perf(android): Use HashTableEx in FontHelper

Author: jeromelaban

src/Uno.UI/UI/Xaml/Extensions/FontHelper.Android.cs

@@ -15,22 +15,22 @@
 
 namespace Windows.UI.Xaml
 {
-	internal class FontHelper
-	{
-		internal static readonly Func<FontFamily, FontWeight, TypefaceStyle, Typeface> _fontFamilyToTypeFace;
+	internal partial class FontHelper
+	{ 
 		private static bool _assetsListed;
 		private static readonly string DefaultFontFamilyName = "sans-serif";
 
-		static FontHelper()
-		{
-			_fontFamilyToTypeFace = Funcs
-				.Create<FontFamily, FontWeight, TypefaceStyle, Typeface>(InternalFontFamilyToTypeFace)
-				.AsLockedMemoized();
-		}
-
 		internal static Typeface FontFamilyToTypeFace(FontFamily fontFamily, FontWeight fontWeight, TypefaceStyle style = TypefaceStyle.Normal)
-		{
-			return _fontFamilyToTypeFace(fontFamily, fontWeight, style);
+		{  
+			var entry = new FontFamilyToTypeFaceDictionary.Entry(fontFamily.Source, fontWeight, style);
+			 
+			if (!_fontFamilyToTypeFaceDictionary.TryGetValue(entry , out var typeFace))
+			{
+				typeFace = InternalFontFamilyToTypeFace(fontFamily, fontWeight, style);
+				_fontFamilyToTypeFaceDictionary.Add(entry, typeFace);
+			}
+
+			return typeFace;
 		}
 
 		internal static Typeface InternalFontFamilyToTypeFace(FontFamily fontFamily, FontWeight fontWeight, TypefaceStyle style)

src/Uno.UI/UI/Xaml/Extensions/FontHelper.Lookup.Android.cs

@@ -0,0 +1,78 @@
+using Android.App;
+using Android.Graphics;
+using System;
+using System.Collections.Generic;
+using System.Text;
+using Uno.Extensions;
+using Uno;
+using Uno.UI;
+using System.Linq;
+using Android.OS;
+using Windows.UI.Xaml.Media;
+using Windows.UI.Text;
+using Uno.Logging;
+using Microsoft.Extensions.Logging;
+using Uno.Collections;
+
+namespace Windows.UI.Xaml
+{
+	internal partial class FontHelper
+	{
+		private readonly static FontFamilyToTypeFaceDictionary _fontFamilyToTypeFaceDictionary = new FontFamilyToTypeFaceDictionary();
+
+		private class FontFamilyToTypeFaceDictionary
+		{
+			public class Entry
+			{
+				private readonly int _hashCode;
+
+				public Entry(string fontFamily, FontWeight fontWeight, TypefaceStyle style)
+				{
+					FontFamily = fontFamily;
+					FontWeight = fontWeight;
+					Style = style;
+					_hashCode = FontFamily.GetHashCode() ^ FontWeight.GetHashCode() ^ Style.GetHashCode();
+				}
+
+				public string FontFamily { get; }
+				public FontWeight FontWeight { get; }
+				public TypefaceStyle Style { get; }
+
+				public override bool Equals(object other)
+				{
+					if (other is Entry otherEntry)
+					{
+						return FontFamily == otherEntry.FontFamily
+							&& FontWeight == otherEntry.FontWeight
+							&& Style == otherEntry.Style;
+					}
+
+					return false;
+				}
+
+				public override int GetHashCode() => _hashCode;
+			}
+
+			private readonly HashtableEx _entries = new HashtableEx();
+
+			internal bool TryGetValue(Entry key, out Typeface result)
+			{
+				if (_entries.TryGetValue(key, out var value))
+				{
+					result = (Typeface)value;
+					return true;
+				}
+
+				result = null;
+				return false;
+			}
+
+			internal void Add(Entry key, Typeface typeFace)
+				=> _entries.Add(key, typeFace);
+
+			internal void Clear()
+				=> _entries.Clear();
+		}
+
+	}
+}