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encode.cpp
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encode.cpp
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#include <string>
#include <stdio.h>
#include <stdlib.h>
#include "EasyBMP/EasyBMP.cpp"
using namespace std;
int main(int argc, char** argv) {
if (argc < 4) {
cout << "Not enough arguments." << endl;
return 1;
}
string message(argv[3]);
message = message + (char)10;
int len = message.length();
// Use EasyBMP to get all file stats
// It's just easier this way.
BMP sheldon;
sheldon.ReadFromFile(argv[1]);
int offset = sheldon.TellOffset();
int height = sheldon.TellHeight();
int width = sheldon.TellWidth();
cout << "Pixels start at: " << offset << endl;
cout << "Width of image: " << width << endl;
cout << "Height of image: " << height << endl;
// Open the BMP file for manipulation
FILE * input_file = fopen(argv[1], "rb");
long size;
size_t result;
unsigned char* memblock;
// Only proceed if we have a file
if (input_file != NULL) {
// get file size
fseek(input_file, 0, SEEK_END);
size = ftell(input_file);
rewind(input_file);
// Allocate memory for file read
// and read it into our memblock
// then close the file.
memblock = new unsigned char[size];
result = fread(memblock, sizeof(unsigned char), size, input_file);
fclose(input_file);
// only proceed if we have data.
if (result == size) {
// two vars, one for string position, the other for
// keeping track of pixel depth
int k = 0, depth = 0;
// iterate over all pixels
// i = memblock counter
// j = current char bit counter
// depth = pixel counter
for (int i = 0; i < size; i++) {
// only start manipulation if we are past the
// offset value.
if (i >= offset) {
// only add chars if we are in the bounds of
// our string
if (k < len) {
// get the character to manipulate
char curr = message[k];
// iterate over all it's bits
for (int j = 0; j < 8; j++) {
// if we are at the fourth byte, skip it
if (depth == 3) {
// decrement our bit counter
// reset the depth
// increment our byte counter
depth = 0; i++; j--;
// else, proceed with adding a bit to the end of a pixel.
} else {
// get the LSB for the current position in the string
unsigned char temp = (curr >> j) & 1;
// add it to the end of the current memory block
memblock[i] = ((memblock[i] >> 1) << 1) | temp;
// increment the depth and memblock counter.
i++; depth++;
}
}
// afterwards we increment our string counter and
// rewind back once in the memblock counter.
k++; i--;
} else {
break;
}
}
}
} else {
cout << "Did not read from file" << endl;
return 1;
}
} else {
return 1;
}
// write to our output file
FILE* output_file = fopen(argv[2], "wb");
if (output_file != NULL) {
result = fwrite(memblock, sizeof(unsigned char), size, output_file);
if (result != size) {
cout << "Did not write to file" << endl;
fclose(output_file);
delete[] memblock;
return 1;
}
fclose(output_file);
} else {
cout << "Could not open output file" << endl;
delete[] memblock;
return 1;
}
// delete the memory block
delete[] memblock;
return 0;
}