HarmonyOS 鸿蒙Next 使用react-native-fresh-refresh做下拉刷新无效果

通过 FlatList 的 onScroll 事件来监听下拉动作，并在达到一定阈值时触发刷新，同时用 LottieView 替换掉系统的默认 RefreshControl

demo：

import React, { useState, useRef, useCallback } from 'react';
import { Text, View, FlatList } from 'react-native';
import WaterfallList from 'react-native-waterfall-flow'; 
import LottieView from 'lottie-react-native';

const CustomWaterfallWithLottie = () => {
  const [refreshing, setRefreshing] = useState(false);
  const [data, setData] = useState(['新闻1', '新闻2', '新闻3']);
  const scrollY = useRef(0); // 存储滚动的位置
  const isPulling = useRef(false); // 标识是否在下拉

  // 模拟刷新操作
  const onRefresh = useCallback(() => {
    setRefreshing(true);
    setTimeout(() => {
      setData([...data, `新闻${data.length + 1}`, `新闻${data.length + 2}`]);
      setRefreshing(false);
    }, 2000);
  }, [data]);

  const renderItem = ({ item, index }) => (
    <View key={index} style={{ padding: 20, borderBottomWidth: 1, borderColor: '#ccc' }}>
      <Text>{item}</Text>
    </View>
  );

  return (
    <View style={{ flex: 1 }}>
      <FlatList
        data={data}
        keyExtractor={(item, index) => index.toString()}
        renderItem={renderItem}
        numColumns={2}  // 瀑布流的列数
        onScroll={(event) => {
          const yOffset = event.nativeEvent.contentOffset.y;
          scrollY.current = yOffset; // 存储当前滚动位置

          // 检测下拉刷新
          if (yOffset < -100 && !refreshing && !isPulling.current) {
            isPulling.current = true;
            onRefresh(); // 开始刷新
          } else if (yOffset >= 0) {
            isPulling.current = false;
          }
        }}
        scrollEventThrottle={16} // 保证滚动事件频率
        ListHeaderComponent={
          // 如果正在刷新，显示Lottie动画
          refreshing ? (
            <View style={{ alignItems: 'center', marginVertical: 10 }}>
              <LottieView
                source={require('./assets/lottie-refresh.json')} 
                autoPlay
                loop
                style={{ height: 100 }}
              />
            </View>
          ) : null
        }
      />
    </View>
  );
};

export default CustomWaterfallWithLottie;