Merge branch 'master' into extended-file-picker

src/Avalonia.Base/Media/FontManager.cs

@@ -163,7 +163,7 @@ namespace Avalonia.Media
             }
 
             //Nothing was found so use the default
-            return TryGetGlyphTypeface(new Typeface(FontFamily.DefaultFontFamilyName, typeface.Style, typeface.Weight, typeface.Stretch), out glyphTypeface);
+            return TryGetGlyphTypeface(new Typeface(DefaultFontFamily, typeface.Style, typeface.Weight, typeface.Stretch), out glyphTypeface);
 
             FontFamily GetMappedFontFamily(FontFamily fontFamily)
             {
@@ -380,6 +380,12 @@ namespace Avalonia.Media
                     "Default font family name can't be null or empty.");
             }
 
+            if (defaultFontFamilyName == FontFamily.DefaultFontFamilyName)
+            {
+                throw new InvalidOperationException(
+                    $"'{FontFamily.DefaultFontFamilyName}' is a placeholder and cannot be used as the default font family name. Provide a concrete font family name via {nameof(FontManagerOptions)} or the platform implementation.");
+            }
+
             return defaultFontFamilyName;
         }
 

src/Avalonia.Base/Media/GlyphRun.cs

@@ -708,9 +708,13 @@ namespace Avalonia.Media
                 }
             }
 
+            var ascent = GlyphTypeface.Metrics.Ascent * Scale;
+            var lineGap = GlyphTypeface.Metrics.LineGap * Scale;
+            var baseline = -ascent + lineGap * 0.5;
+
             return new GlyphRunMetrics
             {
-                Baseline = -GlyphTypeface.Metrics.Ascent * Scale,
+                Baseline = baseline,
                 Width = width,
                 WidthIncludingTrailingWhitespace = widthIncludingTrailingWhitespace,
                 Height = height,

src/Avalonia.Base/Media/TextFormatting/ShapedTextRun.cs

@@ -36,7 +36,7 @@ namespace Avalonia.Media.TextFormatting
 
         public TextMetrics TextMetrics { get; }
 
-        public override double Baseline => -TextMetrics.Ascent;
+        public override double Baseline => -TextMetrics.Ascent + TextMetrics.LineGap * 0.5;
 
         public override Size Size => GlyphRun.Bounds.Size;
 

src/Avalonia.Base/Media/TextFormatting/TextLineImpl.cs

@@ -580,7 +580,7 @@ namespace Avalonia.Media.TextFormatting
         /// </returns>
         private int GetLastDirectionalRunIndex(int indexedRunIndex, FlowDirection flowDirection, ref double directionalWidth)
         {
-            if(_indexedTextRuns is null)
+            if (_indexedTextRuns is null)
             {
                 return -1;
             }
@@ -624,7 +624,7 @@ namespace Avalonia.Media.TextFormatting
 
         public override IReadOnlyList<TextBounds> GetTextBounds(int firstTextSourceIndex, int textLength)
         {
-            if(textLength == 0)
+            if (textLength == 0)
             {
                 throw new ArgumentOutOfRangeException(nameof(textLength), textLength, $"{nameof(textLength)} ('0') must be a non-zero value. ");
             }
@@ -643,7 +643,7 @@ namespace Avalonia.Media.TextFormatting
                 var indexedTextRun = _indexedTextRuns[0];
                 var currentDirection = GetRunDirection(indexedTextRun.TextRun, _resolvedFlowDirection);
 
-                return [new TextBounds(new Rect(0,0,0, Height), currentDirection, [])];
+                return [new TextBounds(new Rect(0, 0, 0, Height), currentDirection, [])];
             }
 
             //We can return early if the requested text range is after the line's text range.
@@ -667,7 +667,7 @@ namespace Avalonia.Media.TextFormatting
                 {
                     break;
                 }
-   
+
                 var currentTextRun = currentIndexedRun.TextRun;
 
                 if (currentTextRun == null)
@@ -691,7 +691,7 @@ namespace Avalonia.Media.TextFormatting
                 {
                     directionalWidth = currentDrawable.Size.Width;
                 }
-    
+
                 var firstRunIndex = currentIndexedRun.RunIndex;
                 var lastRunIndex = GetLastDirectionalRunIndex(indexedRunIndex, currentDirection, ref directionalWidth);
 
@@ -709,8 +709,8 @@ namespace Avalonia.Media.TextFormatting
                         }
                     default:
                         {
-                             currentBounds = GetTextBoundsLeftToRight(firstRunIndex, lastRunIndex, currentX, firstTextSourceIndex,
-                                    currentPosition, remainingLength, out coveredLength, out currentPosition);
+                            currentBounds = GetTextBoundsLeftToRight(firstRunIndex, lastRunIndex, currentX, firstTextSourceIndex,
+                                   currentPosition, remainingLength, out coveredLength, out currentPosition);
 
                             break;
                         }
@@ -729,7 +729,7 @@ namespace Avalonia.Media.TextFormatting
 
                 lastBounds = currentBounds;
 
-                if(coveredLength <= 0)
+                if (coveredLength <= 0)
                 {
                     throw new InvalidOperationException("Covered length must be greater than zero.");
                 }
@@ -814,7 +814,7 @@ namespace Avalonia.Media.TextFormatting
             }
         }
 
-        private CharacterHit GetPreviousCharacterHit(CharacterHit characterHit, bool useGraphemeBoundaries)
+        private CharacterHit GetPreviousCharacterHit(CharacterHit characterHit, bool isBackspaceDelete)
         {
             if (_textRuns.Length == 0 || _indexedTextRuns is null)
             {
@@ -833,8 +833,6 @@ namespace Avalonia.Media.TextFormatting
                 return new CharacterHit(FirstTextSourceIndex);
             }
 
-            var currentCharacterHit = characterHit;
-
             var currentRun = GetRunAtCharacterIndex(characterIndex, LogicalDirection.Backward, out var currentPosition);
 
             var previousCharacterHit = characterHit;
@@ -843,46 +841,38 @@ namespace Avalonia.Media.TextFormatting
             {
                 case ShapedTextRun shapedRun:
                     {
-                        var offset = Math.Max(0, currentPosition - shapedRun.GlyphRun.Metrics.FirstCluster);
+                        //Determine the start of the first hit in local positions.
+                        var runOffset = Math.Max(0, characterIndex - currentPosition);
 
-                        if (offset > 0)
-                        {
-                            currentCharacterHit = new CharacterHit(Math.Max(0, characterHit.FirstCharacterIndex - offset), characterHit.TrailingLength);
-                        }
+                        var firstCluster = shapedRun.GlyphRun.Metrics.FirstCluster;
 
-                        previousCharacterHit = shapedRun.GlyphRun.GetPreviousCaretCharacterHit(currentCharacterHit);
+                        //Current position is a text source index and first cluster is relative to the GlyphRun's buffer.
+                        var textSourceOffset = currentPosition - firstCluster;
 
-                        if (useGraphemeBoundaries)
+                        if (isBackspaceDelete)
                         {
-                            var textPosition = Math.Max(0, previousCharacterHit.FirstCharacterIndex - shapedRun.GlyphRun.Metrics.FirstCluster);
-
-                            var text = shapedRun.GlyphRun.Characters.Slice(textPosition);
-
-                            var graphemeEnumerator = new GraphemeEnumerator(text.Span);
-
                             var length = 0;
 
-                            var clusterLength = Math.Max(0, currentCharacterHit.FirstCharacterIndex + currentCharacterHit.TrailingLength - 
-                                previousCharacterHit.FirstCharacterIndex - previousCharacterHit.TrailingLength);
-
-                            while (graphemeEnumerator.MoveNext(out var grapheme))
+                            while (Codepoint.ReadAt(shapedRun.GlyphRun.Characters.Span, length, out var count) != Codepoint.ReplacementCodepoint)
                             {
-                                if (length + grapheme.Length < clusterLength)
+                                if (length + count >= runOffset)
                                 {
-                                    length += grapheme.Length;
-
-                                    continue;
+                                    break;
                                 }
 
-                                previousCharacterHit = new CharacterHit(previousCharacterHit.FirstCharacterIndex + length);
-
-                                break;
+                                length += count;
                             }
-                        }
 
-                        if (offset > 0)
+                            previousCharacterHit = new CharacterHit(characterIndex - runOffset + length);
+                        }
+                        else
                         {
-                            previousCharacterHit = new CharacterHit(previousCharacterHit.FirstCharacterIndex + offset, previousCharacterHit.TrailingLength);
+                            previousCharacterHit = shapedRun.GlyphRun.GetPreviousCaretCharacterHit(new CharacterHit(firstCluster + runOffset));
+
+                            if(textSourceOffset > 0)
+                            {
+                                previousCharacterHit = new CharacterHit(textSourceOffset + previousCharacterHit.FirstCharacterIndex, previousCharacterHit.TrailingLength);
+                            }
                         }
 
                         break;
@@ -998,14 +988,14 @@ namespace Avalonia.Media.TextFormatting
                 {
                     var runBounds = GetRunBounds(shapedTextRun, endX, firstTextSourceIndex, remainingLength, currentPosition);
 
-                    if(runBounds.TextSourceCharacterIndex < FirstTextSourceIndex + Length)
+                    if (runBounds.TextSourceCharacterIndex < FirstTextSourceIndex + Length)
                     {
                         textRunBounds.Add(runBounds);
                     }
 
                     currentPosition = runBounds.TextSourceCharacterIndex + runBounds.Length;
 
-                    if(i == firstRunIndex)
+                    if (i == firstRunIndex)
                     {
                         startX = runBounds.Rectangle.Left;
                     }
@@ -1122,7 +1112,7 @@ namespace Avalonia.Media.TextFormatting
             var startHitIndex = startHit.FirstCharacterIndex;
 
             //If the requested text range starts at the trailing edge we need to move at the end of the hit
-            if(startHitIndex < startIndex)
+            if (startHitIndex < startIndex)
             {
                 startHitIndex += startHit.TrailingLength;
             }
@@ -1240,7 +1230,7 @@ namespace Avalonia.Media.TextFormatting
                         }
                     case not null:
                         {
-                            if(direction == LogicalDirection.Forward)
+                            if (direction == LogicalDirection.Forward)
                             {
                                 if (textPosition == codepointIndex)
                                 {
@@ -1326,8 +1316,6 @@ namespace Avalonia.Media.TextFormatting
                 }
             }
 
-            var height = descent - ascent + lineGap;
-
             var inkBounds = new Rect();
 
             for (var index = 0; index < _textRuns.Length; index++)
@@ -1335,31 +1323,53 @@ namespace Avalonia.Media.TextFormatting
                 switch (_textRuns[index])
                 {
                     case ShapedTextRun textRun:
-                    {
-                        var glyphRun = textRun.GlyphRun;
-                        //Align the ink bounds at the common baseline
-                        var offsetY = -ascent - textRun.Baseline;
+                        {
+                            var glyphRun = textRun.GlyphRun;
+                            //Align the ink bounds at the common baseline
+                            var offsetY = -ascent - textRun.Baseline;
 
-                        var runBounds = glyphRun.InkBounds.Translate(new Vector(widthIncludingWhitespace, offsetY));
+                            var runBounds = glyphRun.InkBounds.Translate(new Vector(widthIncludingWhitespace, offsetY));
 
-                        inkBounds = inkBounds.Union(runBounds);
+                            inkBounds = inkBounds.Union(runBounds);
 
-                        widthIncludingWhitespace += textRun.Size.Width;
+                            widthIncludingWhitespace += textRun.Size.Width;
 
-                        break;
-                    }
+                            break;
+                        }
 
                     case DrawableTextRun drawableTextRun:
-                    {
-                        //Align the bounds at the common baseline
-                        var offsetY = -ascent - drawableTextRun.Baseline;
+                        {
+                            //Align the bounds at the common baseline
+                            var offsetY = -ascent - drawableTextRun.Baseline;
 
-                        inkBounds = inkBounds.Union(new Rect(new Point(widthIncludingWhitespace, offsetY), drawableTextRun.Size));
+                            inkBounds = inkBounds.Union(new Rect(new Point(widthIncludingWhitespace, offsetY), drawableTextRun.Size));
 
-                        widthIncludingWhitespace += drawableTextRun.Size.Width;
-                        
-                        break;
-                    }
+                            widthIncludingWhitespace += drawableTextRun.Size.Width;
+
+                            break;
+                        }
+                }
+            }
+
+            var halfLineGap = lineGap * 0.5;
+            var naturalHeight = descent - ascent + lineGap;
+            var baseline = -ascent + halfLineGap;
+            var height = naturalHeight;
+
+            if (!double.IsNaN(lineHeight) && !MathUtilities.IsZero(lineHeight))
+            {
+                if (lineHeight <= naturalHeight)
+                {
+                    //Clamp to the specified line height
+                    height = lineHeight;
+                    baseline = -ascent;
+                }
+                else
+                {
+                    // Center the text vertically within the specified line height
+                    height = lineHeight;
+                    var extra = lineHeight - (descent - ascent);
+                    baseline = -ascent + extra / 2;
                 }
             }
 
@@ -1395,24 +1405,14 @@ namespace Avalonia.Media.TextFormatting
             }
 
             var extent = inkBounds.Height;
-            //The width of overhanging pixels at the bottom
-            var overhangAfter = inkBounds.Bottom - height;
+            //The height of overhanging pixels at the bottom
+            var overhangAfter = inkBounds.Bottom - height + halfLineGap;
             //The width of overhanging pixels at the natural alignment point. Positive value means we are inside.
             var overhangLeading = inkBounds.Left;
             //The width of overhanging pixels at the end of the natural bounds. Positive value means we are inside.
             var overhangTrailing = widthIncludingWhitespace - inkBounds.Right;
             var hasOverflowed = width > _paragraphWidth;
 
-            if (!double.IsNaN(lineHeight) && !MathUtilities.IsZero(lineHeight))
-            {
-                //Center the line
-                var offset = (height - lineHeight) / 2;
-
-                ascent += offset;
-
-                height = lineHeight;
-            }
-
             var start = GetParagraphOffsetX(width, widthIncludingWhitespace);
 
             _inkBounds = inkBounds.Translate(new Vector(start, 0));
@@ -1426,7 +1426,7 @@ namespace Avalonia.Media.TextFormatting
                 Extent = extent,
                 NewlineLength = newLineLength,
                 Start = start,
-                TextBaseline = -ascent,
+                TextBaseline = baseline,
                 TrailingWhitespaceLength = trailingWhitespaceLength,
                 Width = width,
                 WidthIncludingTrailingWhitespace = widthIncludingWhitespace,

src/Avalonia.Base/Media/TextFormatting/TextMetrics.cs

@@ -19,6 +19,8 @@
 
             LineGap = fontMetrics.LineGap * scale;
 
+            Baseline = -Ascent + LineGap * 0.5;
+
             LineHeight = Descent - Ascent + LineGap;
 
             UnderlineThickness = fontMetrics.UnderlineThickness * scale;
@@ -35,6 +37,11 @@
         /// </summary>
         public double FontRenderingEmSize { get; }
 
+        /// <summary>
+        /// Gets the distance from the top to the baseline of the line of text.
+        /// </summary>
+        public double Baseline { get; }
+
         /// <summary>
         /// Gets the recommended distance above the baseline.
         /// </summary>

src/Avalonia.Themes.Fluent/Controls/CheckBox.xaml

@@ -13,6 +13,7 @@
   </Design.PreviewWith>
 
   <StreamGeometry x:Key="CheckMarkPathData">M5.5 10.586 1.707 6.793A1 1 0 0 0 .293 8.207l4.5 4.5a1 1 0 0 0 1.414 0l11-11A1 1 0 0 0 15.793.293L5.5 10.586Z</StreamGeometry>
+  <x:Double x:Key="CheckBoxMinHeight">32</x:Double> 
   
   <ControlTheme x:Key="{x:Type CheckBox}" TargetType="CheckBox">
     <Setter Property="Padding" Value="8,0,0,0" />
@@ -21,7 +22,7 @@
     <Setter Property="HorizontalContentAlignment" Value="Left" />
     <Setter Property="VerticalContentAlignment" Value="Center" />
     <Setter Property="CornerRadius" Value="{DynamicResource ControlCornerRadius}" />
-    <Setter Property="MinHeight" Value="32" />
+    <Setter Property="MinHeight" Value="{DynamicResource CheckBoxMinHeight}" />
     <Setter Property="Foreground" Value="{DynamicResource CheckBoxForegroundUnchecked}" />
     <Setter Property="Background" Value="{DynamicResource CheckBoxBackgroundUnchecked}" />
     <Setter Property="BorderBrush" Value="{DynamicResource CheckBoxBorderBrushUnchecked}" />
@@ -35,7 +36,7 @@
                   BorderThickness="{TemplateBinding BorderThickness}"
                   CornerRadius="{TemplateBinding CornerRadius}" />
 
-          <Grid VerticalAlignment="Top" Height="32">
+          <Grid VerticalAlignment="Top" Height="{DynamicResource CheckBoxMinHeight}">
             <Border x:Name="NormalRectangle"
                     BorderBrush="{DynamicResource CheckBoxCheckBackgroundStrokeUnchecked}"
                     Background="{DynamicResource CheckBoxCheckBackgroundFillUnchecked}"

src/Avalonia.Themes.Fluent/Controls/RadioButton.xaml

@@ -11,6 +11,8 @@
     </Border>
   </Design.PreviewWith>
   
+  <x:Double x:Key="RadioButtonMinHeight">32</x:Double>
+  
   <ControlTheme x:Key="{x:Type RadioButton}" TargetType="RadioButton">
     <Setter Property="Background" Value="{DynamicResource RadioButtonBackground}" />
     <Setter Property="Foreground" Value="{DynamicResource RadioButtonForeground}" />
@@ -30,7 +32,7 @@
             BorderThickness="{TemplateBinding BorderThickness}"
             CornerRadius="{TemplateBinding CornerRadius}">
           <Grid ColumnDefinitions="20,*">
-            <Grid Height="32" VerticalAlignment="Top">
+            <Grid Height="{DynamicResource RadioButtonMinHeight}" VerticalAlignment="Top">
 
               <Ellipse
                   Name="OuterEllipse"

src/Avalonia.Themes.Fluent/DensityStyles/Compact.xaml

@@ -21,4 +21,6 @@
   <x:Double x:Key="TabItemMinHeight">28</x:Double>
   <Thickness x:Key="TabItemHeaderMargin">6, 0</Thickness>
   <Thickness x:Key="ButtonPadding">6,4</Thickness>
+  <x:Double x:Key="CheckBoxMinHeight">24</x:Double>
+  <x:Double x:Key="RadioButtonMinHeight">24</x:Double>
 </ResourceDictionary>

tests/Avalonia.Skia.UnitTests/Media/GlyphRunTests.cs

@@ -70,7 +70,7 @@ namespace Avalonia.Skia.UnitTests.Media
                 var rects = BuildRects(glyphRun);
 
                 rects.Reverse();
-                
+
                 if (glyphRun.IsLeftToRight)
                 {
                     foreach (var rect in rects)
@@ -95,7 +95,7 @@ namespace Avalonia.Skia.UnitTests.Media
                 }
             }
         }
-        
+
         [InlineData("ABC012345", 0)] //LeftToRight
         [InlineData("זה כיף סתם לשמוע איך תנצח קרפד עץ טוב בגן", 1)] //RightToLeft
         [Theory]
@@ -113,19 +113,19 @@ namespace Avalonia.Skia.UnitTests.Media
                 {
                     var characterHit =
                         glyphRun.GetCharacterHitFromDistance(glyphRun.Bounds.Width, out _);
-                    
+
                     Assert.Equal(glyphRun.Characters.Length, characterHit.FirstCharacterIndex + characterHit.TrailingLength);
                 }
                 else
                 {
-                     var characterHit =
-                        glyphRun.GetCharacterHitFromDistance(0, out _);
-                    
+                    var characterHit =
+                       glyphRun.GetCharacterHitFromDistance(0, out _);
+
                     Assert.Equal(glyphRun.Characters.Length, characterHit.FirstCharacterIndex + characterHit.TrailingLength);
                 }
-                
+
                 var rects = BuildRects(glyphRun);
-                
+
                 var lastCluster = -1;
                 var index = 0;
 
@@ -379,12 +379,31 @@ namespace Avalonia.Skia.UnitTests.Media
             }
         }
 
+        [Fact]
+        public void Should_Add_Half_LineGap_To_Baseline()
+        {
+            using (Start())
+            {
+                var typeface = new Typeface("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Inter");
+                var options = new TextShaperOptions(typeface.GlyphTypeface, 14);
+                var shapedBuffer = TextShaper.Current.ShapeText("F", options);
+
+                var textMetrics = new TextMetrics(shapedBuffer.GlyphTypeface, 14);
+
+                var glyphRun = CreateGlyphRun(shapedBuffer);
+
+                var expectedBaseline = -textMetrics.Ascent + textMetrics.LineGap / 2;
+
+                Assert.Equal(expectedBaseline, glyphRun.Metrics.Baseline);
+            }
+        }
+
         private static List<Rect> BuildRects(GlyphRun glyphRun)
         {
             var height = glyphRun.Bounds.Height;
 
             var currentX = glyphRun.IsLeftToRight ? 0d : glyphRun.Bounds.Width;
-            
+
             var rects = new List<Rect>(glyphRun.GlyphInfos!.Count);
 
             var lastCluster = -1;
@@ -392,7 +411,7 @@ namespace Avalonia.Skia.UnitTests.Media
             for (var index = 0; index < glyphRun.GlyphInfos.Count; index++)
             {
                 var currentCluster = glyphRun.GlyphInfos[index].GlyphCluster;
-                
+
                 var advance = glyphRun.GlyphInfos[index].GlyphAdvance;
 
                 if (lastCluster != currentCluster)
@@ -412,11 +431,11 @@ namespace Avalonia.Skia.UnitTests.Media
 
                     rects.Remove(rect);
 
-                    rect = glyphRun.IsLeftToRight ? 
-                        rect.WithWidth(rect.Width + advance) : 
+                    rect = glyphRun.IsLeftToRight ?
+                        rect.WithWidth(rect.Width + advance) :
                         new Rect(rect.X - advance, 0, rect.Width + advance, height);
-                    
-                   rects.Add(rect);
+
+                    rects.Add(rect);
                 }
 
                 if (glyphRun.IsLeftToRight)
@@ -436,14 +455,14 @@ namespace Avalonia.Skia.UnitTests.Media
 
         private static GlyphRun CreateGlyphRun(ShapedBuffer shapedBuffer)
         {
-            var glyphRun =  new GlyphRun(
+            var glyphRun = new GlyphRun(
                 shapedBuffer.GlyphTypeface,
                 shapedBuffer.FontRenderingEmSize,
                 shapedBuffer.Text,
                 shapedBuffer,
                 biDiLevel: shapedBuffer.BidiLevel);
 
-            if(shapedBuffer.BidiLevel == 1)
+            if (shapedBuffer.BidiLevel == 1)
             {
                 shapedBuffer.Reverse();
             }

tests/Avalonia.Skia.UnitTests/Media/TextFormatting/TextLineTests.cs

@@ -9,7 +9,6 @@ using Avalonia.Media;
 using Avalonia.Media.TextFormatting;
 using Avalonia.UnitTests;
 using Xunit;
-using static System.Net.Mime.MediaTypeNames;
 
 namespace Avalonia.Skia.UnitTests.Media.TextFormatting
 {
@@ -905,7 +904,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
                 Assert.NotNull(textLine);
 
                 Assert.Throws<ArgumentOutOfRangeException>(() => textLine.GetTextBounds(0, 0));
-            }     
+            }
         }
 
         [Fact]
@@ -983,12 +982,12 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
 
                 var defaultProperties = new GenericTextRunProperties(typeface);
                 var textSource = new CustomTextBufferTextSource(
-                    new TextHidden(1), 
-                    new TextCharacters("Authenti", defaultProperties), 
-                    new TextHidden(1), 
+                    new TextHidden(1),
+                    new TextCharacters("Authenti", defaultProperties),
+                    new TextHidden(1),
                     new TextHidden(1),
                     new TextCharacters("ff", defaultProperties),
-                    new TextHidden(1), 
+                    new TextHidden(1),
                     new TextHidden(1));
 
                 var formatter = new TextFormatterImpl();
@@ -1138,7 +1137,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
                 var typeface = new Typeface(FontFamily.Parse("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Manrope"));
                 var defaultProperties = new GenericTextRunProperties(typeface);
                 var textSource = new CustomTextBufferTextSource(
-                    new TextCharacters("He", defaultProperties), 
+                    new TextCharacters("He", defaultProperties),
                     new TextCharacters("Wo", defaultProperties),
                     new TextCharacters("ff", defaultProperties));
 
@@ -1249,6 +1248,29 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
             }
         }
 
+        [Fact]
+        public void Should_Get_In_Cluster_Backspace_Hit()
+        {
+            using (Start())
+            {
+                var typeface = new Typeface(FontFamily.Parse("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Manrope"));
+                var defaultProperties = new GenericTextRunProperties(typeface);
+                var textSource = new SingleBufferTextSource("ff", defaultProperties);
+
+                var formatter = new TextFormatterImpl();
+
+                var textLine =
+                    formatter.FormatLine(textSource, 0, double.PositiveInfinity,
+                        new GenericTextParagraphProperties(defaultProperties));
+
+                Assert.NotNull(textLine);
+
+                var backspaceHit = textLine.GetBackspaceCaretCharacterHit(new CharacterHit(1, 1));
+
+                Assert.Equal(1, backspaceHit.FirstCharacterIndex);
+            }
+        }
+
         private class TextHidden : TextRun
         {
             public TextHidden(int length)
@@ -1272,11 +1294,11 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
             {
                 var pos = 0;
 
-                for(var i = 0; i < _textRuns.Count; i++)
+                for (var i = 0; i < _textRuns.Count; i++)
                 {
                     var currentRun = _textRuns[i];
 
-                    if(pos + currentRun.Length > textSourceIndex)
+                    if (pos + currentRun.Length > textSourceIndex)
                     {
                         return currentRun;
                     }
@@ -1638,7 +1660,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
                 Assert.True(firstBounds.TextRunBounds.Count > 0);
             }
         }
-        
+
         [Fact]
         public void Should_GetTextBounds_NotInfiniteLoop()
         {
@@ -1809,7 +1831,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
             {
                 var defaultProperties = new GenericTextRunProperties(Typeface.Default);
 
-                var textSource = new TextFormatterTests.ListTextSource(new TextHidden(1) ,new TextCharacters(text, defaultProperties));
+                var textSource = new TextFormatterTests.ListTextSource(new TextHidden(1), new TextCharacters(text, defaultProperties));
 
                 var formatter = new TextFormatterImpl();
 
@@ -1925,7 +1947,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
 
                 var textPosition = 0;
 
-                while(textPosition < text.Length)
+                while (textPosition < text.Length)
                 {
                     var bounds = textLine.GetTextBounds(textPosition, 1);
 
@@ -2081,7 +2103,7 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
 
                 foreach (var glyphInfo in firstRun.ShapedBuffer)
                 {
-                    if(lastCluster != glyphInfo.GlyphCluster)
+                    if (lastCluster != glyphInfo.GlyphCluster)
                     {
                         clusterWidth.Add(currentAdvance);
                         distances.Add(currentDistance);
@@ -2173,6 +2195,96 @@ namespace Avalonia.Skia.UnitTests.Media.TextFormatting
             }
         }
 
+        [Fact]
+        public void Should_Add_Half_LineGap_To_Baseline()
+        {
+            using (Start())
+            {
+                var typeface = new Typeface("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Inter");
+                var defaultProperties = new GenericTextRunProperties(typeface);
+
+                var textSource = new SingleBufferTextSource("F", defaultProperties);
+
+                var formatter = new TextFormatterImpl();
+
+                var textLine =
+                    formatter.FormatLine(textSource, 0, double.PositiveInfinity,
+                        new GenericTextParagraphProperties(defaultProperties));
+
+                Assert.NotNull(textLine);
+
+                var textMetrics = new TextMetrics(typeface.GlyphTypeface, 12);
+
+                var expectedBaseline = -textMetrics.Ascent + textMetrics.LineGap / 2;
+
+                Assert.Equal(expectedBaseline, textLine.Baseline);
+            }
+        }
+
+        [Fact]
+        public void Should_Clamp_Baseline_When_LineHeight_Is_Smaller_Than_Natural()
+        {
+            using (Start())
+            {
+                var typeface = new Typeface("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Inter");
+                var defaultProperties = new GenericTextRunProperties(typeface);
+
+                var textSource = new SingleBufferTextSource("F", defaultProperties);
+
+                var formatter = new TextFormatterImpl();
+
+                var textMetrics = new TextMetrics(typeface.GlyphTypeface, 12);
+                var natural = -textMetrics.Ascent + textMetrics.Descent + textMetrics.LineGap;
+
+                var smallerLineHeight = natural - 2;
+
+                // Force a smaller line height than ascent+descent+lineGap
+                var paragraphProps = new GenericTextParagraphProperties(defaultProperties, lineHeight: smallerLineHeight);
+
+                var textLine = formatter.FormatLine(textSource, 0, double.PositiveInfinity, paragraphProps);
+
+                Assert.NotNull(textLine);
+
+                // In this case, baseline should equal -Ascent (lineGap ignored)
+                var expectedBaseline = -textMetrics.Ascent;
+
+                Assert.Equal(expectedBaseline, textLine.Baseline);
+                Assert.Equal(paragraphProps.LineHeight, textLine.Height);
+            }
+        }
+
+        [Fact]
+        public void Should_Distribute_Extra_Space_When_LineHeight_Is_Larger_Than_Natural()
+        {
+            using (Start())
+            {
+                var typeface = new Typeface("resm:Avalonia.Skia.UnitTests.Fonts?assembly=Avalonia.Skia.UnitTests#Inter");
+                var defaultProperties = new GenericTextRunProperties(typeface);
+
+                var textSource = new SingleBufferTextSource("F", defaultProperties);
+
+                var formatter = new TextFormatterImpl();
+
+                var textMetrics = new TextMetrics(typeface.GlyphTypeface, 12);
+                var natural = -textMetrics.Ascent + textMetrics.Descent + textMetrics.LineGap;
+
+                var largerLineHeight = natural + 50;
+
+                var paragraphProps = new GenericTextParagraphProperties(defaultProperties, lineHeight: largerLineHeight);
+
+                var textLine = formatter.FormatLine(textSource, 0, double.PositiveInfinity, paragraphProps);
+
+                Assert.NotNull(textLine);
+
+                // Extra space is distributed evenly above and below
+                var extra = largerLineHeight - (textMetrics.Descent - textMetrics.Ascent);
+                var expectedBaseline = -textMetrics.Ascent + extra / 2;
+
+                Assert.Equal(expectedBaseline, textLine.Baseline, 5);
+                Assert.Equal(largerLineHeight, textLine.Height, 5);
+            }
+        }
+
         private class FixedRunsTextSource : ITextSource
         {
             private readonly IReadOnlyList<TextRun> _textRuns;