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/**
* bmp.h
*
* Computer Science 50
* Problem Set 5
*
* BMP-related data types based on Microsoft's own.
*/
#include <stdint.h>
/**
* Common Data Types
*
* The data types in this section are essentially aliases for C/C++
* primitive data types.
*
* Adapted from http://msdn.microsoft.com/en-us/library/cc230309.aspx.
* See http://en.wikipedia.org/wiki/Stdint.h for more on stdint.h.
*/
typedef uint8_t BYTE;
typedef uint32_t DWORD;
typedef int32_t LONG;
typedef uint16_t WORD;
/**
* BITMAPFILEHEADER
*
* The BITMAPFILEHEADER structure contains information about the type, size,
* and layout of a file that contains a DIB [device-independent bitmap].
*
* Adapted from http://msdn.microsoft.com/en-us/library/dd183374(VS.85).aspx.
*/
typedef struct
{
WORD bfType;
DWORD bfSize;
WORD bfReserved1;
WORD bfReserved2;
DWORD bfOffBits;
} __attribute__((__packed__))
BITMAPFILEHEADER;
/**
* BITMAPINFOHEADER
*
* The BITMAPINFOHEADER structure contains information about the
* dimensions and color format of a DIB [device-independent bitmap].
*
* Adapted from http://msdn.microsoft.com/en-us/library/dd183376(VS.85).aspx.
*/
typedef struct
{
DWORD biSize;
LONG biWidth;
LONG biHeight;
WORD biPlanes;
WORD biBitCount;
DWORD biCompression;
DWORD biSizeImage;
LONG biXPelsPerMeter;
LONG biYPelsPerMeter;
DWORD biClrUsed;
DWORD biClrImportant;
} __attribute__((__packed__))
BITMAPINFOHEADER;
/**
* RGBTRIPLE
*
* This structure describes a color consisting of relative intensities of
* red, green, and blue.
*
* Adapted from http://msdn.microsoft.com/en-us/library/aa922590.aspx.
*/
typedef struct
{
BYTE rgbtBlue;
BYTE rgbtGreen;
BYTE rgbtRed;
} __attribute__((__packed__))
RGBTRIPLE;
#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;
}
//factor to resize by
const int FACTOR = atoi(argv[1]);
if (FACTOR < 1 || FACTOR > 100)
{
printf("Factor must be between 1 and 100\n");
return 2;
}
// remember filenames
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 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);
//specs of orginal image
int oldWidth = bi.biWidth;
int oldHeight = bi.biHeight;
int old_padding = ((4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4);
//resize image header
bi.biWidth *= FACTOR;
bi.biHeight *= FACTOR;
//buffer to store old scanline in
RGBTRIPLE scanline[oldWidth];
// determine padding for scanlines
int padding = ((4 - (bi.biWidth * sizeof(RGBTRIPLE)) % 4) % 4);
// size of new scanline
int sizeOfScanline = (bi.biWidth * sizeof(RGBTRIPLE)) + padding;
bi.biSizeImage = sizeOfScanline * (abs(bi.biHeight));
bf.bfSize = sizeof(BITMAPFILEHEADER) + sizeof(BITMAPINFOHEADER) + bi.biSizeImage;
// 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 5;
}
// 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, height = abs(oldHeight); i < height; i++)
{
// iterate over pixels in scanline
for (int j = 0; j < oldWidth; j++)
{
// read RGB triple from infile
fread(&scanline[j], sizeof(RGBTRIPLE), 1, inptr);
}
fseek(inptr, old_padding, SEEK_CUR);
//write FACTOR number of scanlines
for (int s = 0; s < FACTOR; s++)
{
//write a scanline
for (int l = 0; l < bi.biWidth; l++)
{
//write a pixel
for (int m = 0; m < FACTOR; m++)
{
// write RGB triple to outfile
fwrite(&scanline[l], sizeof(RGBTRIPLE), 1, outptr);
}
}
//add padding back
for (int n = 0; n < padding; n++)
{
fputc(0x00, outptr);
}
//reset file position indicator
fseek(outptr, -((sizeOfScanline - padding) * (FACTOR -1)), SEEK_CUR);
}
}
// close infile
fclose(inptr);
// close outfile
fclose(outptr);
return 0;
}
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