Fix virtual key to char conversion on Windows (#26)

* Add key char to sample app

* Fix virtual key to char conversion on Windows

Fixes: #25

* addressing some copilot feedback

---------

Co-authored-by: David Ortinau <david.ortinau@microsoft.com>

Author: jeremy-visionaid

samples/Plugin.Maui.KeyListener.Sample/MainPage.xaml.cs

@@ -21,10 +21,10 @@ void AddKeyboardBehavior()
 
 	void PrependOutput(string eventName, KeyPressedEventArgs e)
 	{
-		OutputLabel.Text = $"{eventName}: {e.Modifiers} {e.Keys}" + Environment.NewLine + OutputLabel.Text;
+		OutputLabel.Text = $"{eventName}: {e.Modifiers} {e.Keys} {e.KeyChar}" + Environment.NewLine + OutputLabel.Text;
 	}
 
-	private void ClearButton_Clicked(object sender, EventArgs e)
+	void ClearButton_Clicked(object sender, EventArgs e)
 	{
 		OutputLabel.Text = string.Empty;
 	}

src/Plugin.Maui.KeyListener/KeyboardBehavior.Windows.cs

@@ -49,13 +49,7 @@ void OnWindowKeyDown(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs e
 
 	void OnKeyDown(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs e)
 	{
-		char keyChar = ((char)e.Key);
-		var eventArgs = new KeyPressedEventArgs
-		{
-			Keys = e.Key.ToKeyboardKeys(),
-			KeyChar = keyChar
-		};
-
+		var eventArgs = e.ToKeyPressedEventArgs();
 		this.RaiseKeyDown(eventArgs);
 	}
 	void OnPreviewKeyUp(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs e)
@@ -70,12 +64,7 @@ void OnPreviewKeyDown(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs
 
 	void OnKeyUp(object sender, Microsoft.UI.Xaml.Input.KeyRoutedEventArgs e)
 	{
-		char keyChar = ((char)e.Key);
-		var eventArgs = new KeyPressedEventArgs
-		{
-			Keys = e.Key.ToKeyboardKeys(),
-			KeyChar = keyChar
-		};
+		var eventArgs = e.ToKeyPressedEventArgs();
 		this.RaiseKeyUp(eventArgs);
 	}
 }

src/Plugin.Maui.KeyListener/KeyboardKeysExtensions.Windows.cs

@@ -1,6 +1,8 @@
 #if WINDOWS
 
+using Microsoft.UI.Xaml.Input;
 using Windows.System;
+using Windows.Win32.UI.Input.KeyboardAndMouse;
 
 namespace Plugin.Maui.KeyListener;
 
@@ -163,5 +165,16 @@ internal static partial class KeyboardKeysExtensions
 		VirtualKey.NumberPad9 => KeyboardKeys.NumPad9,
 		_ => 0
 	};
+
+	public static char ToChar(this VirtualKey key) => (char)Windows.Win32.PInvoke.MapVirtualKey((uint)key, MAP_VIRTUAL_KEY_TYPE.MAPVK_VK_TO_CHAR);
+
+	internal static KeyPressedEventArgs ToKeyPressedEventArgs(this KeyRoutedEventArgs e)
+	{
+		return new KeyPressedEventArgs
+		{
+			Keys = e.Key.ToKeyboardKeys(),
+			KeyChar = e.Key.ToChar(),
+		};
+	}
 }
 #endif

src/Plugin.Maui.KeyListener/NativeMethods.json

@@ -0,0 +1,6 @@
+{
+  "$schema": "https://aka.ms/CsWin32.schema.json",
+  "wideCharOnly": true,
+  "emitSingleFile": true,
+  "public": false
+}

src/Plugin.Maui.KeyListener/NativeMethods.txt

@@ -0,0 +1 @@
+MapVirtualKey

src/Plugin.Maui.KeyListener/Plugin.Maui.KeyListener.csproj

@@ -72,6 +72,10 @@
 
 	<ItemGroup>
 		<PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="all" IsImplicitlyDefined="true" />
+		<PackageReference Include="Microsoft.Windows.CsWin32" Version="0.3.183" Condition="$(TargetFramework.StartsWith('net')) == true AND $(TargetFramework.Contains('-windows')) == true">
+		  <PrivateAssets>all</PrivateAssets>
+		  <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+		</PackageReference>
 	</ItemGroup>
 
 	<!-- Package additions -->