animated/src/AnimatedMultiplication.js

Declarative Animations Library for React and React Native

/**
 * Copyright (c) 2015-present, Facebook, Inc.
 * All rights reserved.
 *
 * This source code is licensed under the BSD-style license found in the
 * LICENSE file in the root directory of this source tree. An additional grant
 * of patent rights can be found in the PATENTS file in the same directory.
 *
 * @flow
 */
'use strict';

var AnimatedWithChildren = require('./AnimatedWithChildren');
var Animated = require('./Animated');
var AnimatedValue = require('./AnimatedValue');
var AnimatedInterpolation = require('./AnimatedInterpolation');
var Interpolation = require('./Interpolation');

import type { InterpolationConfigType } from './Interpolation';

class AnimatedMultiplication extends AnimatedWithChildren {
  _a: Animated;
  _b: Animated;
  _aListener: number;
  _bListener: number;
  _listeners: {[key: number]: ValueListenerCallback};

  constructor(a: Animated | number, b: Animated | number) {
    super();
    this._a = typeof a === 'number' ? new AnimatedValue(a) : a;
    this._b = typeof b === 'number' ? new AnimatedValue(b) : b;
    this._listeners = {};
  }

  __getValue(): number {
    return this._a.__getValue() * this._b.__getValue();
  }

  addListener(callback: ValueListenerCallback): string {
    if (!this._aListener && this._a.addListener) {
      this._aListener = this._a.addListener(() => {
        for (var key in this._listeners) {
          this._listeners[key]({value: this.__getValue()});
        }
      })
    }
    if (!this._bListener && this._b.addListener) {
      this._bListener = this._b.addListener(() => {
        for (var key in this._listeners) {
          this._listeners[key]({value: this.__getValue()});
        }
      })
    }
    var id = guid();
    this._listeners[id] = callback;
    return id;
  }

  removeListener(id: string): void {
    delete this._listeners[id];
  }

  interpolate(config: InterpolationConfigType): AnimatedInterpolation {
    return new AnimatedInterpolation(this, Interpolation.create(config));
  }

  __attach(): void {
    this._a.__addChild(this);
    this._b.__addChild(this);
  }

  __detach(): void {
    this._a.__removeChild(this);
    this._b.__removeChild(this);
  }
}

module.exports = AnimatedMultiplication;