tweenjs缓动算法的使用实例分析

本文实例讲述了tweenjs缓动算法的使用。分享给大家供大家参考，具体如下：

这里的tweenjs不是依托于createjs的tewwnjs，而是一系列缓动算法集合。因为本身是算法，可以用在各个业务场景中，这也正是总结学习它的价值所在。tweenjs代码详情：

/* * Tween.js * t: current time（当前时间）； * b: beginning value（初始值）； * c: change in value（变化量）； * d: duration（持续时间）。 * you can visit 'http://easings.net/zh-cn' to get effect*/var Tween = {  Linear: function(t, b, c, d) {    return c * t / d + b;  },  Quad: {    easeIn: function(t, b, c, d) {      return c * (t /= d) * t + b;    },    easeOut: function(t, b, c, d) {      return -c *(t /= d)*(t-2) + b;    },    easeInOut: function(t, b, c, d) {      if ((t /= d / 2) < 1) return c / 2 * t * t + b;      return -c / 2 * ((--t) * (t-2) - 1) + b;    }  },  Cubic: {    easeIn: function(t, b, c, d) {      return c * (t /= d) * t * t + b;    },    easeOut: function(t, b, c, d) {      return c * ((t = t/d - 1) * t * t + 1) + b;    },    easeInOut: function(t, b, c, d) {      if ((t /= d / 2) < 1) return c / 2 * t * t*t + b;      return c / 2*((t -= 2) * t * t + 2) + b;    }  },  Quart: {    easeIn: function(t, b, c, d) {      return c * (t /= d) * t * t*t + b;    },    easeOut: function(t, b, c, d) {      return -c * ((t = t/d - 1) * t * t*t - 1) + b;    },    easeInOut: function(t, b, c, d) {      if ((t /= d / 2) < 1) return c / 2 * t * t * t * t + b;      return -c / 2 * ((t -= 2) * t * t*t - 2) + b;    }  },  Quint: {    easeIn: function(t, b, c, d) {      return c * (t /= d) * t * t * t * t + b;    },    easeOut: function(t, b, c, d) {      return c * ((t = t/d - 1) * t * t * t * t + 1) + b;    },    easeInOut: function(t, b, c, d) {      if ((t /= d / 2) < 1) return c / 2 * t * t * t * t * t + b;      return c / 2*((t -= 2) * t * t * t * t + 2) + b;    }  },  Sine: {    easeIn: function(t, b, c, d) {      return -c * Math.cos(t/d * (Math.PI/2)) + c + b;    },    easeOut: function(t, b, c, d) {      return c * Math.sin(t/d * (Math.PI/2)) + b;    },    easeInOut: function(t, b, c, d) {      return -c / 2 * (Math.cos(Math.PI * t/d) - 1) + b;    }  },  Expo: {    easeIn: function(t, b, c, d) {      return (t==0) ? b : c * Math.pow(2, 10 * (t/d - 1)) + b;    },    easeOut: function(t, b, c, d) {      return (t==d) ? b + c : c * (-Math.pow(2, -10 * t/d) + 1) + b;    },    easeInOut: function(t, b, c, d) {      if (t==0) return b;      if (t==d) return b+c;      if ((t /= d / 2) < 1) return c / 2 * Math.pow(2, 10 * (t - 1)) + b;      return c / 2 * (-Math.pow(2, -10 * --t) + 2) + b;    }  },  Circ: {    easeIn: function(t, b, c, d) {      return -c * (Math.sqrt(1 - (t /= d) * t) - 1) + b;    },    easeOut: function(t, b, c, d) {      return c * Math.sqrt(1 - (t = t/d - 1) * t) + b;    },    easeInOut: function(t, b, c, d) {      if ((t /= d / 2) < 1) return -c / 2 * (Math.sqrt(1 - t * t) - 1) + b;      return c / 2 * (Math.sqrt(1 - (t -= 2) * t) + 1) + b;    }  },  Elastic: {    easeIn: function(t, b, c, d, a, p) {      var s;      if (t==0) return b;      if ((t /= d) == 1) return b + c;      if (typeof p == "undefined") p = d * .3;      if (!a || a < Math.abs(c)) {        s = p / 4;        a = c;      } else {        s = p / (2 * Math.PI) * Math.asin(c / a);      }      return -(a * Math.pow(2, 10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;    },    easeOut: function(t, b, c, d, a, p) {      var s;      if (t==0) return b;      if ((t /= d) == 1) return b + c;      if (typeof p == "undefined") p = d * .3;      if (!a || a < Math.abs(c)) {        a = c;        s = p / 4;      } else {        s = p/(2*Math.PI) * Math.asin(c/a);      }      return (a * Math.pow(2, -10 * t) * Math.sin((t * d - s) * (2 * Math.PI) / p) + c + b);    },    easeInOut: function(t, b, c, d, a, p) {      var s;      if (t==0) return b;      if ((t /= d / 2) == 2) return b+c;      if (typeof p == "undefined") p = d * (.3 * 1.5);      if (!a || a < Math.abs(c)) {        a = c;        s = p / 4;      } else {        s = p / (2 *Math.PI) * Math.asin(c / a);      }      if (t < 1) return -.5 * (a * Math.pow(2, 10* (t -=1 )) * Math.sin((t * d - s) * (2 * Math.PI) / p)) + b;      return a * Math.pow(2, -10 * (t -= 1)) * Math.sin((t * d - s) * (2 * Math.PI) / p ) * .5 + c + b;    }  },  Back: {    easeIn: function(t, b, c, d, s) {      if (typeof s == "undefined") s = 1.70158;      return c * (t /= d) * t * ((s + 1) * t - s) + b;    },    easeOut: function(t, b, c, d, s) {      if (typeof s == "undefined") s = 1.70158;      return c * ((t = t/d - 1) * t * ((s + 1) * t + s) + 1) + b;    },    easeInOut: function(t, b, c, d, s) {      if (typeof s == "undefined") s = 1.70158;      if ((t /= d / 2) < 1) return c / 2 * (t * t * (((s *= (1.525)) + 1) * t - s)) + b;      return c / 2*((t -= 2) * t * (((s *= (1.525)) + 1) * t + s) + 2) + b;    }  },  Bounce: {    easeIn: function(t, b, c, d) {      return c - Tween.Bounce.easeOut(d-t, 0, c, d) + b;    },    easeOut: function(t, b, c, d) {      if ((t /= d) < (1 / 2.75)) {        return c * (7.5625 * t * t) + b;      } else if (t < (2 / 2.75)) {        return c * (7.5625 * (t -= (1.5 / 2.75)) * t + .75) + b;      } else if (t < (2.5 / 2.75)) {        return c * (7.5625 * (t -= (2.25 / 2.75)) * t + .9375) + b;      } else {        return c * (7.5625 * (t -= (2.625 / 2.75)) * t + .984375) + b;      }    },    easeInOut: function(t, b, c, d) {      if (t < d / 2) {        return Tween.Bounce.easeIn(t * 2, 0, c, d) * .5 + b;      } else {        return Tween.Bounce.easeOut(t * 2 - d, 0, c, d) * .5 + c * .5 + b;      }    }  }}Math.tween = Tween;