I have a small Box in a big Box. The large Box has a width of `Modifier.fillMaxWidth`. The small Box...

# compose

[Nat Strangerweather]

I have a small Box in a big Box. The large Box has a width of Modifier.fillMaxWidth. The small Box has a width of Modifier.fillMaxWidth(1 / 7f) . Elsewhere in my code outside my Composable I am defining an animation. There, I need the offset of my small Box to be the same as its width. Is there any way to use Modifier.fillMaxWidth as a variable? If not, how can I get the right width for my offset?

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

You can use Modifier.onSizeChanged to get the size of a composable once it’s measured, although the size won’t be available until after the first composition (might be fine depending on your animation).

Since your width is also fixed relative to your parent, you could also use BoxWithConstraints to get the max available width inside your big box and calculate the width for your child yourself (slightly less flexible, but available immediately).

[Nat Strangerweather]

Oh, ok, thanks I will look into that! 🙂

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

I think you might want to take a look at the AnimatedVisibility code – some of the available transition animations offset a component by its own width, so similar idea.

[Nat Strangerweather]

Nice, I really love Compose! ❤️

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

Me too! 😂