lottie-web/player/js/utils/expressions/expressionHelpers.js

After Effects plugin for exporting animations to SVG + JavaScript or canvas + JavaScript

import {
  createTypedArray,
} from '../helpers/arrays';
import ExpressionManager from './ExpressionManager';

const expressionHelpers = (function () {
  function searchExpressions(elem, data, prop) {
    if (data.x) {
      prop.k = true;
      prop.x = true;
      prop.initiateExpression = ExpressionManager.initiateExpression;
      prop.effectsSequence.push(prop.initiateExpression(elem, data, prop).bind(prop));
    }
  }

  function getValueAtTime(frameNum) {
    frameNum *= this.elem.globalData.frameRate;
    frameNum -= this.offsetTime;
    if (frameNum !== this._cachingAtTime.lastFrame) {
      this._cachingAtTime.lastIndex = this._cachingAtTime.lastFrame < frameNum ? this._cachingAtTime.lastIndex : 0;
      this._cachingAtTime.value = this.interpolateValue(frameNum, this._cachingAtTime);
      this._cachingAtTime.lastFrame = frameNum;
    }
    return this._cachingAtTime.value;
  }

  function getSpeedAtTime(frameNum) {
    var delta = -0.01;
    var v1 = this.getValueAtTime(frameNum);
    var v2 = this.getValueAtTime(frameNum + delta);
    var speed = 0;
    if (v1.length) {
      var i;
      for (i = 0; i < v1.length; i += 1) {
        speed += Math.pow(v2[i] - v1[i], 2);
      }
      speed = Math.sqrt(speed) * 100;
    } else {
      speed = 0;
    }
    return speed;
  }

  function getVelocityAtTime(frameNum) {
    if (this.vel !== undefined) {
      return this.vel;
    }
    var delta = -0.001;
    // frameNum += this.elem.data.st;
    var v1 = this.getValueAtTime(frameNum);
    var v2 = this.getValueAtTime(frameNum + delta);
    var velocity;
    if (v1.length) {
      velocity = createTypedArray('float32', v1.length);
      var i;
      for (i = 0; i < v1.length; i += 1) {
        // removing frameRate
        // if needed, don't add it here
        // velocity[i] = this.elem.globalData.frameRate*((v2[i] - v1[i])/delta);
        velocity[i] = (v2[i] - v1[i]) / delta;
      }
    } else {
      velocity = (v2 - v1) / delta;
    }
    return velocity;
  }

  function getStaticValueAtTime() {
    return this.pv;
  }

  function setGroupProperty(propertyGroup) {
    this.propertyGroup = propertyGroup;
  }

  return {
    searchExpressions: searchExpressions,
    getSpeedAtTime: getSpeedAtTime,
    getVelocityAtTime: getVelocityAtTime,
    getValueAtTime: getValueAtTime,
    getStaticValueAtTime: getStaticValueAtTime,
    setGroupProperty: setGroupProperty,
  };
}());

export default expressionHelpers;