raf-timer/lib/index.js

An abstraction around requestionAnimationFrame.

'use strict';

var _createClass = function () { function defineProperties(target, props) { for (var i = 0; i < props.length; i++) { var descriptor = props[i]; descriptor.enumerable = descriptor.enumerable || false; descriptor.configurable = true; if ("value" in descriptor) descriptor.writable = true; Object.defineProperty(target, descriptor.key, descriptor); } } return function (Constructor, protoProps, staticProps) { if (protoProps) defineProperties(Constructor.prototype, protoProps); if (staticProps) defineProperties(Constructor, staticProps); return Constructor; }; }();

Object.defineProperty(exports, "__esModule", {
  value: true
});

var _performance = require('./performance.now()-polyfill');

var _performance2 = _interopRequireDefault(_performance);

var _requestAnimationFramePolyfill = require('./requestAnimationFrame-polyfill');

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

function _classCallCheck(instance, Constructor) { if (!(instance instanceof Constructor)) { throw new TypeError("Cannot call a class as a function"); } }

var numCallbacks = 0;
var callbackID = 0;
var animationFrameID = null;

var callbacks = {};
var runCallbacks = function runCallbacks(dt) {
  animationFrameID = null;
  for (var key in callbacks) {
    callbacks[key](dt);
    delete callbacks[key];
  }
};

var Timer = function () {
  function Timer() {
    var deltaTimeLimit = arguments.length <= 0 || arguments[0] === undefined ? 0.25 : arguments[0];

    _classCallCheck(this, Timer);

    this.microTime = (0, _performance2.default)();
    this.deltaTime = 0;
    this.deltaTimeLimit = deltaTimeLimit;
    this.animationFrameID = null;
  }

  _createClass(Timer, [{
    key: 'cancelFrame',
    value: function cancelFrame() {
      delete callbacks[this.animationFrameID];

      if (numCallbacks === 0) {
        (0, _requestAnimationFramePolyfill.cancelAnimationFrame)(animationFrameID);
        animationFrameID = null;
      }
    }
  }, {
    key: 'nextFrame',
    value: function nextFrame(callback) {
      var id = callbackID++;
      numCallbacks++;
      callbacks[id] = callback;
      this.animationFrameID = id;

      if (animationFrameID === null) {
        animationFrameID = (0, _requestAnimationFramePolyfill.requestAnimationFrame)(runCallbacks);
      }
    }
  }, {
    key: 'step',
    value: function step() {
      var dt = (0, _performance2.default)() - this.microTime;
      this.deltaTime = Math.max(0, Math.min(this.deltaTimeLimit, dt / 1000));
      return this.microTime += dt;
    }
  }, {
    key: 'delta',
    get: function get() {
      return this.deltaTime;
    }
  }, {
    key: 'fps',
    get: function get() {
      return this.deltaTime === 0 ? 0 : 1 / this.deltaTime;
    }
  }, {
    key: 'time',
    get: function get() {
      return this.microTime;
    }
  }]);

  return Timer;
}();

exports.default = Timer;