fix: measure content height on layout change

[eduardomoroni]

When you were with collapsible opened (state.collapsed = false) and children changes it's height, Collapsible component was breaking the layout.

[iRoachie]

Hey I think your PR looks good, can you just create a small example repo so I could see this in action? A before and after?

[eduardomoroni]

Hey @iRoachie, could I sent you a GIF? Reproduce this error might take a while and I don't have too much time lately :/

[iRoachie]

Sure that works, just make sure in the gif you can see both:

• the problem (before your PR)
• the solution (after your PR)

[ayushinigam]

Hi @iRoachie,
I can confirm that the PR works. It fixes the issue of re measuring the height on layout change.
It would be really helpful if you could merge it.

Thanks

[eduardomoroni]

Sorry guys, didn't have cycles to create a GIF or an example showing this working, could help us with that @ayushinigam?

[iRoachie]

@ayushinigam I would love to merge this PR if it fixes a problem. I just need to be sure what it's supposed to fix, and if it accurately does that. This is the reasoning behind asking for an example app maybe to be made so that the changes can be observed

[oliverdolgener]

@iRoachie why was this feature reverted? I have the same problem: I am using the Collapsible with a FlatList as child that gets updated dynamically while the collapsible is not collapsed resulting in a wrong height calculation. The added items are shown only when collapsing and reopening the list.

[iRoachie]

@oliverdolgener because of #168

[oliverdolgener]

@iRoachie oh that's too bad! But I understand the problems this caused. Do you have an idea for my problem? Is there a function I could call upon receiving new data to update the collapsible height?

[oliverdolgener]

@iRoachie I solved the problem by replacing my FlatList with a simple map() function. Not the most beautiful solution but it works!

[papigers]

For those who still have this problem, I've found a little hack that should be better than replacing FlatList with map() (especially for long lists).
Set the initial value for collapsed to be false, and use componentDidMount/useEffect/useFocusEffect (=react-navigation) to set the collapsed value to be true on mount or screen focus.
The only downside (which I don't really consider as a downside but still) is that the user sees the initial uncollapse animation.

[wmonecke]

This PR introduces flickering. Anyone else experiencing the same?