timing-function/lib/timingFunction.js

Simple API for easing functions and Bezier curves

// Generated by CoffeeScript 1.8.0
var UnitBezier, isFinite, timingFunction;

UnitBezier = require('./UnitBezier');

module.exports = timingFunction = {
  UnitBezier: UnitBezier,
  linear: function(p) {
    return p;
  },
  define: function(name, func) {
    var _func, _name;
    if (typeof name === 'object') {
      for (_name in name) {
        _func = name[_name];
        timingFunction.define(_name, _func);
      }
      return;
    }
    return timingFunction[name] = {
      easeIn: func,
      easeOut: function(p, x) {
        return 1 - func(1 - p, x);
      },
      easeInOut: function(p, x) {
        if (p <= 0.5) {
          return 0.5 * func(p * 2, x);
        } else {
          return 0.5 * (2 - func(2 * (1 - p), x));
        }
      }
    };
  },
  get: function(func, x) {
    var b, comp, f, i, part, parts, _i, _j, _len, _len1;
    if (func instanceof Function) {
      return func;
    } else if ((arguments[1] != null) && (arguments[2] != null) && (arguments[3] != null)) {
      b = new UnitBezier(arguments[0], arguments[1], arguments[2], arguments[3]);
      return function(p) {
        return b.solveSimple(p);
      };
    }
    if (Array.isArray(func)) {
      return timingFunction.get.apply(null, func);
    }
    if (typeof func !== 'string') {
      throw Error("func should either be a function or a string, like 'cubic.easeOut'");
    }
    if (func.match(/\,/)) {
      parts = func.split(/\,/);
      if (parts.length !== 4) {
        throw Error("Invalid func '" + func + "'");
      }
      for (i = _i = 0, _len = parts.length; _i < _len; i = ++_i) {
        part = parts[i];
        comp = parseFloat(part.replace(/\s+/g, ''));
        if (!isFinite(comp)) {
          throw Error("Invalid number '" + part + "' in '" + func + "'");
        }
        parts[i] = comp;
      }
      b = new UnitBezier(parts[0], parts[1], parts[2], parts[3]);
      return function(p) {
        return b.solveSimple(p);
      };
    }
    parts = func.split('.');
    f = timingFunction;
    for (_j = 0, _len1 = parts.length; _j < _len1; _j++) {
      part = parts[_j];
      f = f[part];
    }
    if (typeof f === 'undefined') {
      throw Error("Cannot find easing function '" + func + "'");
    }
    if (x != null) {
      return function(p) {
        return f(p, x);
      };
    }
    return f;
  }
};

timingFunction.define({
  quad: function(p) {
    return Math.pow(p, 2);
  },
  cubic: function(p) {
    return Math.pow(p, 3);
  },
  quart: function(p) {
    return Math.pow(p, 4);
  },
  quint: function(p) {
    return Math.pow(p, 5);
  },
  expo: function(p) {
    return Math.pow(2, 8 * (p - 1));
  },
  circ: function(p) {
    return 1 - Math.sin(Math.cos(p));
  },
  sine: function(p) {
    return 1 - Math.cos(p * Math.PI / 2);
  },
  elastic: function(p, x) {
    return Math.pow(2, 10 * (p - 1)) * Math.cos(20 * Math.PI * x / 3 * p);
  },
  bow: function(p, x) {
    return Math.pow(p, 2) * ((x + 1) * p - x);
  },
  bounce: function(p) {
    for(var a = 0, b = 1, result; 1; a += b, b /= 2) {

			if (p >= (7 - 4 * a) / 11) {

				return -Math.pow((11 - 6 * a - 11 * p) / 4, 2) + Math.pow(b, 2)
			}

		}//;
  }
});

isFinite = function(value) {
  if (typeof value !== 'number') {
    return false;
  }
  if (value !== value || value === Infinity || value === -Infinity) {
    return false;
  }
  return true;
};