@stream-io/flat-list-mvcp/lib/module/FlatList.android.js

`maintainVisibleContentPosition` support for Android react-native

function _extends() { _extends = Object.assign || function (target) { for (var i = 1; i < arguments.length; i++) { var source = arguments[i]; for (var key in source) { if (Object.prototype.hasOwnProperty.call(source, key)) { target[key] = source[key]; } } } return target; }; return _extends.apply(this, arguments); }

import React, { useEffect, useRef } from 'react';
import { FlatList, NativeModules, Platform } from 'react-native';
export const ScrollViewManager = NativeModules.MvcpScrollViewManager;
export default /*#__PURE__*/React.forwardRef((props, forwardedRef) => {
  var _props$maintainVisibl, _props$maintainVisibl2;

  const flRef = useRef(null);
  const isMvcpEnabledNative = useRef(false);
  const handle = useRef(null);
  const enableMvcpRetriesCount = useRef(0);
  const isMvcpPropPresentRef = useRef(!!props.maintainVisibleContentPosition);
  const autoscrollToTopThreshold = useRef(((_props$maintainVisibl = props.maintainVisibleContentPosition) === null || _props$maintainVisibl === void 0 ? void 0 : _props$maintainVisibl.autoscrollToTopThreshold) || -Number.MAX_SAFE_INTEGER);
  const minIndexForVisible = useRef(((_props$maintainVisibl2 = props.maintainVisibleContentPosition) === null || _props$maintainVisibl2 === void 0 ? void 0 : _props$maintainVisibl2.minIndexForVisible) || 1);
  const retryTimeoutId = useRef();
  const debounceTimeoutId = useRef();
  const disableMvcpRef = useRef(async () => {
    isMvcpEnabledNative.current = false;

    if (!(handle !== null && handle !== void 0 && handle.current)) {
      return;
    }

    await ScrollViewManager.disableMaintainVisibleContentPosition(handle.current);
  });
  const enableMvcpWithRetriesRef = useRef(() => {
    // debounce to wait till consecutive mvcp enabling
    // this ensures that always previous handles are disabled first
    if (debounceTimeoutId.current) {
      clearTimeout(debounceTimeoutId.current);
    }

    debounceTimeoutId.current = setTimeout(async () => {
      // disable any previous enabled handles
      await disableMvcpRef.current();

      if (!flRef.current || !isMvcpPropPresentRef.current || isMvcpEnabledNative.current || Platform.OS !== 'android') {
        return;
      }

      const scrollableNode = flRef.current.getScrollableNode();

      try {
        const _handle = await ScrollViewManager.enableMaintainVisibleContentPosition(scrollableNode, autoscrollToTopThreshold.current, minIndexForVisible.current);

        handle.current = _handle;
      } catch (error) {
        /**
         * enableMaintainVisibleContentPosition from native module may throw IllegalViewOperationException,
         * in case view is not ready yet. In that case, lets do a retry!! (max of 10 tries)
         */
        if (enableMvcpRetriesCount.current < 10) {
          retryTimeoutId.current = setTimeout(enableMvcpWithRetriesRef.current, 100);
          enableMvcpRetriesCount.current += 1;
        }
      }
    }, 300);
  });
  useEffect(() => {
    var _props$maintainVisibl3, _props$maintainVisibl4;

    // when the mvcp prop changes
    // enable natively again, if the prop has changed
    const propAutoscrollToTopThreshold = ((_props$maintainVisibl3 = props.maintainVisibleContentPosition) === null || _props$maintainVisibl3 === void 0 ? void 0 : _props$maintainVisibl3.autoscrollToTopThreshold) || -Number.MAX_SAFE_INTEGER;
    const propMinIndexForVisible = ((_props$maintainVisibl4 = props.maintainVisibleContentPosition) === null || _props$maintainVisibl4 === void 0 ? void 0 : _props$maintainVisibl4.minIndexForVisible) || 1;
    const hasMvcpChanged = autoscrollToTopThreshold.current !== propAutoscrollToTopThreshold || minIndexForVisible.current !== propMinIndexForVisible || isMvcpPropPresentRef.current !== !!props.maintainVisibleContentPosition;

    if (hasMvcpChanged) {
      enableMvcpRetriesCount.current = 0;
      autoscrollToTopThreshold.current = propAutoscrollToTopThreshold;
      minIndexForVisible.current = propMinIndexForVisible;
      isMvcpPropPresentRef.current = !!props.maintainVisibleContentPosition;
      enableMvcpWithRetriesRef.current();
    }
  }, [props.maintainVisibleContentPosition]);
  const refCallback = useRef(ref => {
    flRef.current = ref;
    enableMvcpWithRetriesRef.current();

    if (typeof forwardedRef === 'function') {
      forwardedRef(ref);
    } else if (forwardedRef) {
      forwardedRef.current = ref;
    }
  }).current;
  useEffect(() => {
    const disableMvcp = disableMvcpRef.current;
    return () => {
      // clean up the retry mechanism
      if (debounceTimeoutId.current) {
        clearTimeout(debounceTimeoutId.current);
      } // clean up any debounce


      if (debounceTimeoutId.current) {
        clearTimeout(debounceTimeoutId.current);
      }

      disableMvcp();
    };
  }, []);
  return /*#__PURE__*/React.createElement(FlatList, _extends({}, props, {
    ref: refCallback
  }));
});
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