The `drawLayer` modifier is real nice! <https://gist.github.com/zach-klippenstein/e2c8e6edf0d950d8ba...

# compose

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

The drawLayer modifier is real nice!
https://gist.github.com/zach-klippenstein/e2c8e6edf0d950d8ba527cd0681c5b60

[romainguy]

Can you say more about this comment:

[romainguy]

“// Animating the alpha just look janky.”

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

Sorry, it works fine – I meant it just looks weird to have the alpha bouncing around. It’s not obvious that it’s animating, it just looks strange.

[romainguy]

Ok thanks! Just wanted to make sure it wasn’t an issue on our side 🙂

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

Nope, alpha works as expected. However, there is an issue with x/y rotation when the scale is too big: when the rotation is around 90º, lots of weird clipping or something starts to happen. This looks weird for other reasons (views are basically unreadable), so I don’t know why an app would try to do this in production, but I can file a bug.

clipping.mp4

[romainguy]

I am not surprised by this

[romainguy]

These are fake 3D rotations and I can definitely think of a few ways that they would catastrophically break down at such acute angles in Skia

[romainguy]

Please file a bug if you want but it’s not Compose specific

[romainguy]

I can forward this to one of the graphics engineers

[romainguy]

What version of Android is this on?

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

Android 10, March 5 2020 security patch, build QQ2A.200305.002

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

I'm not worried about it, doesn't seem like it would be an issue in real apps

[romainguy]

Thanks

[romainguy]

Yeah but still awkward

[Klaas Kabini]

@Zach Klippenstein (he/him) [MOD] This is a pretty interesting demonstration of the drawLayer modifier. Thanks for this dude

[louiscad]

I totally see that being used in an app onboarding

[Adam Powell]

since someone asked on twitter, no, this doesn't support transforming the input events - yet. 🙂 We were just discussing unifying transformations for layout/drawing/input earlier this week

[Adam Powell]

might end up being a slightly different modifier API that uses drawLayer as an implementation detail to get the visual part.

[Adam Powell]

not sure yet

[romainguy]

We filed a bug internally, the Skia team will investigate. Thanks for the repro case!

[Val Salamakha]

Zack, what kind of compose do you use? I cannot access default buttons as Add and others (dev-07) - only Favourite, Menu and Close available.

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

You need the material icons dependency as well: androidx.ui:ui-material-icons-extended:${versions.compose}

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

@romainguy I just noticed that the shadow under the FAB doesn’t rotate around the Z axis with the rest of the views – it’s always “below” the button relative to the screen, at every angle. I’m guessing that’s because the shadow has its own layer?

[romainguy]

yep

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

Really obvious here

[Val Salamakha]

Thanks, Zach

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

It's a bit of a contrived use case, but this is the demo I wanted to write when I first saw this composable 😂 made me think of the new layout inspector's 3D view

https://kotlinlang.slack.com/archives/C0BJ0GTE2/p1585585754055600

[romainguy]

The bug is confirmed fixed in Android R btw

[Bernardo Ferrari]

can’t we have skia updatable via project mainline to avoid issues like this in the future?

[romainguy]

It’s in the works

[Bernardo Ferrari]

Android S.. S of Skia.. lol, can’t wait! haha
(sidenote: unfortunately my device won’t receive it, but hopefully until then Samsung will be giving more than 2 major updates)