weex-nuke/src/node_modules/nuke-web-picker/lib/view/animate.js

基于 Rax 、Weex 的高性能组件体系 ~~

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.easeOutBounce = easeOutBounce;
exports.easeInOutQuad = easeInOutQuad;
var counter = 1;
var running = {};

var Animate = exports.Animate = {

  requestAnimationFrame: function () {
    // isomorphic support
    if (typeof window === 'undefined') {
      return function () {};
    }

    var requestFrame = window.requestAnimationFrame || window.webkitRequestAnimationFrame;

    return function (callback) {
      requestFrame(callback);
    };
  }(),

  start: function start(stepFunc, callback, duration, easeFunc) {
    var max = Math.max,
        min = Math.min;

    var animateId = counter++;

    var startTime = null,
        lastTime = null;

    running[animateId] = true;

    var step = function step(timeStamp) {
      if (running[animateId] !== true) {
        return;
      }

      if (startTime === null) {
        startTime = timeStamp;
        lastTime = timeStamp;
      }

      var percent = 0,
          timeDiff = timeStamp - startTime,
          timeFrame = timeStamp - lastTime;

      lastTime = timeStamp;

      if (duration) {
        percent = min(timeDiff / duration, 1);
      }

      if (percent >= 1 || running[animateId] !== true) {
        stepFunc(percent, timeDiff, timeFrame);
        callback();

        running[animateId] = false;
        delete running[animateId];
        return;
      }

      if (easeFunc) {
        percent = easeFunc(timeDiff, 0, 1, duration);
      }

      stepFunc(percent, timeDiff, timeFrame);

      Animate.requestAnimationFrame(step);
    };

    Animate.requestAnimationFrame(step);

    return animateId;
  },
  stop: function stop(animateId) {
    running[animateId] = false;
    delete running[animateId];
  }
};

function easeOutBounce(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;
  }
}

function easeInOutQuad(t, b, c, d) {
  if ((t /= d / 2) < 1) return c / 2 * t * t + b;
  return -c / 2 * (--t * (t - 2) - 1) + b;
}