pngwatermark.cpp

//sudo apt-get install libpng++-dev
//g++ watermark.cpp -lpng
#include "png++/png.hpp"
#include <iostream>
#include <fstream>
#include <ctime>

using std::cout;
using std::endl;
using std::ifstream;


const int PIX_WID=5;
const int PIX_HEI=4;

int px_font_lookup[17][PIX_WID][PIX_HEI] =
{
    {   { 0, 1, 1, 0}, //0
        { 1, 0, 0, 1},
        { 1, 0, 0, 1},
        { 1, 0, 0, 1},
        { 0, 1, 1, 0} },
    {   { 0, 1, 0, 0}, //1
        { 1, 1, 0, 0},
        { 0, 1, 0, 0},
        { 0, 1, 0, 0},
        { 1, 1, 1, 0} },
    {   { 1, 1, 1, 0}, //2
        { 0, 0, 0, 1},
        { 0, 1, 1, 0},
        { 1, 0, 0, 0},
        { 1, 1, 1, 1} },
    {   { 1, 1, 1, 0}, //3
        { 0, 0, 0, 1},
        { 0, 1, 1, 0},
        { 0, 0, 0, 1},
        { 1, 1, 1, 0} },
    {   { 1, 0, 0, 1}, //4
        { 1, 0, 0, 1},
        { 1, 1, 1, 1},
        { 0, 0, 0, 1},
        { 0, 0, 0, 1} },
    {   { 1, 1, 1, 1}, //5
        { 1, 0, 0, 0},
        { 1, 1, 1, 0},
        { 0, 0, 0, 1},
        { 1, 1, 1, 0} },
    {   { 0, 1, 1, 0}, //6
        { 1, 0, 0, 0},
        { 1, 1, 1, 0},
        { 1, 0, 0, 1},
        { 0, 1, 1, 0} },
    {   { 1, 1, 1, 1}, //7
        { 0, 0, 0, 1},
        { 0, 0, 1, 0},
        { 0, 1, 0, 0},
        { 0, 1, 0, 0} },
    {   { 0, 1, 1, 0}, //8
        { 1, 0, 0, 1},
        { 0, 1, 1, 0},
        { 1, 0, 0, 1},
        { 0, 1, 1, 0} },
    {   { 0, 1, 1, 0}, //9
        { 1, 0, 0, 1},
        { 0, 1, 1, 1},
        { 0, 0, 0, 1},
        { 0, 1, 1, 0} },
    {   { 0, 0, 0, 1}, // [slash] /
        { 0, 0, 1, 0},
        { 0, 1, 1, 0},
        { 0, 1, 0, 0},
        { 1, 0, 0, 0} },
    {   { 0, 0, 0, 0}, // :
        { 0, 1, 1, 0},
        { 0, 0, 0, 0},
        { 0, 1, 1, 0},
        { 0, 0, 0, 0} },
    {   { 0, 0, 0, 0}, // [space]
        { 0, 0, 0, 0},
        { 0, 0, 0, 0},
        { 0, 0, 0, 0},
        { 0, 0, 0, 0} },
    {   { 0, 1, 1, 0}, //'a' [13]
        { 1, 0, 0, 1},
        { 1, 1, 1, 1},
        { 1, 0, 0, 1},
        { 1, 0, 0, 1} },
    {   { 1, 1, 1, 0}, //'p' [14]
        { 1, 0, 0, 1},
        { 1, 1, 1, 0},
        { 1, 0, 0, 0},
        { 1, 0, 0, 0} },
    {   { 1, 0, 0, 1}, //'m' [15]
        { 1, 1, 1, 1},
        { 1, 0, 0, 1},
        { 1, 0, 0, 1},
        { 1, 0, 0, 1} },
    {   { 1, 0, 0, 0}, //'|' [16]
        { 1, 0, 0, 0},
        { 1, 0, 0, 0},
        { 1, 0, 0, 0},
        { 1, 0, 0, 0} }
};

int write_pixel(png::image< png::rgb_pixel >& img, int x, int y, png::rgb_pixel pixel)
{
    if (0<=y && y<img.get_height() && 0<=x && x<img.get_width()) { img[y][x] = pixel; }
}

int write_index(png::image< png::rgb_pixel >& img, int x, int y, int index)
{
    for(int i=0; i<4; i++)
    {
        for(int j=0; j<5; j++)
        {
            //int v = px_font_lookup[ index ][j][i];
            //int vv = (1-v)*255;//[0,1] maps to [0,255]
            //cout << j <<":" << i <<
            //write_pixel(img, x+i, y+j, png::rgb_pixel(vv, vv, vv)
            if (px_font_lookup[ index ][j][i])
            {
                write_pixel(img, x+i, y+j, png::rgb_pixel(0, 0, 0));
            }
        }
    }
}

int write_digit(png::image< png::rgb_pixel >& img, int x, int y, int d){ if (0<=d && d<=9){ write_index(img, x, y, d); } }
int write_slash(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 10); }
int write_colon(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 11); }
int write_space(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 12); }
int write_a_upp(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 13); }
int write_p_upp(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 14); }
int write_m_upp(png::image< png::rgb_pixel >& img, int x, int y) { write_index(img, x, y, 15); }

int write_date(png::image< png::rgb_pixel >& img, int x, int y, time_t t)
{
    int z=0;//cursor
    struct tm * lt = localtime(&t);

    int mm = lt->tm_mon+1; int dd = lt->tm_mday; int yyyy = lt->tm_year+1900;
    write_digit(img, x+(z++*5), y, (mm%100)/10);
    write_digit(img, x+(z++*5), y, (mm%10)/1);
    write_slash(img, x+(z++*5), y);
    write_digit(img, x+(z++*5), y, (dd%100)/10);
    write_digit(img, x+(z++*5), y, (dd%10)/1);
    write_slash(img, x+(z++*5), y);
    write_digit(img, x+(z++*5), y, (yyyy%10000)/1000);
    write_digit(img, x+(z++*5), y, (yyyy%1000)/100);
    write_digit(img, x+(z++*5), y, (yyyy%100)/10);
    write_digit(img, x+(z++*5), y, (yyyy%10)/1);
    write_space(img, x+(z++*5), y);

    int hh = lt->tm_hour%12; int ii = lt->tm_min; int ss = lt->tm_sec; int am = lt->tm_hour<=12;
    write_digit(img, x+(z++*5), y, (hh%100)/10);
    write_digit(img, x+(z++*5), y, (hh%10)/1);
    write_colon(img, x+(z++*5), y);
    write_digit(img, x+(z++*5), y, (ii%100)/10);
    write_digit(img, x+(z++*5), y, (ii%10)/1);
    write_colon(img, x+(z++*5), y);
    write_digit(img, x+(z++*5), y, (ss%100)/10);
    write_digit(img, x+(z++*5), y, (ss%10)/1);
    write_space(img, x+(z++*5), y);
    if (am) { write_a_upp(img, x+(z++*5), y); }
    else    { write_p_upp(img, x+(z++*5), y); }
    write_m_upp(img, x+(z++*5), y);
}

bool file_exists(const char *filename) { ifstream ifile(filename); return ifile.good(); }


int main(int argc, char **argv)
{
    char empty[]="";
    char* input_file = empty;
    char* water_file = empty;
    char* output_file = empty;

    if (argc!=7)
    {
        cout << "Usage:" << endl;
        cout << "" << argv[0] << " -i input.png -w watermark.png -o output.png" <<endl;
        exit(0);
    }
    for(int i=1; i<6; i++)
    {
        if      (strcmp(argv[i],"-i")==0) { input_file = argv[++i]; }
        else if (strcmp(argv[i],"-w")==0) { water_file = argv[++i]; }
        else if (strcmp(argv[i],"-o")==0) { output_file = argv[++i]; }
    }
    if (!file_exists(input_file )) { cout << "Error: file "<< input_file  << " does not exist."<<endl; exit(0); }
    if (!file_exists(water_file )) { cout << "Error: file "<< water_file  << " does not exist."<<endl; exit(0); }
    //if (file_exists(output_file)) { cout << "Error: file "<< output_file << " exists."<<endl; exit(0); }

    //overlay watermark, centered
    int start,mwidth,mheight;
    png::image< png::rgb_pixel > img( input_file );

    png::image< png::rgb_pixel > wmark( water_file );
    start = (img.get_width()/2) - (wmark.get_width()/2);
    start = start<0 ? 0 : start;
    mwidth = (start+wmark.get_width()) > img.get_width() ? img.get_width() : (start+wmark.get_width());
    mheight = wmark.get_height() > img.get_height() ? img.get_height() : wmark.get_height();
    for(int i=start; i<mwidth; i++)
    {
        for(int j=0; j<mheight; j++)
        {
            img[j][i] = wmark[j][i-start];
        }
    }

    //write date on watermark
    time_t rawtime = time(NULL);
    write_date(img, start+136, (wmark.get_height()-5)/2, rawtime);

    img.write( output_file );

    return 0;
}