[Android] StackPanel does not use the return of child Arrange causing aligment issues

[dr1rrb]

Current behavior

With the visual tree:

<Setter Property="ItemsPanel">
    <Setter.Value>
        <ItemsPanelTemplate>
            <StackPanel Orientation="Horizontal" Background="Red"></StackPanel>
        </ItemsPanelTemplate>
    </Setter.Value>
</Setter>


<Setter Property="Template">
    <Setter.Value>
        <ControlTemplate TargetType="local:ChartLegend">
            <Border
                  BorderBrush="Black"
                  BorderThickness="5"
                  CornerRadius="{TemplateBinding CornerRadius}"
                  Padding="{TemplateBinding Padding}"
                  Background="Green" x:Name="SOI">
                <StackPanel Orientation="Vertical" VerticalAlignment="{TemplateBinding VerticalContentAlignment}" HorizontalAlignment="{TemplateBinding HorizontalContentAlignment}">
                    <ContentControl Content="{TemplateBinding Header}" ContentTemplate="{TemplateBinding HeaderTemplate}"/>
                    <ItemsPresenter/>
                </StackPanel>
            </Border>
        </ControlTemplate>
    </Setter.Value>
</Setter>

The ContentPresenter.Content has the width of the parent (a Canvas) and is not aligned properly.

Expected behavior

How to reproduce it (as minimally and precisely as possible)

cf. issue (private) linked below

==> Another repro which might be easier to investigate: #3755

Workaround

Manually align (usually Left) the control.

Environment

Nuget Package: Uno.UI
Package Version(s): 3.0
Affected platform(s):

• iOS
• Android
• WebAssembly
• WebAssembly renderers for Xamarin.Forms
• macOS
• Windows
• Build tasks
• Solution Templates

Visual Studio: irrelevant
Relevant plugins: none

Anything else we need to know?

This might have been fixed by https://github.com/unoplatform/uno/commits/dev/cdb/bugs/layout-bugs-big-refactoring (@carldebilly )

[ramezgerges]

A more minimal repro is

	<StackPanel x:Name="sp1">
	    <ContentControl x:Name="cc">
	        <StackPanel Width="240" x:Name="sp2">
	            <TextBox x:Name="tb" Text="textbox1" />
	        </StackPanel>
	    </ContentControl>
	</StackPanel>

The problem is not with StackPanel, but with ContentControl. On Android (and iOS, but I didn't test), we don't follow the WinUI template for ContentControl, which specifies Top and Left alignments for the inner ContentPresenter (by a TemplateBinding). Matching the template fixes the issues, but we left it that way as it caused other issues, so I guess this is blocked for now.

[Youssef1313]

I have #13069 but wasn't able to complete it.

[Youssef1313]

This will likely be fixed by #18261

[carldebilly]

This will likely be fixed by #18261

Old bug finally fixed :-) Great job.