[Skia] ScrollViewer.ViewChanged is fired before content is scrolled (i.e. with outdated offsets)

[ramezgerges]

Current behavior

Related to https://github.com/unoplatform/uno-private/issues/1291

Due to the way ScrollViewer scrolling currently wortks (with composition animations), we start the scrolling animation and fire ViewChanged before the animation has ended, leading to any offset values read on the Visual of the content of the ScrollViewer to be outdated, most notably when calling TransformToVisual on the content of the ScrollViewer.

Expected behavior

No response

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

No response

Workaround

No response

Works on UWP/WinUI

None

Environment

No response

NuGet package version(s)

No response

Renderer

• [ ] Skia
• [ ] Native

Affected platforms

No response

IDE

No response

IDE version

No response

Relevant plugins

No response

Anything else we need to know?

No response

[ramezgerges]

cc. @dr1rrb @jeromelaban

[dr1rrb]

If it's about the composition animation, then it will impact:

1. Mouse wheel scrolling
2. Programmatic ChangeView

The second doesn't seems really problematic IMO, but the first is quite important. The good point is that we have better control on it :)

[dr1rrb]

Actually this has probably a major impact on the ItemsRepeater when fast scrolling mouse-wheel!

[HakanL]

Could this be related to this https://github.com/unoplatform/uno/issues/20637?

[jhanvi03]

The issue occurs on HD as well

[Jen-Uno]

@ajpinedam what is the status on this issue, please?

[ajpinedam]

@Jen-Uno Pushed draft PR with the fix. Working on the RuntimeTests.

[khaskoul]

Issue is fixed Tested with: Templates/SDK: 6.2.7 Platform(s): Desktop, Wasm IDE: VS 2022 - 17.14.9 OS: Windows