Implement CharacterSpacing property in EditorHandlers (#516)

src/Compatibility/Core/src/Android/Renderers/EditorRenderer.cs

@@ -243,6 +243,7 @@ void UpdateInputType()
 			}
 		}
 
+		[PortHandler]
 		void UpdateCharacterSpacing()
 		{
 			if (Forms.IsLollipopOrNewer)

src/Compatibility/Core/src/iOS/Renderers/EditorRenderer.cs

@@ -70,6 +70,7 @@ protected internal override void UpdatePlaceholderText()
 			_placeholderLabel.SizeToFit();
 		}
 
+		[PortHandler("Partially ported")]
 		protected internal override void UpdateCharacterSpacing()
 		{
 			var textAttr = TextView.AttributedText.AddCharacterSpacing(Element.Text, Element.CharacterSpacing);

src/Core/src/Handlers/Editor/EditorHandler.Android.cs

@@ -25,5 +25,10 @@ public static void MapText(EditorHandler handler, IEditor editor)
 		{
 			handler.TypedNativeView?.UpdateText(editor);
 		}
+
+		public static void MapCharacterSpacing(EditorHandler handler, IEditor editor)
+		{
+			handler.TypedNativeView?.UpdateCharacterSpacing(editor);
+		}
 	}
 }

src/Core/src/Handlers/Editor/EditorHandler.Standard.cs

@@ -7,5 +7,6 @@ public partial class EditorHandler : AbstractViewHandler<IEditor, object>
 		protected override object CreateNativeView() => throw new NotImplementedException();
 
 		public static void MapText(IViewHandler handler, IEditor editor) { }
+		public static void MapCharacterSpacing(IViewHandler handler, IEditor editor) { }
 	}
 }

src/Core/src/Handlers/Editor/EditorHandler.cs

@@ -4,7 +4,8 @@ public partial class EditorHandler
 	{
 		public static PropertyMapper<IEditor, EditorHandler> EditorMapper = new PropertyMapper<IEditor, EditorHandler>(ViewHandler.ViewMapper)
 		{
-			[nameof(IEditor.Text)] = MapText
+			[nameof(IEditor.Text)] = MapText,
+			[nameof(IEditor.CharacterSpacing)] = MapCharacterSpacing
 		};
 
 		public EditorHandler() : base(EditorMapper)

src/Core/src/Handlers/Editor/EditorHandler.iOS.cs

@@ -19,5 +19,10 @@ public static void MapText(EditorHandler handler, IEditor editor)
 		{
 			handler.TypedNativeView?.UpdateText(editor);
 		}
+
+		public static void MapCharacterSpacing(EditorHandler handler, IEditor editor)
+		{
+			handler.TypedNativeView?.UpdateCharacterSpacing(editor);
+		}
 	}
 }

src/Core/src/Platform/Android/EditorExtensions.cs

@@ -18,5 +18,10 @@ public static void UpdateText(this AppCompatEditText editText, IEditor editor)
 
 			editText.SetSelection(text.Length);
 		}
+
+		public static void UpdateCharacterSpacing(this AppCompatEditText editText, IEditor editor)
+		{
+			editText.LetterSpacing = editor.CharacterSpacing.ToEm();
+		}
 	}
 }

src/Core/src/Platform/iOS/CharacterSpacingExtensions.cs

@@ -0,0 +1,62 @@
+using Foundation;
+using UIKit;
+
+namespace Microsoft.Maui
+{
+	public static class CharacterSpacingExtensions
+	{
+		public static NSMutableAttributedString? AddCharacterSpacing(this NSAttributedString attributedString, string text, double characterSpacing)
+		{
+			if (attributedString == null && characterSpacing == 0)
+				return null;
+
+			NSMutableAttributedString? mutableAttributedString = attributedString as NSMutableAttributedString;
+			if (attributedString == null || attributedString.Length == 0)
+			{
+				mutableAttributedString = text == null ? new NSMutableAttributedString() : new NSMutableAttributedString(text);
+			}
+			else
+			{
+				mutableAttributedString = new NSMutableAttributedString(attributedString);
+
+				if (!mutableAttributedString.MutableString.ToString().Equals(text))
+				{
+					mutableAttributedString.MutableString.SetString(new NSString(text));
+				}
+			}
+
+			AddKerningAdjustment(mutableAttributedString, text, characterSpacing);
+
+			return mutableAttributedString;
+		}
+
+		internal static bool HasCharacterAdjustment(this NSMutableAttributedString mutableAttributedString)
+		{
+			if (mutableAttributedString == null)
+				return false;
+
+			var attributes = mutableAttributedString.GetAttributes(0, out NSRange removalRange);
+
+			for (uint i = 0; i < attributes.Count; i++)
+				if (attributes.Keys[i] is NSString nSString && nSString == UIStringAttributeKey.KerningAdjustment)
+					return true;
+
+			return false;
+		}
+
+		internal static void AddKerningAdjustment(NSMutableAttributedString mutableAttributedString, string? text, double characterSpacing)
+		{
+			if (!string.IsNullOrEmpty(text))
+			{
+				if (characterSpacing == 0 && !mutableAttributedString.HasCharacterAdjustment())
+					return;
+
+				mutableAttributedString.AddAttribute
+				(
+					UIStringAttributeKey.KerningAdjustment,
+					NSObject.FromObject(characterSpacing), new NSRange(0, text != null ? text.Length - 1 : 0)
+				);
+			}
+		}
+	}
+}

src/Core/src/Platform/iOS/EditorExtensions.cs

@@ -13,5 +13,15 @@ public static void UpdateText(this UITextView textView, IEditor editor)
 				textView.Text = text;
 			}
 		}
+
+		public static void UpdateCharacterSpacing(this UITextView textView, IEditor editor)
+		{
+			var textAttr = textView.AttributedText.AddCharacterSpacing(editor.Text, editor.CharacterSpacing);
+
+			if (textAttr != null)
+				textView.AttributedText = textAttr;
+
+			// TODO: Include AttributedText to Label Placeholder
+		}
 	}
 }

src/Core/tests/DeviceTests/AssertionExtensions.iOS.cs

@@ -1,6 +1,7 @@
 using System;
 using System.Threading.Tasks;
 using CoreGraphics;
+using Foundation;
 using Microsoft.Maui.Essentials;
 using UIKit;
 using Xunit;
@@ -195,5 +196,22 @@ public static UILineBreakMode ToNative(this LineBreakMode mode) =>
 			LineBreakMode.MiddleTruncation => UILineBreakMode.MiddleTruncation,
 			_ => throw new ArgumentOutOfRangeException(nameof(mode))
 		};
+
+		public static double GetCharacterSpacing(this NSAttributedString text)
+		{
+			if (text == null)
+				return 0;
+
+			var value = text.GetAttribute(UIStringAttributeKey.KerningAdjustment, 0, out var range);
+			if (value == null)
+				return 0;
+
+			Assert.Equal(0, range.Location);
+			Assert.Equal(text.Length, range.Length);
+
+			var kerning = Assert.IsType<NSNumber>(value);
+
+			return kerning.DoubleValue;
+		}
 	}
 }

src/Core/tests/DeviceTests/Handlers/Editor/EditorHandlerTests.Android.cs

@@ -1,14 +1,55 @@
-using AndroidX.AppCompat.Widget;
+using System.Threading.Tasks;
+using AndroidX.AppCompat.Widget;
+using Microsoft.Maui.DeviceTests.Stubs;
 using Microsoft.Maui.Handlers;
+using Xunit;
 
 namespace Microsoft.Maui.DeviceTests
 {
 	public partial class EditorHandlerTests
 	{
-		AppCompatEditText GetNativeEditor(EditorHandler editorHandler) =>
+        [Fact(DisplayName = "CharacterSpacing Initializes Correctly")]
+        public async Task CharacterSpacingInitializesCorrectly()
+        {
+            var xplatCharacterSpacing = 4;
+
+            var editor = new EditorStub()
+            {
+                CharacterSpacing = xplatCharacterSpacing,
+                Text = "Test"
+            };
+
+            float expectedValue = editor.CharacterSpacing.ToEm();
+
+            var values = await GetValueAsync(editor, (handler) =>
+            {
+                return new
+                {
+                    ViewValue = editor.CharacterSpacing,
+                    NativeViewValue = GetNativeCharacterSpacing(handler)
+                };
+            });
+
+            Assert.Equal(xplatCharacterSpacing, values.ViewValue);
+            Assert.Equal(expectedValue, values.NativeViewValue, EmCoefficientPrecision);
+        }
+
+        AppCompatEditText GetNativeEditor(EditorHandler editorHandler) =>
 			(AppCompatEditText)editorHandler.View;
 
 		string GetNativeText(EditorHandler editorHandler) =>
 			GetNativeEditor(editorHandler).Text;
-	}
+
+        double GetNativeCharacterSpacing(EditorHandler editorHandler)
+        {
+            var editText = GetNativeEditor(editorHandler);
+
+            if (editText != null)
+            {
+                return editText.LetterSpacing;
+            }
+
+            return -1;
+        }
+    }
 }

src/Core/tests/DeviceTests/Handlers/Editor/EditorHandlerTests.iOS.cs

@@ -1,14 +1,50 @@
-using Microsoft.Maui.Handlers;
+using System.Threading.Tasks;
+using Microsoft.Maui.DeviceTests.Stubs;
+using Microsoft.Maui.Handlers;
 using UIKit;
+using Xunit;
 
 namespace Microsoft.Maui.DeviceTests
 {
 	public partial class EditorHandlerTests
 	{
-		UITextView GetNativeEditor(EditorHandler editorHandler) =>
+        [Fact(DisplayName = "CharacterSpacing Initializes Correctly")]
+        public async Task CharacterSpacingInitializesCorrectly()
+        {
+            string originalText = "Test";
+            var xplatCharacterSpacing = 4;
+
+            var editor = new EditorStub()
+            {
+                CharacterSpacing = xplatCharacterSpacing,
+                Text = originalText
+            };
+
+            var values = await GetValueAsync(editor, (handler) =>
+            {
+                return new
+                {
+                    ViewValue = editor.CharacterSpacing,
+                    NativeViewValue = GetNativeCharacterSpacing(handler)
+                };
+            });
+
+            Assert.Equal(xplatCharacterSpacing, values.ViewValue);
+            Assert.Equal(xplatCharacterSpacing, values.NativeViewValue);
+        }
+
+        UITextView GetNativeEditor(EditorHandler editorHandler) =>
 			(UITextView)editorHandler.View;
 
 		string GetNativeText(EditorHandler editorHandler) =>
 			GetNativeEditor(editorHandler).Text;
-	}
+
+        double GetNativeCharacterSpacing(EditorHandler editorHandler)
+        {
+            var searchBar = GetNativeEditor(editorHandler);
+            var textField = searchBar.FindDescendantView<UITextField>();
+
+            return textField.AttributedText.GetCharacterSpacing();
+        }
+    }
 }

src/Core/tests/DeviceTests/TestBase.Android.cs

@@ -1,12 +1,10 @@
-using System;
-using System.Collections.Generic;
-using System.Text;
-
 namespace Microsoft.Maui.DeviceTests
 {
 	public partial class TestBase
 	{
-		public global::Android.Content.Context DefaultContext =>
+		public const int EmCoefficientPrecision = 4;
+
+		public Android.Content.Context DefaultContext =>
 			Platform.DefaultContext;
 	}
 }