[Package Size] Reduce size of new Controls.Primitives Package

[michael-hawker]

Describe the problem this feature would solve

I noticed from the report in #3676 that the Primitives package is still fairly large if you just want the panels and nothing else from the toolkit:

Microsoft.Toolkit.Uwp.UI.Controls.Primitives Additional Footprint: 486,329 bytes
  App Diff: (.exe) = 3,072
  App Diff: (.xml) = 657
  App Diff: (.appxsym) = 90,372
  Size Diff: AppxBundleManifest.xml = 34
  Size Diff: AppxBlockMap.xml = 961
  Size Diff: AppxManifest.xml = 33
  Size Diff: resources.pri = 544
  Size Diff: System.Runtime.CompilerServices.Unsafe.dll = 1,536
  Additional: Microsoft.Toolkit.dll = 96,768
  Additional: Microsoft.Toolkit.Uwp.dll = 104,448
  Lib (self): Microsoft.Toolkit.Uwp.UI.Controls.Primitives.dll = 42,496
  Additional: Microsoft.Toolkit.Uwp.UI.dll = 145,408
-----------------------------------------

I did a quick investigation, and I think the only place an element from a lower package is used is in the DockPanel for FindParent here:

https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/542498998d218efe942c566529d4da5631b1994b/Microsoft.Toolkit.Uwp.UI.Controls/DockPanel/DockPanel.cs#L18-L24

If we were able to remove this reference we could say the Primitives package has no other dependencies and effectively shrink the package:

Microsoft.Toolkit.Uwp.UI.Controls.Primitives Additional Footprint: ~>139,705 bytes
  App Diff: (.exe) = 3,072
  App Diff: (.xml) = 657
  App Diff: (.appxsym) = 90,372
  Size Diff: AppxBundleManifest.xml = 34
  Size Diff: AppxBlockMap.xml = 961
  Size Diff: AppxManifest.xml = 33
  Size Diff: resources.pri = 544
  Size Diff: System.Runtime.CompilerServices.Unsafe.dll = 1,536
  Lib (self): Microsoft.Toolkit.Uwp.UI.Controls.Primitives.dll = 42,496
-----------------------------------------

There's also a small reference to the guard API in the UniformGrid internal helper which we could remove?

This would help support #3145 of course too.

Describe the solution

Evaluate removing the extra dependency to make the the Primitives package super light-weight in case no other elements of the Toolkit wish to be used by the end developer.

@vgromfeld @Sergio0694 @skendrot @RosarioPulella thoughts?

[michael-hawker]

@RosarioPulella forgot to ask if you noticed any other opportunities like this elsewhere in any of the refactors?

[Rosuavio]

If we were able to remove this reference we could say the Primitives package has no other dependencies and effectively shrink the package

From Microsoft.Toolkit Primitives

uses Guards twice
https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/f55f101ca2be0772e02190c045b805d64501cf8a/Microsoft.Toolkit.Uwp.UI.Controls.Primitives/UniformGrid/TakenSpotsReferenceHolder.cs#L31
https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/f55f101ca2be0772e02190c045b805d64501cf8a/Microsoft.Toolkit.Uwp.UI.Controls.Primitives/UniformGrid/TakenSpotsReferenceHolder.cs#L32

And ThrowHelper once
https://github.com/windows-toolkit/WindowsCommunityToolkit/blob/f55f101ca2be0772e02190c045b805d64501cf8a/Microsoft.Toolkit.Uwp.UI.Controls.Primitives/WrapPanel/WrapPanel.Data.cs#L66

If we replaced FindParent we can drop Microsoft.Toolkit.Uwp and Microsoft.Toolkit.Uwp.UI but Microsoft.Toolkit would require replacing our usage of Guards and ThrowHelper.

[michael-hawker]

@RosarioPulella looking at some of the initial impact reports Microsoft.Toolkit is definitely lighter than Microsoft.Toolkit.Uwp.UI for sure. I'm curious if we could get around the need for the FindParent usage in DockPanel somehow entirely (vs. copying that method).

Let me see how the rest of my investigation goes.

[michael-hawker]

Think we're good here for now, just going to close this.