[Text] a bit better usage of Codepoint.ReadAt

src/Avalonia.Base/Media/TextFormatting/Unicode/Codepoint.cs

@@ -231,7 +231,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
         /// <param name="index">The index to read at.</param>
         /// <param name="count">The count of character that were read.</param>
         /// <returns></returns>
-        public static Codepoint ReadAt(ReadOnlySpan<char> text, int index, out int count)
+        public static Codepoint ReadAt(CharacterBufferRange text, int index, out int count)
         {
             count = 1;
 

src/Avalonia.Base/Media/TextFormatting/Unicode/CodepointEnumerator.cs

@@ -30,7 +30,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
                 return false;
             }
 
-            Current = Codepoint.ReadAt(_text.Span, 0, out var count);
+            Current = Codepoint.ReadAt(_text, 0, out var count);
 
             _text = _text.Skip(count);
 

src/Avalonia.Base/Media/TextFormatting/Unicode/GraphemeEnumerator.cs

@@ -245,7 +245,7 @@ namespace Avalonia.Media.TextFormatting.Unicode
 
                     if (CurrentCodeUnitOffset < _buffer.Length)
                     {
-                        CurrentCodepoint = Codepoint.ReadAt(_buffer.Span, CurrentCodeUnitOffset,
+                        CurrentCodepoint = Codepoint.ReadAt(_buffer, CurrentCodeUnitOffset,
                             out _codeUnitLengthOfCurrentScalar);
                     }
                     else

tests/Avalonia.UnitTests/MockTextShaperImpl.cs

@@ -18,7 +18,7 @@ namespace Avalonia.UnitTests
             {
                 var glyphCluster = i + text.OffsetToFirstChar;
 
-                var codepoint = Codepoint.ReadAt(characterBufferRange.Span, i, out var count);
+                var codepoint = Codepoint.ReadAt(characterBufferRange, i, out var count);
 
                 var glyphIndex = typeface.GetGlyph(codepoint);