react / react/react-native

Using absolute positioning, when the parent element has padding, the width height of the current element is incorrectly laid out using a percentage layout

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Issue: Author Provided Repro
Dominant language
C++
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Description

Description
/**
 * Sample React Native App
 * https://github.com/facebook/react-native
 *
 * @format
 */

import React from 'react';
import {
  SafeAreaView,
  ScrollView,
  StatusBar,
  useColorScheme,
  View,
} from 'react-native';

function App(): React.JSX.Element {
  const isDarkMode = useColorScheme() === 'dark';

  const backgroundStyle = {
    backgroundColor: '#eee',
  };

  return (
    <SafeAreaView style={backgroundStyle}>
      <StatusBar
        barStyle={isDarkMode ? 'light-content' : 'dark-content'}
        backgroundColor={backgroundStyle.backgroundColor}
      />
      <ScrollView>
        <View
          style={{
            backgroundColor: '#000',
            height: 300,
            paddingTop: 200,
            paddingLeft: 200
          }}>
          <View style={{
            position: 'absolute',
            // width height 100%会排除父元素的padding
            width: '100%', height: '100%', left: 0, top: 0,
            backgroundColor: '#666'
          }} />
        </View>
      </ScrollView>
    </SafeAreaView>
  );
}

export default App;

WX20240909-101807

In the new architecture, I set the height to 100%, but its height is not equal to the height of the parent container, but will subtract the padding of the parent container

Steps to reproduce

1

React Native Version

0.75.2

Affected Platforms

Runtime - Android, Runtime - iOS

Areas

Fabric - The New Renderer

Output of npx react-native info
System:
  OS: macOS 14.5
  CPU: (16) x64 Intel(R) Core(TM) i7-10700 CPU @ 2.90GHz
  Memory: 35.26 MB / 32.00 GB
  Shell:
    version: "5.9"
    path: /bin/zsh
Binaries:
  Node:
    version: 18.20.3
    path: /private/var/folders/rf/gd60z12164z72bny7z_0d4f80000gn/T/xfs-de932bea/node
  Yarn:
    version: 3.6.4
    path: /private/var/folders/rf/gd60z12164z72bny7z_0d4f80000gn/T/xfs-de932bea/yarn
  npm:
    version: 10.7.0
    path: ~/.nvm/versions/node/v18.20.3/bin/npm
  Watchman:
    version: 2024.07.15.00
    path: /usr/local/bin/watchman
Managers:
  CocoaPods:
    version: 1.15.2
    path: /usr/local/bin/pod
SDKs:
  iOS SDK:
    Platforms:
      - DriverKit 23.5
      - iOS 17.5
      - macOS 14.5
      - tvOS 17.5
      - visionOS 1.2
      - watchOS 10.5
  Android SDK: Not Found
IDEs:
  Android Studio: 2024.1 AI-241.18034.62.2412.12266719
  Xcode:
    version: 15.4/15F31d
    path: /usr/bin/xcodebuild
Languages:
  Java:
    version: 17.0.11
    path: /usr/bin/javac
  Ruby:
    version: 2.6.10
    path: /usr/bin/ruby
npmPackages:
  "@react-native-community/cli": Not Found
  react:
    installed: 18.3.1
    wanted: 18.3.1
  react-native:
    installed: 0.75.1
    wanted: 0.75.1
  react-native-macos: Not Found
npmGlobalPackages:
  "*react-native*": Not Found
Android:
  hermesEnabled: true
  newArchEnabled: true
iOS:
  hermesEnabled: Not found
  newArchEnabled: false
Stacktrace or Logs
empty
Reproducer

https://github.com/ShaoGongBra/rn-test

Screenshots and Videos

No response

Contributor guide

Open the contributing guide

First steps

  1. Read the whole issue, then the project's contributing guide.
  2. Comment on the issue to say you are picking it up — it saves two people doing the same work.
  3. Fork the repository and make your change on a branch.
  4. Open a pull request that references the issue number.

Research direction

Start with the linked rn-test reproducer and the sample App component in the issue, using React Native 0.75.2 with Fabric enabled on Android and iOS. Reproduce the percentage sizing behavior with a padded parent, then trace the Fabric layout path to determine where the child dimensions diverge. Done means the absolute child’s 100% width and height match the parent container as expected.

Written by the indexing model from the issue text.

Assessment

Tech stack
javascript, react-native
Domain
mobile
Issue type
Bug
Difficulty
4/5
Estimated time
3-5 days
Activity status
Stale
Clarity
Mostly clear
Newbie friendliness
35/100

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