How to understand

measurement

and

intrinsic measurement

?

Measurement is, "given these width and height constraints, what size are you?" and intrinsic measurement is, "given that your width would be X, how tall would you need to be?" and the same for height/wide. Intrinsic measurement is meant to be a lighter weight alternative to full multi-pass speculative measurement to answer the same questions.

It sounds like a better approach for the case when a Parent dimension is wrap_content and the Child wants to match_parent. Is there an equivalent to:

requestLayout()

and

invalidate()

that ones can call when the shape or content of a composable change? Or there is no need for that?

Intrinsic measurement is just a series of functions available that a parent can call on a measurable (child) when the parent is in its own measure or layout phases.

Got it. I thought the fact of explicitly telling the ViewTree if you want a

requestLayout

or

invalidate

or both, optimized things a bit. Like calling only

invalidate

explicitly tell the system to skip measurement/layout phases.

it does, and the

@Model

observation scopes perform the same duty here for triggering what phase we need to go back to

I see, It makes lot of sense. Thanks

it does mean that these things get kind of subtle for the layout/draw code author. Capturing the value of an

@Model

outside the scope of where you actually use it means you can end up causing more work than you intended when it changes. You want to read

@Model

as close to the usage site as possible.

Good point