SectionList scrollToLocation does not scroll to the correct position

Description

When a SectionList contains a large number of items, calling scrollToLocation
scrolls to a slightly incorrect position, even though getItemLayout is properly provided.

Instead of scrolling exactly to the specified item, the list stops a bit offset from the expected location.

If this behavior is expected or if my usage of SectionList / getItemLayout is incorrect,
I would appreciate any guidance on the correct approach.

import React, { useRef, useMemo } from 'react';
import { SectionList, Text, View, Button } from 'react-native';

const HEADER_HEIGHT = 40;
const ITEM_HEIGHT = 30;

const TARGET_SECTION_INDEX = 20;

const generateSections = () => {
  const createItems = (prefix) => {
    const count = 20 + Math.floor(Math.random() * 100);
    return [...Array(count)].map((_, i) => ({
      label: `${prefix} Item ${i + 1}`,
    }));
  };

  return [...Array(24)].map((_, sectionIndex) => ({
    title: `Section ${sectionIndex + 1}`,
    data: createItems(`Section ${sectionIndex + 1}`),
  }));
};

export default function App() {
  const sectionListRef = useRef(null);
  const sections = useMemo(() => generateSections(), []);

  const scrollToSection = () => {
    if (sectionListRef.current) {
      sectionListRef.current.scrollToLocation({
        sectionIndex: TARGET_SECTION_INDEX,
        itemIndex: 0,
        viewPosition: 0,
      });
    }
  };

  return (
    <View style={{ flex: 1, paddingTop: 40 }}>
      <Button
        title={`Scroll to Section ${TARGET_SECTION_INDEX + 1}`}
        onPress={scrollToSection}
      />
      <SectionList
        ref={sectionListRef}
        sections={sections}
        keyExtractor={(item, index) => item.label + index}
        renderItem={({ item }) => (
          <View
            style={{
              height: ITEM_HEIGHT,
              justifyContent: 'center',
              borderBottomWidth: 1,
              borderColor: '#ccc',
            }}>
            <Text>{item.label}</Text>
          </View>
        )}
        renderSectionHeader={({ section: { title } }) => (
          <View
            style={{
              justifyContent: 'center',
              height: HEADER_HEIGHT,
              backgroundColor: '#eee',
            }}>
            <Text
              style={{
                fontWeight: 'bold',
              }}>
              {title}
            </Text>
          </View>
        )}
        getItemLayout={(_, index) => ({
          index,
          length: ITEM_HEIGHT,
          offset: ITEM_HEIGHT * index,
        })}
      />
    </View>
  );
}

Steps to reproduce

1. Render a SectionList
2. Call scrollToLocation with a valid sectionIndex and itemIndex
3. Observe the scroll position

React Native Version

0.81.4

Affected Platforms

Other (please specify), Runtime - Android

Output of npx @react-native-community/cli info

skip

Stacktrace or Logs

nothing

MANDATORY Reproducer

https://snack.expo.dev/@kuroppi/sectionlist-scrolltolocation

Screenshots and Videos

expected:

actual:

在 Android 上运行链接的 Snack 复现器，并将 SectionList.scrollToLocation 与提供的 getItemLayout 行为进行比较。首先跟踪 SectionList scrollToLocation 入口点以及对 sectionIndex 和 itemIndex 的处理。完成的标准是，请求的 section 和 item 在大型列表中到达预期位置。