Function getInitialState

index.js:69–115

()

  },

  getInitialState() {
    const containerWidth = Dimensions.get('window').width;
    let scrollValue;
    let scrollXIOS;
    let positionAndroid;
    let offsetAndroid;

    if (Platform.OS === 'ios') {
      scrollXIOS = new Animated.Value(this.props.initialPage * containerWidth);
      const containerWidthAnimatedValue = new Animated.Value(containerWidth);
      // Need to call __makeNative manually to avoid a native animated bug. See
      // https://github.com/facebook/react-native/pull/14435
      containerWidthAnimatedValue.__makeNative();
      scrollValue = Animated.divide(scrollXIOS, containerWidthAnimatedValue);

      const callListeners = this._polyfillAnimatedValue(scrollValue);
      scrollXIOS.addListener(
        ({ value, }) => callListeners(value / this.state.containerWidth)
      );
    } else {
      positionAndroid = new Animated.Value(this.props.initialPage);
      offsetAndroid = new Animated.Value(0);
      scrollValue = Animated.add(positionAndroid, offsetAndroid);

      const callListeners = this._polyfillAnimatedValue(scrollValue);
      let positionAndroidValue = this.props.initialPage;
      let offsetAndroidValue = 0;
      positionAndroid.addListener(({ value, }) => {
        positionAndroidValue = value;
        callListeners(positionAndroidValue + offsetAndroidValue);
      });
      offsetAndroid.addListener(({ value, }) => {
        offsetAndroidValue = value;
        callListeners(positionAndroidValue + offsetAndroidValue);
      });
    }

    return {
      currentPage: this.props.initialPage,
      scrollValue,
      scrollXIOS,
      positionAndroid,
      offsetAndroid,
      containerWidth,
      sceneKeys: this.newSceneKeys({ currentPage: this.props.initialPage, }),
    };
  },

  componentDidUpdate(prevProps) {
    if (this.props.children !== prevProps.children) {