feat: prototype.

demo/Ursa.Demo/Pages/BannerDemo.axaml

@@ -47,5 +47,6 @@
                 </Grid>
             </Border>
         </Grid>
+        <TextBox u:NumPad.Attach="True" Width="100" Watermark="Invoke NumPad"></TextBox>
     </StackPanel>
 </UserControl>

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

@@ -0,0 +1,14 @@
+<ResourceDictionary xmlns="https://github.com/avaloniaui"
+                    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+                    xmlns:u="https://irihi.tech/ursa">
+    <!-- Add Resources Here -->
+    <ControlTheme x:Key="{x:Type u:NumPad}" TargetType="{x:Type u:NumPad}">
+        <Setter Property="Template">
+            <ControlTemplate TargetType="u:NumPad">
+                <Border Padding="48">
+                    <Button Focusable="False" Name="{x:Static u:NumPad.PART_Seven}" Content="7" Width="32"></Button>
+                </Border>
+            </ControlTemplate>
+        </Setter>
+    </ControlTheme>
+</ResourceDictionary>

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

@@ -22,6 +22,7 @@
         <ResourceInclude Source="MessageBox.axaml" />
         <ResourceInclude Source="NavMenu.axaml" />
         <ResourceInclude Source="NumericUpDown.axaml" />
+        <ResourceInclude Source="NumPad.axaml" />
         <ResourceInclude Source="NumberDisplayer.axaml" />
         <ResourceInclude Source="Pagination.axaml" />
         <ResourceInclude Source="RangeSlider.axaml" />

src/Ursa/Controls/NumPad/NumPad.cs

@@ -0,0 +1,78 @@
+using Avalonia;
+using Avalonia.Controls;
+using Avalonia.Controls.Metadata;
+using Avalonia.Controls.Primitives;
+using Avalonia.Input;
+using Avalonia.Interactivity;
+using Irihi.Avalonia.Shared.Helpers;
+
+namespace Ursa.Controls;
+
+[TemplatePart(NumPad.PART_Seven, typeof(Button))]
+public class NumPad: TemplatedControl
+{
+    public const string PART_Seven = "PART_Seven";
+    private Button? _sevenButton;
+    public static readonly StyledProperty<InputElement?> TargetProperty = AvaloniaProperty.Register<NumPad, InputElement?>(
+        nameof(Target));
+
+    public InputElement? Target
+    {
+        get => GetValue(TargetProperty);
+        set => SetValue(TargetProperty, value);
+    }
+
+    public static readonly AttachedProperty<bool> AttachProperty =
+        AvaloniaProperty.RegisterAttached<NumPad, InputElement, bool>("Attach");
+
+    public static void SetAttach(InputElement obj, bool value) => obj.SetValue(AttachProperty, value);
+    public static bool GetAttach(InputElement obj) => obj.GetValue(AttachProperty);
+
+    static NumPad()
+    {
+        TargetProperty.Changed.AddClassHandler<NumPad, InputElement?>((n, args) => n.OnTargetChanged(args));
+        AttachProperty.Changed.AddClassHandler<InputElement, bool>((input, args)=> OnAttachNumPad(input, args));
+    }
+
+    private static void OnAttachNumPad(InputElement input, AvaloniaPropertyChangedEventArgs<bool> args)
+    {
+        if (args.NewValue.Value)
+        {
+            GotFocusEvent.AddHandler(OnTargetGotFocus, input);
+        }
+        else
+        {
+            GotFocusEvent.RemoveHandler(OnTargetGotFocus, input);
+        }
+    }
+
+    private void OnTargetChanged(AvaloniaPropertyChangedEventArgs<InputElement?> args)
+    {
+        //GotFocusEvent.RemoveHandler(OnTargetGotFocus, args.OldValue.Value);
+        //GotFocusEvent.AddHandler(OnTargetGotFocus, args.NewValue.Value);
+    }
+    
+    private static void OnTargetGotFocus(object sender, GotFocusEventArgs e)
+    {
+        var numPad = new NumPad() { Target = sender as InputElement };
+        OverlayDialog.ShowCustom(numPad, new object());
+    }
+
+    protected override void OnApplyTemplate(TemplateAppliedEventArgs e)
+    {
+        base.OnApplyTemplate(e);
+        Button.ClickEvent.RemoveHandler(OnSevenButtonClick, _sevenButton);
+        _sevenButton = e.NameScope.Find<Button>(PART_Seven);
+        Button.ClickEvent.AddHandler(OnSevenButtonClick, _sevenButton);
+    }
+
+    private void OnSevenButtonClick(object sender, RoutedEventArgs e)
+    {
+        Target?.RaiseEvent(new TextInputEventArgs()
+        {
+            Source = this,
+            RoutedEvent = TextInputEvent,
+            Text = "7",
+        });
+    }
+}