[Android] Allow to use system fonts

[jsuarezruiz]

Description of Change

Allow to use Android system fonts directly.

<VerticalStackLayout VerticalOptions="Center">
    <Label
        Text="Hello world" />
    <Label
        FontFamily="monospace"
        Text="Hello world" />
    <Label
        FontFamily="serif"
        Text="Hello world" />
</VerticalStackLayout>

Issues Fixed

Fixes #11422

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[jonathanpeppers]

@jsuarezruiz these changes cause an exception to be thrown several times on startup in an app I've been testing:

06-19 15:31:19.834  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium' from assets.
06-19 15:31:19.840  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium.ttf' from assets.
06-19 15:31:19.840  5706  5706 I DOTNET  : Unable to load font 'Fonts/sans-serif-medium.ttf' from assets.
06-19 15:31:19.841  5706  5706 I DOTNET  : Unable to load font 'fonts/sans-serif-medium.ttf' from assets.
06-19 15:31:19.841  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium.otf' from assets.
06-19 15:31:19.842  5706  5706 I DOTNET  : Unable to load font 'Fonts/sans-serif-medium.otf' from assets.
06-19 15:31:19.842  5706  5706 I DOTNET  : Unable to load font 'fonts/sans-serif-medium.otf' from assets.

maui/src/Core/src/Fonts/FontManager.Android.cs

Lines 127 to 128 in 503b534

	if (warning)
	_serviceProvider?.CreateLogger<FontManager>()?.LogWarning(ex, "Unable to load font '{Font}' from assets.", fontfamily);

(NOTE: I changed the above to Console.WriteLine() and fixed the missing $ locally)

On a Pixel 5, dotnet-trace shows a decent amount of time doing this:

64.98ms microsoft.maui!Microsoft.Maui.Handlers.LabelHandler.MapFont(Microsoft.Maui.Handlers.ILabelHandler,Microsoft.Maui.ILabel)
38.92ms microsoft.maui!Microsoft.Maui.FontManager.LoadTypefaceFromAsset(string,bool)

I open the Shell flyout in this app to see these:

https://github.com/supershopping/ShellFlyoutLagging

Is there something going wrong here?

[jsuarezruiz]

@jsuarezruiz these changes cause an exception to be thrown several times on startup in an app I've been testing:

06-19 15:31:19.834  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium' from assets.
06-19 15:31:19.840  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium.ttf' from assets.
06-19 15:31:19.840  5706  5706 I DOTNET  : Unable to load font 'Fonts/sans-serif-medium.ttf' from assets.
06-19 15:31:19.841  5706  5706 I DOTNET  : Unable to load font 'fonts/sans-serif-medium.ttf' from assets.
06-19 15:31:19.841  5706  5706 I DOTNET  : Unable to load font 'sans-serif-medium.otf' from assets.
06-19 15:31:19.842  5706  5706 I DOTNET  : Unable to load font 'Fonts/sans-serif-medium.otf' from assets.
06-19 15:31:19.842  5706  5706 I DOTNET  : Unable to load font 'fonts/sans-serif-medium.otf' from assets.

maui/src/Core/src/Fonts/FontManager.Android.cs

Lines 127 to 128 in 503b534

	if (warning)
	_serviceProvider?.CreateLogger<FontManager>()?.LogWarning(ex, "Unable to load font '{Font}' from assets.", fontfamily);

(NOTE: I changed the above to Console.WriteLine() and fixed the missing $ locally)

On a Pixel 5, dotnet-trace shows a decent amount of time doing this:

64.98ms microsoft.maui!Microsoft.Maui.Handlers.LabelHandler.MapFont(Microsoft.Maui.Handlers.ILabelHandler,Microsoft.Maui.ILabel)
38.92ms microsoft.maui!Microsoft.Maui.FontManager.LoadTypefaceFromAsset(string,bool)

I open the Shell flyout in this app to see these:

https://github.com/supershopping/ShellFlyoutLagging

Is there something going wrong here?

I think you found this one: #13239
Searching the possible origin, could be:

https://github.com/dotnet/maui/blob/main/src/Controls/src/Core/Platform/Android/BottomNavigationViewUtils.cs#L218
https://github.com/dotnet/maui/blob/main/src/Controls/src/Core/Compatibility/Handlers/Shell/Android/ShellItemRenderer.cs#L248

[jonathanpeppers]

Ok, I think we should add a couple more cases: #15759

It seems to help performance to avoid these lookups.