SearchBarAnimation.js

constructor(initialState) {
  this.initialState = initialState;

  this._createClampedScroll();
  this.scrollY.addListener(this._updateScroll);
}

_updateScroll = ({value}) => {
  const diff = value - this._scrollValue;
  this._scrollValue = Math.max(value, this.topPartHeight); // Fix normal state
  this._clampedScrollValue = Math.min(
    Math.max(this._clampedScrollValue + diff, this.minClamp), 
    this.maxClamp
  );

  this._changeStatusBarStyle();
  this._changeStateBar();
};

_createClampedScroll() {
  this.clampedScroll = Animated.diffClamp(
    this.scrollY.interpolate({ // Only positive
      inputRange: [0, 1],
      outputRange: [0, 1],
      extrapolateLeft: 'clamp',
    }).interpolate({ // Fix normal state
      inputRange: [0, this.topPartHeight],
      outputRange: [this.topPartHeight, this.topPartHeight],
      extrapolate: 'identity',
    }), 
    this.minClamp,
    this.maxClamp,
  );
}

_changeStateBar() {
    let newState, types = this.stateBarTypes;
    let clampedValue = Math.round(this._clampedScrollValue);
    if(Math.round(this.scrollY._value) < this.topPartHeight) {
      newState = types.EXPANDED;
    } else if(clampedValue == this.minClamp) {
      newState = types.NORMAL;
    } else if(clampedValue == this.maxClamp) {
      newState = types.CLAMPED;
    }

    if(newState != undefined && newState != this.stateBar) {
      this.stateBar = newState;
    }
  }

_changeStatusBarStyle() {
  let statusBarStyle = Math.round(this._clampedScrollValue) != this.maxClamp ? 
                      'light-content' : 
                      'dark-content';

  if(statusBarStyle != this._statusBarStyle) {
    StatusBar.setBarStyle(statusBarStyle);
    this._statusBarStyle = statusBarStyle;
  }
}