cdf/src/inc/utils.js

A library for creating oldschool demo-like animations with JavaScript

var utils = {

  TWO_PI : Math.PI * 2,
  DEG_TO_RAD : Math.PI/180,
  RAD_TO_DEG : 180 / Math.PI,
  PI_BY_TWO : Math.PI / 2,

  coordRotate: function (xyPair, angleInDegrees, pivot) {
    var cx = (pivot && pivot[0]) ? pivot[0] : 0;
    var cy = (pivot && pivot[1]) ? pivot[1] : 0;
    var sin = Math.sin(angleInDegrees * utils.DEG_TO_RAD);
    var cos = Math.cos(angleInDegrees * utils.DEG_TO_RAD);
    return [
      (sin * (xyPair[0] - cx)) + (cos * (xyPair[1] - cy)) + cx,
      (sin * (xyPair[1] - cy)) - (cos * (xyPair[0] - cx)) + cy
    ]
  },
  clamp: function(val, min,max){
    return val <= min ? min : val >= max ? max : val;
  },
  coordPair: function(pair, defaultValue){
    if(pair === undefined) return defaultValue || [0,0];
    if(typeof pair === 'number') return [pair,pair];
    return pair;
  },
  between: function(val, min, max){
    return val >= min && val <= max;
  },
  strokeFill: function(c, fillStyle, lineWidth, strokeStyle, closePath){
    if(closePath) c.ctx.closePath();
    if (lineWidth) c.ctx.lineWidth = lineWidth;
    if (fillStyle) c.ctx.fillStyle = fillStyle;
    if (strokeStyle) c.ctx.strokeStyle = strokeStyle;
    if (lineWidth && strokeStyle) c.ctx.stroke();
    if (fillStyle) c.ctx.fill();
    return c;
  },


  inherit: function(BaseClass, constructor, prototype){
    var ChildClass = function(){ constructor.apply(this, arguments); }; // BaseClass.apply(this, arguments);
    ChildClass.prototype = Object.create(BaseClass.prototype);
    for(var pmn in prototype) if(prototype.hasOwnProperty(pmn)) {
      ChildClass[pmn] = prototype[pmn];
    }
    return ChildClass;
  },

  eventer: function(obj){
    obj.on = function(event, handler, once){

      if(typeof handler !== "function")return;
      this.__eventHandlers = this.__eventHandlers || {};
      this.__eventHandlers[event] = this.__eventHandlers[event] || [];
      this.__eventHandlers[event].push({
        callback:handler,
        once: !!once
      });

      this.__lastAssignedEvent = event;
      return this;
    };

    obj.trigger = function(event, thisObj, args){
      if(event === undefined) event = this.__lastAssignedEvent;
      if(!this.__eventHandlers || typeof this.__eventHandlers[event] === "undefined" || !this.__eventHandlers[event].forEach) return this;
      thisObj = thisObj || this;
      args = args || [];
      for(var i =0; i<this.__eventHandlers[event].length; i++){
        var data = this.__eventHandlers[event][i];
        if(data && data.callback){
          data.callback.apply(thisObj, args);
          if(data.once){
            delete this.__eventHandlers[event][i];
          }
        }
      }
      return this;
    };
    return obj;
  },

  shorthands: function(){  require('inc/shorthands')(require('cdf')); }

};



var requestAnimFrameOriginal = window.requestAnimationFrame ||
  window.webkitRequestAnimationFrame ||
  window.mozRequestAnimationFrame ||
  window.oRequestAnimationFrame ||
  window.msRequestAnimationFrame;

utils.frame = requestAnimFrameOriginal ? function (callback) {
  requestAnimFrameOriginal.call(window, callback);
} : function (callback) {
  window.setTimeout(callback, 1000 / 60);
};

module.exports = utils;