feat: inherit font properties.

demo/Ursa.Demo/Pages/NumberDisplayerDemo.axaml

@@ -1,17 +1,23 @@
-<UserControl xmlns="https://github.com/avaloniaui"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
-             xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
-             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
-             xmlns:u="https://irihi.tech/ursa"
-             xmlns:vm="using:Ursa.Demo.ViewModels"
-             x:DataType="vm:NumberDisplayerDemoViewModel"
-             x:CompileBindings="True"
-             mc:Ignorable="d" d:DesignWidth="800" d:DesignHeight="450"
-             x:Class="Ursa.Demo.Pages.NumberDisplayerDemo">
+<UserControl
+    x:Class="Ursa.Demo.Pages.NumberDisplayerDemo"
+    xmlns="https://github.com/avaloniaui"
+    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
+    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
+    xmlns:u="https://irihi.tech/ursa"
+    xmlns:vm="using:Ursa.Demo.ViewModels"
+    d:DesignHeight="450"
+    d:DesignWidth="800"
+    x:CompileBindings="True"
+    x:DataType="vm:NumberDisplayerDemoViewModel"
+    mc:Ignorable="d">
     <StackPanel HorizontalAlignment="Left">
-        <Button Command="{Binding IncreaseCommand}" >Change</Button>
-        <u:Int32Displayer Value="{Binding Value}"></u:Int32Displayer>
-        <u:DoubleDisplayer Value="{Binding DoubleValue}" StringFormat="N2"></u:DoubleDisplayer>
-        <u:DateDisplay Value="{Binding DateValue}" StringFormat="yyyy-MM-dd"></u:DateDisplay>
+        <Button Command="{Binding IncreaseCommand}">Change</Button>
+        <u:Int32Displayer Value="{Binding Value}" />
+        <u:DoubleDisplayer StringFormat="N2" Value="{Binding DoubleValue}" />
+        <u:DateDisplay
+            FontSize="30"
+            StringFormat="yyyy-MM-dd"
+            Value="{Binding DateValue}" />
     </StackPanel>
 </UserControl>

src/Ursa.Themes.Semi/Controls/NumberDisplayer.axaml

@@ -8,7 +8,16 @@
         <Setter Property="Duration" Value="0:0:0.2" />
         <Setter Property="Template">
             <ControlTemplate TargetType="u:NumberDisplayerBase">
-                <TextBlock Text="{TemplateBinding InternalText, Mode=OneWay}" />
+                <TextBlock
+                    FontSize="{TemplateBinding FontSize}"
+                    Foreground="{TemplateBinding Foreground}"
+                    FontFamily="{TemplateBinding FontFamily}"
+                    Background="{TemplateBinding Background}"
+                    FontWeight="{TemplateBinding FontWeight}"
+                    FontStyle="{TemplateBinding FontSize}"
+                    FontStretch="{TemplateBinding FontStretch}"
+                    Text="{TemplateBinding InternalText,
+                                           Mode=OneWay}" />
             </ControlTemplate>
         </Setter>
     </ControlTheme>

src/Ursa/Controls/NumberDisplayer/NumberDisplayer.cs

@@ -1,8 +1,10 @@
 using Avalonia;
 using Avalonia.Animation;
 using Avalonia.Controls;
+using Avalonia.Controls.Documents;
 using Avalonia.Controls.Primitives;
 using Avalonia.Data;
+using Avalonia.Media;
 using Avalonia.Styling;
 
 namespace Ursa.Controls;
@@ -13,7 +15,7 @@ public abstract class NumberDisplayerBase : TemplatedControl
         nameof(InternalText), o => o.InternalText, (o, v) => o.InternalText = v);
     private string _internalText;
     
-    public string InternalText
+    internal string InternalText
     {
         get => _internalText;
         set => SetAndRaise(InternalTextProperty, ref _internalText, value);
@@ -51,11 +53,11 @@ public abstract class NumberDisplayer<T>: NumberDisplayerBase
         get => GetValue(ValueProperty);
         set => SetValue(ValueProperty, value);
     }
-    
-    public static readonly StyledProperty<T?> InternalValueProperty = AvaloniaProperty.Register<NumberDisplayer<T>, T?>(
-        nameof(InternalValue));
 
-    public T? InternalValue
+    private static readonly StyledProperty<T?> InternalValueProperty = AvaloniaProperty.Register<NumberDisplayer<T>, T?>(
+        nameof(InternalValue), defaultBindingMode:BindingMode.TwoWay);
+
+    private T? InternalValue
     {
         get => GetValue(InternalValueProperty);
         set => SetValue(InternalValueProperty, value);
@@ -73,13 +75,15 @@ public abstract class NumberDisplayer<T>: NumberDisplayerBase
         });
         DurationProperty.Changed.AddClassHandler<NumberDisplayer<T>, TimeSpan>((item, args) =>item.OnDurationChanged(args));
     }
-
-    protected override void OnInitialized()
+    
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
     {
-        base.OnInitialized();
-        _animation = new Animation();
-        _animation.Duration = Duration;
-        _animation.FillMode = FillMode.Forward;
+        base.OnApplyTemplate(e);
+        _animation = new Animation
+        {
+            Duration = Duration,
+            FillMode = FillMode.Forward
+        };
         _animation.Children.Add(new KeyFrame()
         {
             Cue = new Cue(0.0),
@@ -92,7 +96,9 @@ public abstract class NumberDisplayer<T>: NumberDisplayerBase
         });
         Animation.SetAnimator(_animation.Children[0].Setters[0], GetAnimator());
         Animation.SetAnimator(_animation.Children[1].Setters[0], GetAnimator());
-        InternalValue = Value;
+        
+        // Display value directly to text on initialization in case value equals to default. 
+        SetCurrentValue(InternalTextProperty, this.GetString(Value));
     }
 
     private void OnDurationChanged(AvaloniaPropertyChangedEventArgs<TimeSpan> args)
@@ -101,9 +107,13 @@ public abstract class NumberDisplayer<T>: NumberDisplayerBase
         _animation.Duration = args.NewValue.Value;
     }
 
-    protected virtual void OnValueChanged(T? oldValue, T? newValue)
+    private void OnValueChanged(T? oldValue, T? newValue)
     {
-        if (_animation is null) return;
+        if (_animation is null)
+        {
+            SetCurrentValue(InternalValueProperty, newValue);
+            return;
+        }
         _cts.Cancel();
         _cts = new CancellationTokenSource();
         (_animation.Children[0].Setters[0] as Setter)!.Value = oldValue;
@@ -119,7 +129,6 @@ public abstract class NumberDisplayer<T>: NumberDisplayerBase
 public class Int32Displayer : NumberDisplayer<int>
 {
     protected override Type StyleKeyOverride { get; } = typeof(NumberDisplayerBase);
-    
 
     protected override InterpolatingAnimator<int> GetAnimator()
     {
@@ -176,7 +185,8 @@ public class DateDisplay : NumberDisplayer<DateTime>
     {
         public override DateTime Interpolate(double progress, DateTime oldValue, DateTime newValue)
         {
-            return oldValue + TimeSpan.FromTicks((long)((newValue - oldValue).Ticks * progress));
+            var diff = (newValue - oldValue).TotalSeconds;
+            return oldValue + TimeSpan.FromSeconds(diff * progress);
         }
     }