Arrange on Layouts not respecting correctly the passed bounding Rect

[ivan-todorov-progress]

Description

Simply put, Arrange should not assume that the passed bounding Rect has the same Size as the passed size constraints on Measure. For instance, it is completely valid to call Measure with 200x100 size constraints, but then call Arrange with a 400x300 bounding Rect. The actual available Size is often not known during Measure, but is only available during Arrange.

What happens in practice is, when Measure is called on a Layout with some finite size constraints, the Layout remembers the measured size in the DesiredSize property and uses that during Arrange, disregarding the actual size passed with the bounding Rect.

Steps to Reproduce

Download an run the attached sample project.

TestApp.zip

The sample project contains a CustomLayout, which is used to demonstrate the incorrect behavior. The CustomLayout simply calls Measure and Arrange on its only child forwarding the passed parameters. The content of the CustomLayout is a Grid with a Label, which is centered inside the Grid. The CustomLayout has a bool property to control whether to pass the original size constraints when measuring the child or double.PositiveInfinity. Observe how the child Grid behaves differently on Arrange, depending on the arguments passed on Measure, even though we pass the same bounding Rect during Arrange. I have set a BacgroundColor on the Grid to demonstrate that the Grid is arranged correctly in both cases.

The following screenshot illustrates the behavior with finite size constraints on Measure (the Label is centered in the Grid):

The next screenshot demonstrates the behavior with infinite size constraints on Measure (the Label is not centered in the Grid):

Version with bug

6.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

iOS, Android, Windows, macOS

Affected platform versions

N/A

Did you find any workaround?

One semi-working workaround is to call Measure of the child during Arrange with the final size constraints. This crashes on Windows with an infinite layout loop however. ;-)

Relevant log output

No response

[kristinx0211]

verified repro on android with above repro project.

[ghost]

We've moved this issue to the Backlog milestone. This means that it is not going to be worked on for the coming release. We will reassess the backlog following the current release and consider this item at that time. To learn more about our issue management process and to have better expectation regarding different types of issues you can read our Triage Process.

[hartez]

This is now working as expected in with 6.0.400.