From a performance perspective, how horrendous is ...

# compose

[chris-horner]

From a performance perspective, how horrendous is it to have Layout { } invoked every frame? Especially with lots of temporary collections being created with lines like

val placeables = measurables.map { it.measure(constraints) }

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

I think there’s some guidance that it’s best to avoid animating layouts when possible. But if you do just need to animate a layout, they’re generally cheap enough in compose that it might be fine. In particular, compose layouts (at least the basic ones) are less expensive than view layouts.

It also might be possible to avoid both recomposing and invalidating the layout on each frame, but that’s probably not worth bothering to do unless you’ve got evidence that that’s what’s causing jank.

[chris-horner]

I’m currently making some real hacky code where I essentially want to wire up Layout to Box2D and have composables bounce off each other 😅

Ideally with an API that looks something like

Physics {
  Button()
  Text()
}

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

I think it would be better to do this with graphicsLayer offsets - that way you’re just moving hardware layers around and not triggering layout or draw passes on each frame, if I understand correctly.

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

And you’ll want to use the lambda version of graphicsLayer not the parameter one

[chris-horner]

Oooo, interesting 🤔. Any limitations on the number of graphics layers that can be around at once?

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

I have no idea. At some point even if there’s no hard limit I’d expect the overhead would start to show as well, and I’m not sure if you’d hit that sooner with layers or layouts. Would be fun to implement both then just keep adding children until you notice frames dropping and compare.

[chris-horner]

Definitely sounds like graphicsLayer { } is the place to start! Thanks for the help yet again

[chris-horner]

If I wanted to aim for the API to look like what I mentioned above, is there a way I could cheekily update the modifiers of every composable passed in?

[Albert Chang]

Also if your layout is invoked very often, using compose versions of list utils (e.g. fastForEach, fastMap) from ui-util module can at least reduce the number of temporary objects.

[Adam Powell]

When you want to be manipulating more than one child element relative to each other with one source of truth performing the coordination, Layout is the way to go. In the placement block you can do placeable.placeWithLayer which is identical to giving that child a graphicsLayer to add whatever additional effects you like.

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

Oh right I always forget about that

[chris-horner]

Early placeable.placeWithLayer experiments are promising 😄

Screen Recording 2021-09-15 at 13.55.07.mov

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

Haha I love it!

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

Angry Buttons

[Adam Powell]

That's pretty great

[Stylianos Gakis]

Wait this is actually hilarious and amazing at the same time, I have never seen anyone else share something similar to this before mind blown