[.NET 11] Migrate off internal MAUI APIs before InternalsVisibleTo removal

[jfversluis]

Summary

In .NET 11, InternalsVisibleTo for the .NET MAUI Community Toolkit will be removed from all MAUI assemblies (see dotnet/maui#34070).

This was attempted twice before for .NET 10 (dotnet/maui#28994, dotnet/maui#33442) but had to be reverted both times because the toolkit hadn't migrated off internal APIs yet.

This issue tracks the toolkit-side work needed to complete the migration.

Internal APIs That Can Be Fixed Now (Public Alternatives Exist)

These can be addressed on the toolkit side without any MAUI changes:

API	Toolkit Usage	Migration Path
InvalidateMeasureInternal(InvalidationTrigger)	AvatarView.shared.cs (2 call sites)	Replace with public InvalidateMeasure()
XamlParseException(string, IServiceProvider)	AppThemeResourceExtension.shared.cs (5 call sites)	Switch to public ctor XamlParseException(string, IXmlLineInfo)
GetDefaultFontSize()	AvatarView.shared.cs (1 call site)	Resolve IFontManager.DefaultFontSize from Handler.MauiContext.Services
RequireFontManager()	Snackbar.android.cs, UIFontExtensions.macios.cs	Resolve IFontManager from MauiContext.Services.GetRequiredService<IFontManager>()
AppThemeBinding	AppThemeObject.shared.cs (1 call site)	Already public on net11.0 — no change needed
GetTargetOrDefault()	Snackbar.shared.cs	Already self-solved — toolkit has own copy in WeakReferenceExtensions.cs

Internal APIs That Require MAUI to Provide Public Alternatives

These are blocked until MAUI makes them public (tracked in dotnet/maui#34070):

API	Toolkit Usage	Affected Controls
FontElement (static class)	FontAttributesProperty, FontAutoScalingEnabledProperty, FontFamilyProperty, FontSizeProperty	AvatarView
TextElement (static class)	TextColorProperty, TextTransformProperty, CharacterSpacingProperty	AvatarView
ImageElement (static class)	SourceProperty, AspectProperty	AvatarView, TouchBehavior, ImageTouchBehavior
IResourcesProvider (interface)	Pattern match on IsResourcesCreated	AppThemeResourceExtension
ImageSource.CancellationTokenSource	private protected property access	GravatarImageSource
StreamWrapper	StreamWrapper.GetStreamAsync()	HttpClientExtensions (used by GravatarImageSource)

Affected Toolkit Controls/Features

Control	Internal APIs Used	Can Fix Now?
AvatarView	FontElement, TextElement, ImageElement, GetDefaultFontSize(), InvalidateMeasureInternal()	Partially
AppThemeObject	AppThemeBinding	✅ Yes (public in .NET 11)
AppThemeResourceExtension	IResourcesProvider, XamlParseException internal ctor	Partially
GravatarImageSource	ImageSource.CancellationTokenSource, StreamWrapper	❌ Blocked on MAUI
Snackbar	RequireFontManager()	✅ Yes
TouchBehavior / ImageTouchBehavior	ImageElement	❌ Blocked on MAUI
UIFont extensions	RequireFontManager()	✅ Yes

Suggested Approach

1. Immediately: Migrate the 6 APIs that have public alternatives (listed above)
2. When MAUI provides public types: Migrate FontElement, TextElement, ImageElement, IResourcesProvider, ImageSource.CancellationTokenSource, StreamWrapper
3. For StreamWrapper: Consider rewriting HttpClientExtensions to use HttpClient directly instead of depending on MAUI's internal wrapper

Related Issues & PRs

• dotnet/maui#34070 — Remove IVT for .NET 11
• dotnet/maui#34048 — Original breakage report
• dotnet/maui#29444 — Tracking issue for IVT removal
• dotnet/maui#29443 — First batch of types made public
• [NET10] Switch to public MAUI types for AvatarView #2646 — Previous tracking issue (closed)

cc @TheCodeTraveler @jfversluis

[TheCodeTraveler]

Thanks Gerald!

What's the plan for CommunityToolkit.Maui.Markup? These are the APIs it needs:

• sealed class BindingExpression
• internal readonly struct SetterSpecificity
• internal sealed class WeakPropertyChangedProxy
• The internal constructor for TypedBindingBase:
  • internal TypedBindingBase()

I've documented the Internal APIs we're using across the Toolkits here in this Issue:
dotnet/maui#34048 (comment)