feat: support paste.

src/Ursa/Controls/PinCode/PinCode.cs

@@ -159,8 +159,30 @@ public class PinCode: TemplatedControl
         };
     }
 
-    protected void OnPreviewKeyDown(KeyEventArgs e)
+    protected async void OnPreviewKeyDown(KeyEventArgs e)
     {
+        TextBox b = new TextBox();
+        var pasteKeys = Application.Current?.PlatformSettings.HotkeyConfiguration.Paste;
+        if (pasteKeys?.Any(a => a.Matches(e)) == true)
+        {
+            var clipboard = TopLevel.GetTopLevel(this)?.Clipboard;
+            var text = await clipboard.GetTextAsync();
+            if (text is not null)
+            {
+                var newText = text.Where(c => Valid(c, Mode)).Take(Count).ToArray();
+                for (int i = 0; i < newText.Length; i++)
+                {
+                    Digits[i] = newText[i].ToString();
+                    var presenter = _itemsControl?.ContainerFromIndex(i) as PinCodeItem;
+                    if (presenter is not null)
+                    {
+                        presenter.Focus();
+                        presenter.Text = newText[i].ToString();
+                    }
+                }
+            }
+            return;
+        }
         if (e.Key == Key.Tab && e.Source is PinCodeItem)
         {
             _currentIndex = MathHelpers.SafeClamp(_currentIndex, 0, Count - 1);

tests/HeadlessTest.Ursa/Controls/PinCodeTests/PasteTest.cs

@@ -0,0 +1,89 @@
+using Avalonia.Controls;
+using Avalonia.Headless;
+using Avalonia.Headless.XUnit;
+using Avalonia.Input;
+using Avalonia.Threading;
+using Ursa.Controls;
+
+namespace HeadlessTest.Ursa.Controls.PinCodeTests;
+
+public class PasteTest
+{
+    [AvaloniaFact]
+    public async void Paste_Should_Insert_Text()
+    {
+        var window = new Window();
+        var pinCode = new PinCode()
+        {
+            Count = 4,
+        };
+        window.Content = pinCode;
+        window.Show();
+        var clipboard = window.Clipboard;
+        Assert.NotNull(clipboard);
+        await clipboard.SetTextAsync("abcd");
+        pinCode.Focus();
+        window.KeyPressQwerty(PhysicalKey.V, RawInputModifiers.Control);
+        // add await for clipboard processing. 
+        await Task.Delay(1);
+        Assert.Equal("abcd", string.Join("", pinCode.Digits));
+    }
+    
+    [AvaloniaFact]
+    public async void Paste_Should_Insert_Text_When_Text_Is_Shorter()
+    {
+        var window = new Window();
+        var pinCode = new PinCode()
+        {
+            Count = 4,
+        };
+        window.Content = pinCode;
+        window.Show();
+        var clipboard = window.Clipboard;
+        Assert.NotNull(clipboard);
+        await clipboard.SetTextAsync("abc");
+        pinCode.Focus();
+        window.KeyPressQwerty(PhysicalKey.V, RawInputModifiers.Control);
+        await Task.Delay(1);
+        Assert.Equal("abc", string.Join("", pinCode.Digits));
+    }
+    
+    [AvaloniaFact]
+    public async void Paste_Should_Insert_Text_When_Text_Is_Longer()
+    {
+        var window = new Window();
+        var pinCode = new PinCode()
+        {
+            Count = 4,
+        };
+        window.Content = pinCode;
+        window.Show();
+        var clipboard = window.Clipboard;
+        Assert.NotNull(clipboard);
+        await clipboard.SetTextAsync("abcde");
+        pinCode.Focus();
+        window.KeyPressQwerty(PhysicalKey.V, RawInputModifiers.Control);
+        await Task.Delay(1);
+        Assert.Equal("abcd", string.Join("", pinCode.Digits));
+    }
+    
+    [AvaloniaFact]
+    public async void Paste_Should_Not_Insert_Text_When_Text_Is_In_Invalid_Mode()
+    {
+        var window = new Window();
+        var pinCode = new PinCode()
+        {
+            Count = 4,
+            Mode = PinCodeMode.Digit,
+        };
+        window.Content = pinCode;
+        window.Show();
+        var clipboard = window.Clipboard;
+        Assert.NotNull(clipboard);
+        await clipboard.SetTextAsync("abcde");
+        pinCode.Focus();
+        window.KeyPressQwerty(PhysicalKey.V, RawInputModifiers.Control);
+        await Task.Delay(1);
+        Assert.Equal("", string.Join("", pinCode.Digits));
+    }
+}