = abs(bi.biHeight); i < biHeight; i++)
{
for (int m = 0; m < n; m++) //loop to scale vertically
{
// iterate over pixels in infile's scanline (horizontally)
for (int j = 0; j < bi.biWidth; j++)
{
// temporary storage
RGBTRIPLE triple;
// read RGB triple from infile
fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
// write each horizontal RGB triple pixel to outfile n times
for (int k = 0; k < n; k++)
{
fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
}
}
// skip over padding in the infile, if any
fseek(inptr, padding, SEEK_CUR);
// write padding into outfile using fputc
for (int l = 0; l < padding2; l++)
{
fputc(0x00, outptr);
}
if (m < n-1) //cheated
{
// seek back to the beginning of the same row in the infile to scale vertically
fseek(inptr, -(long int)(bi.biWidth * sizeof(RGBTRIPLE) + padding) , SEEK_CUR);
}
}
}
// close infile
fclose(inptr);
// close outfile
fclose(outptr);
// that's all folks
return 0;
}