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// Copies a BMP file | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include <cs50.h> | |
#include "bmp.h" | |
int main(int argc, char *argv[]) | |
{ | |
// ensure proper usage | |
if (argc != 4) | |
{ | |
fprintf(stderr, "./resize n infile outfile\n"); | |
return 1; | |
} | |
// remember filenames | |
char *infile = argv[2]; | |
char *outfile = argv[3]; | |
// store resize value | |
int n = atoi(argv[1]); | |
// 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; | |
} | |
// resize height and width per specified n | |
bi.biWidth *= n; | |
bi.biHeight *= n; | |
// determine padding for scanlines | |
int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; | |
// determine new sizes | |
bi.biSizeImage = ((bi.biWidth * sizeof(RGBTRIPLE)) + padding) * abs(bi.biHeight); | |
bf.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + bi.biSizeImage; | |
// 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(bi.biHeight); i < biHeight; i++) | |
{ | |
// 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 | |
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 < padding; k++) | |
{ | |
fputc(0x00, outptr); | |
} | |
} | |
// close infile | |
fclose(inptr); | |
// close outfile | |
fclose(outptr); | |
// success | |
return 0; | |
} |
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