[Windows] Skip initial assignments in property mapper (take 3)

[MartyIX]

Description of Change

Alternative to #22108

Performance implications

• MAIN: 1722625589..speedscope.json
• PR: 1722625386..speedscope.PR.InitAssignments.json

Best time observed

• In April, the time was about 900 ms.
• In May/June, then time was about 300-400ms.
• I believe that [Windows] Handle focus events using FocusManager (take 2) #24695 helped us to get to ~200ms.

BTW: In vanilla WinUI, the grid scenario takes ~100 ms. So MAUI is only about 50% slower than WinUI with this PR.

Issues Fixed

Contributes to #17303
Contributes to #21787

[MartyIX]

This is the main change.

I placed the property in ElementHandler because then it's not a public API change.

[mattleibow]

Maybe this can be an internal property:

Suggested change

	internal bool _isPlatformViewNew;
	internal bool IsPlatformViewInitialized { get; }

But in a perfect world, where would this property go? Should this be on an interface or something to avoid the cast in each mapper? Pity we never added a isFirstRun property to the mappers... pity.

But maybe we just need a handler IsInitialized property to IElementHandler? Can we add that as a default interface implementation?

[MartyIX]

Maybe this can be an internal property:

If you mean this:

private bool _isPlatformViewInitialized; // we can read & write
internal bool IsPlatformViewInitialized => _isPlatformViewInitialized; // not writable from outside

Yes. That should be possible.

But in a perfect world, where would this property go? Should this be on an interface or something to avoid the cast in each mapper? Pity we never added a isFirstRun property to the mappers... pity.

I think that in a perfect world, it would be passed through mappers. But unfortunately, I don't see a way to do it there.

But maybe we just need a handler IsInitialized property to IElementHandler? Can we add that as a default interface implementation?

If you mean this https://github.com/MartyIX/maui/tree/feature/2024-09-13-IsInitialized (MartyIX@bff5ee4), then it requires an API change and there would be many additional changes needed - see:

That is because .NET Standard 2.0 does not support default interface implementations (flashback).

[PureWeen]

/azp run

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