ticker.cpp

/*
ticker v0.1
-Karthik Karanth (c)2015
*/

/*
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

You should have received a copy of the GNU General Public License
along with this program.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <iostream>
#include <ncurses.h>
#include <cstring>
#include <unistd.h>
#include <sys/time.h>
#include <csignal>
#include <cstdlib>

///////////////////////////////////////
// data structures
///////////////////////////////////////
struct Timesig { //represents time signature in the form num / den
    int num, den;
};

///////////////////////////////////////
// function prototypes
///////////////////////////////////////
void displayHelp();
void resize(int sig);
float getWaitTime(float tempo, Timesig & timesig); //returns the interval between successive ticks
float getTempo(float waitTime, Timesig & timesig);
void drawFilledBox(int x, int y, int w, int h);
void drawEmptyBox(int x, int y, int w, int h);

///////////////////////////////////////
// global variables
///////////////////////////////////////
int width, height, startX, startY; //width/height of each tick's cell
float tempo = 80.0;
Timesig timesig = {4,4};

///////////////////////////////////////
// constants
///////////////////////////////////////
const int GAP = 2;

const int HIGHLIGHT_COLOR = 1;
const int NORMAL_COLOR = 2;
const int BORDER_COLOR = 3;

const float UPDATE_MS = 0.018; //Updates the terminal every UPDATE_MS milliseconds

int main(int argc, char** argv) {

    //parse command line arguments
    if(argc > 1) {
        int i = 1; //argv[0] is the executable's name
        while(i < argc) {
            if(strcmp(argv[i], "-h") == 0) {
                displayHelp();
                return 0;
            } else if(strcmp(argv[i], "-t") == 0) {
                i++;
                
                if(i>=argc) {
                    std::cerr << argv[0] << ": No tempo entered\n";
                    return 1;
                }
                
                char *err;
                tempo = strtof(argv[i], &err);
                if(strlen(err)) {
                    std::cerr << argv[0] << ": Invalid tempo: " << argv[i] << std::endl;
                    return 1;
                }
            } else if(strcmp(argv[i], "-s") == 0) {
                i++;
                if(i>=argc) {
                    std::cerr << argv[0] << ": Invalid time signature: " << argv[i] << std::endl;
                    return 2;
                }
                
                char *err;
                timesig.num = (int) strtol(argv[i], &err, 10);
                if(strlen(err)) {
                    std::cerr << argv[0] << ": Invalid time signature: " << argv[i] << std::endl;
                    return 2;
                }
                
                i++;
                if(i>=argc) {
                    std::cerr << argv[0] << ": Invalid time signature: " << argv[i] << std::endl;
                    return 2;
                }
                
                timesig.den = (int) strtol(argv[i], &err, 10);
                if(strlen(err)) {
                    std::cerr << argv[0] << ": Invalid time signature: " << argv[i] << std::endl;
                    return 2;
                }
            } else {
                std::cerr << argv[0] << ": Unrecognized option: " << argv[i] << std::endl;
                return 3;
            }
            
            i++;
        }
    }
    
    //initialize curses
    initscr();
    noecho();
    curs_set(0); //hide the cursor
    nodelay(stdscr, true);
    
    start_color();
    init_pair(HIGHLIGHT_COLOR, COLOR_WHITE, COLOR_GREEN);
    init_pair(NORMAL_COLOR, COLOR_WHITE, COLOR_RED);
    init_pair(BORDER_COLOR, COLOR_BLACK, COLOR_WHITE);
    
    float waitTime = getWaitTime(tempo, timesig);
    
    timeval tv;
    gettimeofday(&tv, NULL); //NULL represents the time zone, it defaults to the locale's default
    double initUpdateTime = tv.tv_sec + (tv.tv_usec / 1000000.0);
    double nextUpdateTime = waitTime;
    double currentUpdateTime;
    
    //resize sets the width and height
    resize(0);
    
    int attr;
    int tickPosition = 1;
    int x = startX + (tickPosition-1) * (GAP+width);
    
    //tell curses to call resize whenever the window is resized
    signal(SIGWINCH, resize);
    
    bool paused = false;
    
    //used to setup the "tap tempo" feature
    float lastSpacePress = 0;
    
    while(true) {
        // input
        char c = getch();
        switch(c) {
            //quit
            case 'q':
                endwin();
                return 0;
            
            //increase tempo
            case '+':
            case '=':
                tempo += 1;
                waitTime = getWaitTime(tempo, timesig);
                tickPosition = 1;
                nextUpdateTime = currentUpdateTime + waitTime;
                break;
            //decrease tempo
            case '-':
                tempo -= 1;
                waitTime = getWaitTime(tempo, timesig);
                tickPosition = 1;
                nextUpdateTime = currentUpdateTime + waitTime;
                break;
                
            //tap tempo
            case ' ':
                waitTime = currentUpdateTime - lastSpacePress;
                tempo = getTempo(waitTime, timesig);
                lastSpacePress = currentUpdateTime;
                nextUpdateTime = currentUpdateTime + waitTime;
                tickPosition = 1;               
                break;
            
            case 'p':
                if(paused) {                    
                    paused = false;
                } else {
                    paused = true;
                }
                break;
        }
    
        // update
        if(!paused) {
            gettimeofday(&tv, NULL);
            currentUpdateTime = tv.tv_sec + (tv.tv_usec / 1000000.0) - initUpdateTime;
        
            if(currentUpdateTime >= nextUpdateTime) {           
                tickPosition++;
                if(tickPosition > timesig.num) {
                    tickPosition = 1;
                }                       
                nextUpdateTime = currentUpdateTime + waitTime;
            }
        }

        // draw
        clear();
        
        if(tickPosition == 1) {
            attr = COLOR_PAIR(HIGHLIGHT_COLOR) | A_BOLD;
        } else {
            attr = COLOR_PAIR(NORMAL_COLOR);
        }
        x = startX + (tickPosition-1) * (GAP+width);
        attron(COLOR_PAIR(BORDER_COLOR));
        drawEmptyBox(x, startY, width, height);     
        attroff(COLOR_PAIR(BORDER_COLOR));
        
        attron(attr);       
        drawFilledBox(x+1, startY+1, width-2, height-2);    
        attroff(attr);
        
        mvprintw(LINES-1, COLS-45, "%1.1f bpm, %d/%d signature, %1.2fs elapsed", tempo, timesig.num, timesig.den, currentUpdateTime);
        
        refresh();
        
        // sleep
        usleep(UPDATE_MS * 1000000);
    }

    return 0;
}

void displayHelp() {
    using namespace std;
    cout 
        << "Usage: ticker [options]" << endl
        << "Options:\n"
        << "  -h          show this help message\n"
        << "  -t <tempo>  set the tempo\n"
        << "  -s <a> <b>  set the time signature to a/b" << endl;
}

void resize(int sig) {
    endwin();
    refresh();
    clear();
    
    width = (COLS - (GAP * (timesig.num+1))) / timesig.num;
    height = LINES - (GAP*3);
    startX = GAP;
    startY = GAP;
}

float getWaitTime(float tempo, Timesig & timesig) {
    //assumes bpm corresponds to quarter notes
    //return (60.0/tempo) * (4.0 / timesig.den);
    return 240.0/(tempo*timesig.den);
}

float getTempo(float waitTime, Timesig & timesig) {
    return 240.0/(waitTime*timesig.den);
}

void drawFilledBox(int x, int y, int w, int h) {
    for(int j = y; j<=(y+h); j++) {
        mvhline(j,x,' ',w+1);
    }
}

void drawEmptyBox(int x, int y, int w, int h) {
    mvvline(y, x, ' ', h);
    mvvline(y, x+w, ' ', h);
    mvhline(y,x, ' ', w);
    mvhline(y+h,x, ' ', w+1); //don't know why +1 is required
}