135 lines
3.5 KiB
C
135 lines
3.5 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <math.h>
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#include <ctype.h>
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#include "bmp.h"
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int main(int argc, char *argv[])
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{
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// ensure proper usage
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if (argc != 4)
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{
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fprintf(stderr, "Usage: ./resize n infile outfile\n");
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return 1;
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}
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// remember resize factor n
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int n = atoi(argv[1]);
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// remember filenames
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char *infile = argv[2];
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char *outfile = argv[3];
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// open input file
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FILE *inptr = fopen(infile, "r");
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if (inptr == NULL)
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{
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fprintf(stderr, "Could not open %s.\n", infile);
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return 2;
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}
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// open output file
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FILE *outptr = fopen(outfile, "w");
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if (outptr == NULL)
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{
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fclose(inptr);
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fprintf(stderr, "Could not create %s.\n", outfile);
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return 3;
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}
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// read infile's BITMAPFILEHEADER
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BITMAPFILEHEADER bf;
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fread(&bf, sizeof(BITMAPFILEHEADER), 1, inptr);
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// read infile's BITMAPINFOHEADER
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BITMAPINFOHEADER bi;
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fread(&bi, sizeof(BITMAPINFOHEADER), 1, inptr);
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// ensure infile is (likely) a 24-bit uncompressed BMP 4.0
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if (bf.bfType != 0x4d42 || bf.bfOffBits != 54 || bi.biSize != 40 ||
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bi.biBitCount != 24 || bi.biCompression != 0)
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{
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fclose(outptr);
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fclose(inptr);
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fprintf(stderr, "Unsupported file format.\n");
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return 4;
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}
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// store all old header info which we will change
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int oldWidth = bi.biWidth;
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int oldPadding = (4 - (oldWidth * sizeof(RGBTRIPLE)) % 4) % 4;
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int oldHeight = bi.biHeight;
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int oldSizeImage = bi.biSizeImage;
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int oldSize = bf.bfSize;
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// calculate and store new header info
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int newWidth = bi.biWidth * n;
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int newPadding = (4 - (newWidth * sizeof(RGBTRIPLE)) % 4) % 4;
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int newHeight = bi.biHeight * n;
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int newSizeImage = ((((newWidth * bi.biBitCount) + 31) & ~31) / 8) * abs(newHeight);
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int newSize = 54 + newWidth * abs(newHeight) * 3 + abs(newHeight) * newPadding;
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// update header info
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bi.biWidth = newWidth;
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bi.biHeight = newHeight;
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bi.biSizeImage = newSizeImage;
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bf.bfSize = newSize;
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// write outfile's BITMAPFILEHEADER
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fwrite(&bf, sizeof(BITMAPFILEHEADER), 1, outptr);
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// write outfile's BITMAPINFOHEADER
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fwrite(&bi, sizeof(BITMAPINFOHEADER), 1, outptr);
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// Go through reading each scanline
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for (int i = 0; i < abs(oldHeight); i++)
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{
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// process of reading and writing the line n times
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for (int j = 0; j < n; j++)
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{
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// go through each pixel to copy and write n times
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for (int k = 0; k < oldWidth; k++)
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{
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// temporary triple
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RGBTRIPLE triple;
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fread(&triple, sizeof(RGBTRIPLE), 1, inptr);
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// Write the triple N times
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for (int l = 0; l < n; l++)
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{
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fwrite(&triple, sizeof(RGBTRIPLE), 1, outptr);
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}
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}
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// add newPadding
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for (int k = 0; k < newPadding; k++)
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{
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fputc(0x00, outptr);
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}
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// Check whether we are on last one, and if not reset the file pointer
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if (j < n - 1)
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{
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fseek(inptr, -oldWidth * sizeof(RGBTRIPLE), SEEK_CUR);
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}
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}
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// skip reading the old padding once we are done reading/writing and ready to
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// move to the next line
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fseek(inptr, oldPadding, SEEK_CUR);
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}
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// close infile
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fclose(inptr);
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// close outfile
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fclose(outptr);
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// success
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return 0;
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} |