Support for AppThemeBindings

[HobDev]

Discussed in #75

^{Originally posted by HobDev June 23, 2022}
The docs have the SetAppThemeColor() and SetAppTheme(). This way I have to declare the colors on each UI element. There should be some better way to share style among the UI elements in C#. C# markup must support to declare the style once and use it throughout the app.

 static Color darkThemeTextColor = Color.FromArgb("#FFFFFF");
        static Color lightThemeTextColor = Color.FromArgb("#000000");

        static Style<Label> cSharpLabelStyle;
        public static Style<Label> CSharpLabelStyle => cSharpLabelStyle ?? (cSharpLabelStyle = new Style<Label>(
        (Label.TextColorProperty, new AppThemeBindingExtension { Dark = darkThemeTextColor, Light = lightThemeTextColor }),
        (Label.FontFamilyProperty, "OpenSansRegular"),
       (Label.FontSizeProperty, 14)
       ));

Finally use the style in UI :

new Label{Text = "Hello World" , HorizontalOptions=LayoutOptions.Center, VerticalOptions=LayoutOptions.Center}.Style(AppStyles.CSharpLabelStyle),

In the attached sample the color of the XAML Label changes with the change of mode. But the C# Label does not change color until the app restarts. Unable to check the change of device theme due to this bug.

MauiApp1.zip

[brminnick]

@HobDev It doesn't look like the Discussion in #75 is complete.

Please propose an API design and example of the new features usage in #75.

Once the feature has been fully fleshed out, you will open a New Feature Proposal.

For more information see the instructions for Submitting A New Feature in the README: https://github.com/CommunityToolkit/Maui.Markup#submitting-a-new-feature