FlipView background not working on iOS

[ajpinedam]

Current behavior

Create a new Uno app and use this XAML code:

<StackPanel>
    <TextBlock Text="Text1" />
    <FlipView Width="500" Height="500" Background="Red" />
    <TextBlock Text="Text2" />
</StackPanel>

Expected behavior

No response

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

No response

Workaround

N/A

Works on UWP/WinUI

Yes

Environment

Uno.UI / Uno.UI.WebAssembly / Uno.UI.Skia, Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

No response

Affected platforms

Android

IDE

Visual Studio 2022

IDE version

17.6.4

Relevant plugins

No response

Anything else we need to know?

No response

[Youssef1313]

I tried a fix that didn't seem to work.

https://github.com/unoplatform/uno/pull/13204

[Xiaoy312]

var snapshot = await TakeScreenshot(parent);

var sample = parent.GetRelativeCoords(SUT);
var centerX = sample.X + sample.Width / 2;
var centerY = sample.Y + sample.Height / 2;

ImageAssert.HasPixels(
	snapshot,
	ExpectedPixels.At(centerX, centerY).Named("center with color").Pixel(Colors.Red));

there are two problems here:

1. the snapshot is in physical coords, while the sample are in logical coords which is affect android, but not ios
2. (probably specific to the templated-parent rework branch,) we are template-binding the Background property from the ItemsPanel to the FlipView crossing two templates (ControlTemplate + ItemsPanelTemplate):

   FlipView
   	ItemsPresenter // TemplatedParent=FlipView, Background=(well, is not set)
   		ContentControl // maybe present, for header
   		NativeFlipView // TemplatedParent=ItemsPresenter, Background={TemplateBinding Background}(ItemsPresenter doesnt have a Background set)
   		ContentControl // maybe present, for footer
   

   note that currently on master, NativeFlipView has FlipView for TP, so the binding could work.

[MartinZikmund]

No longer relevant for Skia targets, where it works correctly