[expo-optimize] Removes alpha channel

[janaagaard75]

Running npx expo-optimize removed the alpha channel on this image: https://github.com/janaagaard75/desert-walk/blob/master/assets/50713-transparent.png.

(I hope this is enough information to reproduce the bug.)

[janaagaard75]

I played around with the the command options for sharp-cli, but adding --alphaQuality 100 or --quality 100 still produced the same optimized image, that doesn't have an alpha channel / or a quite different alpha channel.

I created an issue on the sharp-cli project: vseventer/sharp-cli#31, hoping that they can help.

Update: sharp-cli sent me to sharp, so the issue above has been superseded with this one: lovell/sharp#2013.

[janaagaard75]

The issue in Sharp (lovell/sharp#2013) is fixed, but it hasn't been released yet. Keeping this issue open until then.

[janaagaard75]

A new version of sharp has been released fixing lovell/sharp#2013, so now we have to wait for an update to sharp-cli that references this updated version of sharp.

[janaagaard75]

sharp-cli has just been updated, so this issue can finally be closed.

(I would be nice if expo-optimzed used sharp directed instead of through sharp-cli, because that sharp is updated more often, and it would remove the necessity to install sharp-cli. I have no idea about how big a task this is, though.)