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ContentView inherits from the wrong base Layout class

See original GitHub issue

Description

There are two parallel layout implementations in .NET MAUI:

The new layout implementation with the base class of Microsoft.Maui.Controls.Layout
The legacy layout implementation from Xamarin.Forms with the base class of Microsoft.Maui.Controls.Compatibility.Layout

The new layout implementation is compatible with the new MAUI handlers. The old layout implementation from Xamarin.Forms is not compatible with the handlers and should be avoided.

The problem with the ContentView is that it has a handler, but is still inherits from the legacy layout Microsoft.Maui.Controls.Compatibility.Layout. This is a major source of bugs, as the usual layout logic might not be executed correctly or might not get executed at all on some platforms.

Steps to Reproduce

Download and run the attached sample project on Windows.

TestApp.zip

The sample project contains a single CustomView inheriting from ContentView. The sole purpose of that CustomView is to override all the virtual Measure, Arrange, Layout etc. methods of the base class and dump some debug output when they are called. The sample applications has two additional buttons to call the InvalidateMeasure method on the CustomView from the base VisualElement class and from the IView interface.

Observe the debug output of the application. You can also put breakpoints in the overridden methods to be sure. Notice that nothing happens: nothing is called at all. All the layout logic of the CustomView is completely discarded.

Version with bug

6.0 (current)

Last version that worked well

Unknown/Other

Affected platforms

Windows

Affected platform versions

N/A

Did you find any workaround?

Unless Microsoft changes the implementation of the ContentView to inherit from the new Microsoft.Maui.Controls.Layut and implements the necessary glue code, I cannot suggest any viable workaround, except not using ContentView or any templated controls in the .NET MAUI applications.

Relevant log output

No response

Issue Analytics

State:
Created a year ago
Reactions:1
Comments:7 (1 by maintainers)

Top GitHub Comments

2reactions

msftbot[bot]commented, Aug 30, 2022

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.

2reactions

drasticactionscommented, May 30, 2022

Wouldn’t this be an issue with the Telerik controls you’re using? I’m not sure how this is a MAUI issue.

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