reactjs - 反应原生动画值作为函数参数

Question

我是 React native 的新手，学习 Animation 发现了 Blow 代码，差不多一个星期试图了解如果它在构造函数中如何继续调用此函数，以及文档中描述的这种技术在哪里，请解释甚至更好地参考文档在哪里描述。

this._x = fixValue(this.pan)

完整代码：

import React, { Component } from "react";
import { Animated, View, StyleSheet, PanResponder, Text } from "react-native";

function fixValue( valueX ){

// some code here

return valueX;

}

export default class App extends Component {

constructor(props){
  super(props);

  this.pan = new Animated.Value(0);



  this.panResponder = PanResponder.create({
   onMoveShouldSetPanResponder: () => true,
    onPanResponderMove: Animated.event([
      null,
      { dx: this.pan }
    ], {useNativeDriver: false}),

  });

  this._x = fixValue(this.pan);
}

  render() {
    return (
      <View style={styles.container}>

        <Animated.View
          style={{
            transform: [{ translateX: this._x }]
          }}
          {...this.panResponder.panHandlers}
        >
          <View style={styles.box} />
        </Animated.View>

      </View>
    );
  }
}

const styles = StyleSheet.create({
  container: {
    flex: 1,
    alignItems: "center",
    justifyContent: "center"
  },

  box: {
    height: 100,
    width: 100,
    backgroundColor: "blue",
    borderRadius: 5
  }
});

https://snack.expo.io/gf97TEON4