react / react/react-native

[Android] Tapping selectable text inside a ScrollView can cause the ScrollView to jump to the top under some circumstances

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Component: ScrollView Needs: Triage :mag: Never gets stale Platform: Android
Dominant language
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Description

Description

After selectable text inside a ScrollView has been touched in a way that neither creates a selection nor scrolls the ScrollView, certain interactions cause the ScrollView to scroll to the top.
(I'm not sure exactly what set of events are necessary to trigger the jump, but I have a text unloading algorithm that consistently causes it. The issue may be specific to large or nested Texts, and may have to do with content changing as the result of a scroll event? Changing the content of the text in a setInterval didn't seem to be enough to cause it, so I just copied the unloading algorithm out of my codebase.)

As a workaround, updating the key prop on the selectable text component seems to clear the glitched state.

Version

0.67.3 (originally observed on 0.64.1)

Output of npx react-native info
info Fetching system and libraries information...
System:
    OS: Windows 10 10.0.22000
    CPU: (12) x64 Intel(R) Core(TM) i7-10750H CPU @ 2.60GHz
    Memory: 3.72 GB / 15.76 GB
  Binaries:
    Node: 17.7.1 - C:\Program Files\nodejs\node.EXE
    Yarn: 1.22.5 - C:\Program Files (x86)\Yarn\bin\yarn.CMD
    npm: 8.5.2 - 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: 16.10.31402.337 (Visual Studio Community 2019), 15.9.28307.1033 (Visual Studio Community 2017)
  Languages:
    Java: 1.8.0_282 - C:\Program Files\OpenJDK\openjdk-8u282-b08\bin\javac.EXE
  npmPackages:
    @react-native-community/cli: Not Found
    react: 17.0.2 => 17.0.2
    react-native: 0.67.3 => 0.67.3
    react-native-windows: Not Found
  npmGlobalPackages:
    *react-native*: Not Found
Steps to reproduce
  1. Run the Snack below on an Android device (Snack's provided one or your own).
  2. Scroll up and down; observe that scrolling works as expected.
  3. Tap on the text without starting a selection or scrolling. (Tapping to cancel a selection works.)
  4. Try scrolling again; observe that the scroll jumps to the top now.
Snack, code example, screenshot, or link to a repository

https://snack.expo.dev/b2Vgmc_4L
Set USE_WORKAROUND to true to see the workaround in action (this breaks the ability to actually select text, but if you need to use this in production, you can use https://github.com/artemiswkearney/react-native-selectable-text to add an onSelectionStart handler where you cancel running the workaround)

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 by running the linked Expo Snack on an Android device and follow its scrolling and tapping steps, including the USE_WORKAROUND option. Investigate the Android ScrollView and selectable text interaction described in the reproduction. Done means scrolling no longer jumps to the top after an otherwise non-selecting tap, while text selection still works without the workaround.

Written by the indexing model from the issue text.

Assessment

Tech stack
android, 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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