[wasm] FlipView does not increase SelectedIndex when swiping on mobile devices

[ryanwin98]

Current behavior

When using swipe controls to go between items in the FlipView the SelectedIndex does not update. This causes issues such as the PipsPager not updating correctly

Expected behavior

The SelectedIndex should update when swiping between items in the FlipView

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

https://github.com/unoplatform/uno/assets/104783204/9ff91e71-0b36-4cc0-8794-0c8cfea4d70b

1. Launch an application with FlipView on wasm
2. In the browser dev tools, select device emulation
3. Use the swipe controls to go through items in the FlipView

Workaround

N/A

Works on UWP/WinUI

None

Environment

Uno.WinUI / Uno.WinUI.WebAssembly / Uno.WinUI.Skia

NuGet package version(s)

5.1.0-dev.1377

Affected platforms

WebAssembly

IDE

Visual Studio 2022

IDE version

17.8.5

Relevant plugins

No response

Anything else we need to know?

No response

[Youssef1313]

This could be a regression from https://github.com/unoplatform/uno/pull/14491

[jeromelaban]

@ryanwin98 can you validate if this is a regression by checking if some of the early Uno 5.0 builds have this issue?

[ryanwin98]

@jeromelaban rolled by to some earlier version of 5.1 and still viewed this bug, currently downgrading the project to see it the issue still exists in 5.0

[ryanwin98]

@jeromelaban downgraded to 5.0.19 and i was still facing the same issue

[jeromelaban]

Thanks. Have you also tried the latest builds of 5.2-dev? It may show differences.

[ryanwin98]

@jeromelaban upgraded to 5.2.0-dev.426 and the issue is still present

[Youssef1313]

This is a regression from https://github.com/unoplatform/uno/pull/14491

[Youssef1313]

The original root cause for #14488 is wrong IsIntermediate value (we hardcode it to false):

https://github.com/unoplatform/uno/blob/f632b08e8d980326001d3b5da7a64c72a8ee8dd5/src/Uno.UI/UI/Xaml/Controls/ScrollContentPresenter/ScrollContentPresenter.wasm.cs#L345-L354