react / react/react-native

[Android] Incorrect border coloration with sufficiently high border radius

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Issue: Author Provided Repro Needs: Triage :mag: Platform: Android
Dominant language
C++
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Description

Description

It seems Android has trouble displaying the correct border colors when borderRadius exceeds a certain value.

The use case here is having an easily reusable style or component which can be circular regardless of the size; most easily achieved by setting a high border radius. Given that this works as intended on iOS and web, I assume it is a supported use case. If border radius is not intended to exceed a certain calculable value it should be noted in the docs somewhere but I was unable to find any relevant information. Alternatively, It might make sense to clamp the value in the RN core code but I'll leave that to the maintainers to decide.

Based on my testing this issue only impacts Android as you can see in the screenshots from the snack I've linked below.
Web:
Screenshot 2023-11-29 at 9 02 21 AM
iOS:
Screenshot 2023-11-29 at 9 02 06 AM
Android:
Screenshot 2023-11-29 at 8 59 58 AM

I've seen some other recent issues around border radius on Android but none of them seem to be directly related to this particular behavior based on my understanding so apologies if this is a duplicate, obviously feel free to close/merge in that case.

React Native Version

0.72.7

Output of npx react-native info

System:
OS: macOS 13.6
CPU: (10) arm64 Apple M1 Max
Memory: 2.82 GB / 64.00 GB
Shell:
version: "5.9"
path: /bin/zsh
Binaries:
Node:
version: 18.16.0
path: ~/.nvm/versions/node/v18.16.0/bin/node
Yarn:
version: 1.22.19
path: ~/.nvm/versions/node/v18.16.0/bin/yarn
npm:
version: 9.5.1
path: ~/.nvm/versions/node/v18.16.0/bin/npm
Watchman:
version: 2023.10.23.00
path: /opt/homebrew/bin/watchman
Managers:
CocoaPods:
version: 1.14.2
path: /opt/homebrew/opt/ruby/bin/pod
SDKs:
iOS SDK:
Platforms:
- DriverKit 23.0
- iOS 17.0
- macOS 14.0
- tvOS 17.0
- watchOS 10.0
Android SDK: Not Found
IDEs:
Android Studio: 2022.2 AI-222.4459.24.2221.9971841
Xcode:
version: 15.0.1/15A507
path: /usr/bin/xcodebuild
Languages:
Java:
version: 17.0.2
path: /usr/bin/javac
Ruby:
version: 3.2.2
path: /opt/homebrew/opt/ruby/bin/ruby
npmPackages:
"@react-native-community/cli": Not Found
react:
installed: 18.2.0
wanted: 18.2.0
react-native:
installed: 0.72.7
wanted: 0.72.7
react-native-macos: Not Found
npmGlobalPackages:
"react-native": Not Found
Android:
hermesEnabled: true
newArchEnabled: false
iOS:
hermesEnabled: true
newArchEnabled: false

Steps to reproduce
  1. Create a <View />.
  2. Give the view different colors for each of borderTopColor, borderBottomColor, borderRightColor, and borderLeftColor
  3. Set the view's height and width to any number, n
  4. Set the view's borderRadius to any number greater than n/2
  5. Observe the coloration of the border. Optionally, you can change the borderRadius value to see how the colors change with different values.
Snack, screenshot, or link to a repository

https://snack.expo.dev/gl3ZjJQi1

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 Snack and reproducing the Android behavior with different border colors and a borderRadius greater than half the view size. Trace the Android React Native border-rendering entry point, then verify the result against the iOS and web screenshots; done means the Android border colors remain correct for the reported radius case.

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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