Hello everybody. I have a more technical question...

# compose

[Matej Drobnič]

Hello everybody.

I have a more technical question regarding the layouting of compose. From documentation, compose has no double measuring. Instead, intrinsics are to be used.

However, from what I see in the source code, by default, intrinsics just calls measure: https://cs.android.com/androidx/platform/frameworks/support/+/androidx-main:compose/ui/ui/src/commonMain/kotlin/androidx/compose/ui/layout/MeasurePolicy.kt;l=138

What is the main difference then?

Additionally, isn't that even worse than measuring? For example, if I want both max width and max height of some composable, before I do the final measure, I have to call both intrinsic methods, which will internally call measure twice, instead of just directly calling measure, which would give me both values in one call (but I'm not allowed to do that before final measure).

Thanks.

[Matej Drobnič]

After some digging, it appears that layouts like Column and Row define their own intrinsics

[Matej Drobnič]

However, some layouts, like Flow, do not: https://github.com/google/accompanist/blob/main/flowlayout/src/main/java/com/google/accompanist/flowlayout/Flow.kt

[Matej Drobnič]

does that mean that flow will be significantly slower, since it will have to perform full measure for every intrinsic call?

[Albert Chang]

if I want both max width and max height of some composable

Intrinsic size is the max/min width/height at a fixed height/width, respectively. Usually you just use one of the four intrinsic sizes. Why do you need both max width and max height?

since it will have to perform full measure for every intrinsic call

It's not full measure. Children that override intrinsic size methods (e.g. Text) can be measured faster.

[Matej Drobnič]

I see

[Matej Drobnič]

but if one were to implement, let's say, constraint layout, one would need both intrinsics, right?

[Matej Drobnič]

to measure for all constraints

[Albert Chang]

ConstraintLayout is the only MultiMeasureLayout. I don't think there's any layout you need to implement yourself using that.

[Matej Drobnič]

I see

[Matej Drobnič]

thanks for your answers