react / react/react-native

Unexpected scroll behaviors when using FlatList

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Component: FlatList Issue: Author Provided Repro Needs: Attention Needs: Triage :mag: Newer Patch Available
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描述

Description

Content teleports to right when over-scrolling, if the content is less.

What I am trying to do? 🤔

Two FlatList components are nested inside a ScrollView for a custom component to emulate a grid like structure.

Example:

_________
         |
         |
[] [] [] | [] []
[] [] [] | [] []
[] [] [] | [] []
[] [] [] | []
         |
         |
▔▔▔▔▔

[] represent grid items and | represents edge of the screen. The items are accessed by scrolling horizontally.

How am I doing this? ❓

export function HorizontalRowList({
    rows, data, renderItem,
    bounces = false,
    itemSeparatorComponent,
    style, columnStyle
}) {
    const columns = divideArrayIntoChunks(rows, data);
    return (
        <ScrollView style={{ ...style, overflow: "hidden" }}
            showsVerticalScrollIndicator={false}
            nestedScrollEnabled={true}
            alwaysBounceHorizontal={bounces}
            bounces={bounces}>
            <FlatList data={columns}
                style={{ borderColor: "blue", borderWidth: 1, overflow: "hidden" }}
                ItemSeparatorComponent={itemSeparatorComponent}
                nestedScrollEnabled={true}
                legacyImplementation={false}
                initialNumToRender={columns.length}
                horizontal={true}
                alwaysBounceHorizontal={bounces}
                bounces={bounces}
                renderItem={(column) => {
                    return <FlatList data={column.item}
                        style={columnStyle}
                        ItemSeparatorComponent={itemSeparatorComponent}
                        legacyImplementation={false}
                        bounces={bounces}
                        renderItem={({ item }) => {
                            return renderItem(item);
                        }} />
                }} />
        </ScrollView >
    )
}
function divideArrayIntoChunks(chunkSize, array) {
    const chuckedArray = []
    for (let i = 0; i < array.length; i += chunkSize) {
        chuckedArray.push(array.slice(i, i + chunkSize))
    }
    return chuckedArray;
}

ScrollView to disable individual vertical scroll bars for the columns when the component has less space.
The first FlatList to enable horizontal behavior of grid
The second FlatList component are columns. The component can be given used to render list of varying sizes.

When the bug occurs? 🪲

The bug happens when data is less and rows to render are more. This causes the array to be chunked in the following way:

[] []     |
[] []     |
[] []     |
[]        |
Steps to reproduce
  • Create a new project
  • Add the code for HorizontalRowList component given in the description
  • Import and add the component in App.js
  • Create a random list of strings or any other object
  • Pass this list to data attribute of HorizontalRowList
  • Set the row attribute in such a way that there is considerable space to the right of the HorizontalRowList
  • Try scrolling HorizontalRowList and observe the behavior
React Native Version

0.73.6

Affected Platforms

Runtime - Android

Output of npx react-native info
System:
  OS: Windows 11 10.0.22631
  CPU: (8) x64 11th Gen Intel(R) Core(TM) i5-1155G7 @ 2.50GHz
  Memory: 5.68 GB / 15.78 GB
Binaries:
  Node:
    version: 21.0.0
    path: C:\Program Files\nodejs\node.EXE
  Yarn: Not Found
  npm:
    version: 10.4.0
    path: C:\Program Files\nodejs\npm.CMD
  Watchman: Not Found
SDKs:
  Android SDK: Not Found
  Windows SDK: Not Found
IDEs:
  Android Studio: Not Found
  Visual Studio:
    - 17.8.34408.163 (Visual Studio Community 2022)
Languages:
  Java: Not Found
  Ruby: Not Found
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.2.0
    wanted: 18.2.0
  react-native:
    installed: 0.73.6
    wanted: ^0.73.6
  react-native-windows: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: Not found
  newArchEnabled: Not found
iOS:
  hermesEnabled: Not found
  newArchEnabled: Not found
Stacktrace or Logs
No Errors
Reproducer

Please check this snack

https://staging-snack.expo.dev/kawPQ53xi5xNUpxnPKYfB

Screenshots and Videos

ezgif-1-f9032ba6fe

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  1. 先读完整个 Issue,再读项目的贡献指南。
  2. 在 Issue 下留言说明你要接手 —— 这能避免两个人做同样的事。
  3. Fork 仓库,在一个分支上完成修改。
  4. 提交 Pull Request,并在描述里引用这个 Issue 编号。

调研方向

从 App.js 中的 HorizontalRowList 示例和链接的 Snack 开始,使用 Android 上的 React Native 0.73.6。复现 ScrollView 和 FlatList 嵌套、数据少于请求行数的情况,然后跟踪滚动行为。当内容在过度滚动时不再水平瞬移,即表示完成。

由索引模型根据 Issue 内容生成。

评估

技术栈
javascript, react-native
领域
mobile
Issue 类型
缺陷
难度
4/5
预计耗时
3-5 天
活跃度
停滞
描述清晰度
基本清楚
新手友好度
35/100

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