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kotlinlang

Just saw that a new <https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/layout/OnRectChangedModifier.kt;l=56?q=onRectChanged()&amp;sq=|onRectChanged> modifier was created. What are the use cases for such a modifier?
And provided you do not use the debounce/throttle params, when would one use this over onPlaced or onGloballyPositioned (depending on what info you need)?

It is part of a new set of APIs to track visibility/occlusion of nodes. To measure impressions for instance 

I think it is intended to be a more performant replacement for onGloballyPositioned as well

If you need to track things like scrolling and such, yes absolutely

Which use cases would onGloballyPositioned still be useful for then?
Is it just a strictly better version of it, or did it have to compromise on some information it provides to you to get that better performance?

I think it is a strictly better version, but maybe I am missing some cases

Is there a phase ordering guarantee for `onRectChanged`?

Ah “This will be called after layout pass.” (reading the docs closer)

omg does this mean `focusable()` can finally stop observing `onGloballyPositioned`?

The author says “yes please” to the question of “should folks use onRectChanged instead of onGloballyPositioned”. We’ll try though to implement onGloballyPositioned on top of onRectChanged

Well, I am really glad I asked! Thanks for all the info everyone

Really excited for this one, I was about to dive into the weeds of benchmarking a modifer we use for impression analytics that uses `onGloballyPositioned` and here you just offer me a solution to all my concerns with our current implementation :heart:

There's gonna be APIs on top of this specifically to let you know about visibility. That's what you'll want to use 