Canvas Drawing

Draw.js

var fs = require('fs');
var es = require('event-stream');

const { createCanvas } = require('canvas');
const canvas = createCanvas(1000, 1000);
const ctx = canvas.getContext('2d');

Number.prototype.clamp = function(min, max) {
  return Math.min(Math.max(this, min), max);
};

ctx.fillStyle = "white";
ctx.fillRect(0, 0, 1000, 1000);

pts = [];

var s = fs.createReadStream('/mnt/d/E.txt')
    .pipe(es.split('\n'))
    .pipe(es.mapSync(function(line){

        // pause the readstream
        s.pause();

        // process line here and call s.resume() when rdy
        // function below was for logging memory usage
        //logMemoryUsage(lineNr);

        var splited = line.split(', ');
        var x = 250+(10*parseFloat(splited[0].replace("(", ""))).clamp(-250, 750);
        var y = 900-(10*parseFloat(splited[1])).clamp(-100, 900);

        pts.push({X: x, Y:y});
        // resume the readstream, possibly from a callback
        s.resume();
    })
    .on('error', function(err){
        console.log('Error while reading file.', err);
    })
    .on('end', function(){
        console.log('Read entire file.');
        console.log("drawing");


        pts.forEach(element => {
          ctx.beginPath();
          ctx.fillStyle = "rgba(0, 0, 0, 0.01)";
          ctx.arc(element.X, element.Y, 0.75, 0, Math.PI * 2, true);
          ctx.fill();
          ctx.closePath();
        
          // console.log("draw", element);
        });
        
        var buf = canvas.toBuffer();
        fs.writeFileSync("D.png", buf);


        console.log("Done");
    })
);