:android-wave: Is there a way to measure a child b...

# compose

[Chris Johnson]

👋 Is there a way to measure a child before placing it and then fill the screen with the available amount of those children? Currently I'm creating a Layout for measurement of the child and then another Layout that will place X amount of those children based on screen height. The problem I ran into was each child I'm placing needs to be unique/not being currently laid out for the system to not give me "Place was called on a node which was placed already".

[Zach Klippenstein (he/him) [MOD]]

I think SubcomposeLayout might be your best bet here. You basically described how the lazy lists work.

[Zach Klippenstein (he/him) [MOD]]

You can use it to subcompose+measure the first child, then subcompose+etc as many other children as you need.

[Chris Johnson]

I thought about a SubcomposeLayout . Was sure that I would run into the same issue of not being able to place the same placeable. But now that I'm looking at it more calling subcompose would allow me to create a new placeable to place which should solve that. I'll try that next!
Zach to the rescue again. 🦸

[Zach Klippenstein (he/him) [MOD]]

yep exactly, you can just call subcompose multiple times with the same content function

[Chris Johnson]

Sweet. That composable is so powerful

[Chris Johnson]

Now for the harder question of... which is better for performance? Having a Layout that gets the measure and is then removed from composition via a mutableStateOf(Boolean) + a Layout to place.
Or using Subcomposelayout

[Chris Johnson]

Time to get out the profiler... 😱

[Zach Klippenstein (he/him) [MOD]]

Before even considering performance, those will do different things. The former will not show the content until the second frame, which will most likely look noticeably bad.

[Chris Johnson]

You don't really notice it, but yes you're right it would have to go through re-composition to show. Subcomposelayout seems to do the trick beautifully 🙂

[Zach Klippenstein (he/him) [MOD]]

There can be other negative effects of skipping that first frame (e.g. it breaks the IDE preview)