animated/src/AnimatedModulo.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 Animated = require('./Animated');
var AnimatedWithChildren = require('./AnimatedWithChildren');
var AnimatedInterpolation = require('./AnimatedInterpolation');
var Interpolation = require('./Interpolation');

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

class AnimatedModulo extends AnimatedWithChildren {
  _a: Animated;
  _modulus: number; // TODO(lmr): Make modulus able to be an animated value
  _aListener: number;
  _listeners: {[key: number]: ValueListenerCallback};

  constructor(a: Animated, modulus: number) {
    super();
    this._a = a;
    this._modulus = modulus;
    this._listeners = {};
  }

  __getValue(): number {
    return (this._a.__getValue() % this._modulus + this._modulus) % this._modulus;
  }

  addListener(callback: ValueListenerCallback): string {
    if (!this._aListener) {
      this._aListener = this._a.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);
  }

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

module.exports = AnimatedModulo;