React-native: RCTView: Shadow warnings with transparent backgrounds

[a-koka]

Description

RCTView throws warnings when trying to set shadows on components with transparent backgrounds.

Reproduction

Assign the following style to any Component.

const styles = StyleSheet.create({
  shadowWithWarning: {
    backgroundColor: 'transparent',
    shadowColor: '#555',
    shadowOpacity: 0.5,
    shadowRadius: 2,
    shadowOffset: {
      height: 2,
      width: 1
    }
  }

Solution

Although RCTView complains about not being able to calculate the shadow efficiently, the shadows render just fine. Would be great to be able to suppress this warning.

Additional Information

• React Native version: 0.39.2
• Platform: iOS
• Operating System: MacOS

[prithsharma]

I am also facing the same warning for backgroundColor as transparent - in fact, for backgroundColor with any opacity other than 1(using rgba).
While this commit explains the reason for the warning, but says nothing about a solution for using transparent backgrounds in a performant way other than not using transparent backgrounds.

For people who don't have enough native iOS knowledge, can someone please clarify if using transparent backgrounds on iOS is actually non-performant and should be avoided or this is a limitation of the current RN implementation of shadows(and would be fixed in a later version)?

EDIT - On closer observation, it seems this warning comes up when using transparent backgroundColor with shadow. Removing shadow(or setting shadowOpacity as 0) makes the warning go away.

[hramos]

Hi there! This issue is being closed because it has been inactive for a while. Maybe the issue has been fixed in a recent release, or perhaps it is not affecting a lot of people. Either way, we're automatically closing issues after a period of inactivity. Please do not take it personally!

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If you would like to work on a patch to fix the issue, contributions are very welcome! Read through the contribution guide, and feel free to hop into #react-native if you need help planning your contribution.

[adamnator92]

@prithsharma the warning gone after i apply shadowOpacity: 0

[himelnagrana]

@prithsharma @Adamnator92
in my case it solved by putting:
shadowOpacity: 0.9

The look is almost same but removes the warning.