Created
December 4, 2018 10:35
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// Resizes a BMP file | |
#include <stdio.h> | |
#include <stdlib.h> | |
#include "bmp.h" | |
int main(int argc, char *argv[]) | |
{ | |
// ensure proper usage | |
if (argc != 4) | |
{ | |
fprintf(stderr, "Usage: resize size(n) infile outfile\n"); | |
return 1; | |
} | |
//convert char to an int | |
unsigned int n = atoi(argv[1]); | |
//ensure int is less than or equal to 100 | |
if (n <= 0 || n > 100) | |
{ | |
fprintf(stderr, "Usage: size(n) must be positive integer less than or equal to 100\n"); | |
return 1; | |
} | |
// 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, bfo; | |
fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr); | |
// read infile's BITMAPINFOHEADER | |
BITMAPINFOHEADER bi, bio; | |
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; | |
} | |
// change outfile's headers | |
bio = bi; | |
bfo = bf; | |
bio.biWidth = bi.biWidth *= n; | |
bio.biHeight = bi.biHeight *= n; | |
int padding = (4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; | |
int padding_out = (4 - (bio.biWidth * sizeof(RGBTRIPLE)) % 4) % 4; | |
bio.biSizeImage = ((sizeof(RGBTRIPLE) * bio.biWidth) + padding) * abs(bio.biHeight); | |
bfo.bfSize = bio.biSizeImage + sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER); | |
// write outfile's headers | |
fwrite(&bfo, sizeof(BITMAPFILEHEADER), 1, outptr); | |
fwrite(&bio, sizeof(BITMAPINFOHEADER), 1, outptr); | |
//iterate over scanline | |
for (int scanline = 0, biHeight = abs(bi.biHeight); scanline < biHeight; scanline++) | |
{ | |
//iterate over pixels | |
for (int pixels = 0; pixels < bi.biWidth; pixels++) | |
{ | |
//repeat n times | |
for (int repeat = 0; repeat < n; repeat++) | |
{ | |
//temporary storage | |
RGBTRIPLE triple; | |
fread(&triple, sizeof(RGBTRIPLE), 1, inptr); | |
//write to outfield n times | |
for (int print = 0; print < n; print++) | |
{ | |
fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr); | |
} | |
//add padding | |
for(int print_padding = 0; print_padding < padding_out; print_padding++) | |
{ | |
fputc(0x00, outptr); | |
} | |
} | |
//skip padding | |
fseek(inptr, padding, SEEK_CUR); | |
} | |
//repeat for next row | |
fseek(inptr, -((bi.biWidth * sizeof(RGBTRIPLE)) + padding), SEEK_CUR); | |
} | |
// close infile | |
fclose(inptr); | |
// close outfile | |
fclose(outptr); | |
// success | |
return 0; | |
} |
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