How to change the FontFamily of MenuItem

[Rogersbin]

I want to use custom FontFamily in MenuItem. But it doesn't work at all.

<TextBox.ContextMenu>
                               <ContextMenu>
					<ContextMenu.Resources>
						<FontFamily x:Key="Source Han Sans SC Normal" >avares://X04/Assets/Fonts#Source Han Sans SC Normal</FontFamily>
					</ContextMenu.Resources>
					<MenuItem Header="Clear" FontFamily="{DynamicResource Source Han Sans SC Normal}"/>
				</ContextMenu>
</TextBox.ContextMenu>

And there is a similar issue in Button.
For example, it doesn't also work:

<Button Classes="accent" Content="Open" 
  Margin="10"
  FontFamily="StaticResource AR PL KaitiM Big5"/>

But it certainly works:

<Button Classes="accent"
					Margin="10">
				<TextBlock Text="Open" FontSize="16" FontFamily="{StaticResource AR PL KaitiM Big5}"/>
</Button>

It seems to only work in TextBlock for using FontFamily. Why?

Expected behavior

I want to know how to usefully use FontFamily in other Control but not only in TextBlock.

Desktop

• OS: Windows
• Version Windows 10 Home

[Rogersbin]

Fortunately，I find an useful solution.

• Add AppBuilderExtension.cs

using Avalonia.Media;

namespace X04.Desktop;

public static class AppBuilderExtension
{
    public static AppBuilder WithFontBySourceHanSansCN(this AppBuilder appBuilder)
    {
        var uri = "avares://Quick.AvaloniaFonts.SourceHanSansCN/Assets/Fonts#Source Han Sans CN";
        return appBuilder.With(new FontManagerOptions()
        {
            DefaultFamilyName = uri,
            FontFallbacks = new[] { new FontFallback { FontFamily = new FontFamily(uri) } }
        });
    }
}

• Then replace WithInterFont() with WithFontBySourceHanSansCN() in Program.cs.

using Avalonia;
using Avalonia.Media;
using Avalonia.ReactiveUI;
using System;

namespace X04.Desktop
{
    internal sealed class Program
    {
        // Initialization code. Don't use any Avalonia, third-party APIs or any
        // SynchronizationContext-reliant code before AppMain is called: things aren't initialized
        // yet and stuff might break.
        [STAThread]
        public static void Main(string[] args) => BuildAvaloniaApp()
            .StartWithClassicDesktopLifetime(args);

        // Avalonia configuration, don't remove; also used by visual designer.
        public static AppBuilder BuildAvaloniaApp()
            => AppBuilder.Configure<App>()
                .UsePlatformDetect()
                //.WithInterFont()
                .WithFontBySourceHanSansCN()
                .LogToTrace()
                .UseReactiveUI();
    }
}

Now run the app and it successfully works.

[jp2masa]

You can use TextElement.FontFamily. It works on TextBlock because the property is redefined there as AddOwner (source).

The available properties are these:

Avalonia/src/Avalonia.Controls/Documents/TextElement.cs

Lines 17 to 76 in e8c3bf5

	/// <summary>
	/// Defines the <see cref="FontFamily"/> property.
	/// </summary>
	public static readonly AttachedProperty<FontFamily> FontFamilyProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, FontFamily>(
	nameof(FontFamily),
	defaultValue: FontFamily.Default,
	inherits: true);
	/// <summary>
	/// Defines the <see cref="FontFeatures"/> property.
	/// </summary>
	public static readonly AttachedProperty<FontFeatureCollection?> FontFeaturesProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, FontFeatureCollection?>(
	nameof(FontFeatures),
	inherits: true);
	/// <summary>
	/// Defines the <see cref="FontSize"/> property.
	/// </summary>
	public static readonly AttachedProperty<double> FontSizeProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, double>(
	nameof(FontSize),
	defaultValue: 12,
	inherits: true);
	/// <summary>
	/// Defines the <see cref="FontStyle"/> property.
	/// </summary>
	public static readonly AttachedProperty<FontStyle> FontStyleProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, FontStyle>(
	nameof(FontStyle),
	inherits: true);
	/// <summary>
	/// Defines the <see cref="FontWeight"/> property.
	/// </summary>
	public static readonly AttachedProperty<FontWeight> FontWeightProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, FontWeight>(
	nameof(FontWeight),
	inherits: true,
	defaultValue: FontWeight.Normal);
	/// <summary>
	/// Defines the <see cref="FontStretch"/> property.
	/// </summary>
	public static readonly AttachedProperty<FontStretch> FontStretchProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, FontStretch>(
	nameof(FontStretch),
	inherits: true,
	defaultValue: FontStretch.Normal);
	/// <summary>
	/// Defines the <see cref="Foreground"/> property.
	/// </summary>
	public static readonly AttachedProperty<IBrush?> ForegroundProperty =
	AvaloniaProperty.RegisterAttached<TextElement, TextElement, IBrush?>(
	nameof(Foreground),
	Brushes.Black,
	inherits: true);

[Rogersbin]

But it also doesn't work when I use TextElement.FontFamily. For example,

<ContextMenu>
				<ContextMenu.Resources>
					<FontFamily x:Key="Source Han Sans SC Normal" >avares://X04/Assets/Fonts#Source Han Sans SC Normal</FontFamily>
				</ContextMenu.Resources>
				<MenuItem Header="Clear" TextElement.FontFamily="{DynamicResource Source Han Sans SC Normal}"
						  Command="{Binding ClearAllCommand}">
					
				</MenuItem>
</ContextMenu>

Can you enlighten me on this subject by giving some concrete proposals?

[timunie]

I'd try to remove the whitespaces from the x:Key as this can break things.