Ensure glyphs are not overwritten by fallbacks.

SixLabors.Fonts.sln

@@ -73,6 +73,8 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = "UnicodeTestData", "UnicodeT
 EndProject
 Project("{9A19103F-16F7-4668-BE54-9A1E7A4F7556}") = "SixLabors.Fonts.Benchmarks", "tests\SixLabors.Fonts.Benchmarks\SixLabors.Fonts.Benchmarks\SixLabors.Fonts.Benchmarks.csproj", "{FB8FDC5F-7FEB-4132-9133-C25E05C0B3D9}"
 EndProject
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "DrawWithImageSharp", "samples\DrawWithImageSharp\DrawWithImageSharp.csproj", "{01863664-6C7E-61F2-F74B-7D451FFDC3C2}"
+EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -99,6 +101,10 @@ Global
 		{FB8FDC5F-7FEB-4132-9133-C25E05C0B3D9}.Debug|Any CPU.Build.0 = Debug|Any CPU
 		{FB8FDC5F-7FEB-4132-9133-C25E05C0B3D9}.Release|Any CPU.ActiveCfg = Release|Any CPU
 		{FB8FDC5F-7FEB-4132-9133-C25E05C0B3D9}.Release|Any CPU.Build.0 = Release|Any CPU
+		{01863664-6C7E-61F2-F74B-7D451FFDC3C2}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{01863664-6C7E-61F2-F74B-7D451FFDC3C2}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{01863664-6C7E-61F2-F74B-7D451FFDC3C2}.Release|Any CPU.ActiveCfg = Release|Any CPU
+		{01863664-6C7E-61F2-F74B-7D451FFDC3C2}.Release|Any CPU.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -113,6 +119,7 @@ Global
 		{ABB6E111-672F-4846-88D6-C49C6CD01606} = {249327CF-1415-428B-8EEA-8C7705B1DE8F}
 		{654DD381-B93D-4459-B669-296F5D9172ED} = {56801022-D71A-4FBE-BC5B-CBA08E2284EC}
 		{FB8FDC5F-7FEB-4132-9133-C25E05C0B3D9} = {56801022-D71A-4FBE-BC5B-CBA08E2284EC}
+		{01863664-6C7E-61F2-F74B-7D451FFDC3C2} = {71A3911C-D6B9-4EBE-9691-2FE28BDF462E}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {38F4B47F-4F74-40F5-8707-C0EF1D0BDF92}

samples/DrawWithImageSharp/DrawWithImageSharp.csproj

@@ -46,8 +46,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <PackageReference Include="SixLabors.ImageSharp.Drawing" Version="2.1.4" />
-    <PackageReference Include="System.ValueTuple" Version="4.5.0" />
+    <PackageReference Include="SixLabors.ImageSharp.Drawing" Version="3.0.0-alpha.0.6" />
   </ItemGroup>
 
 </Project>

samples/DrawWithImageSharp/Program.cs

@@ -9,6 +9,7 @@
 using SixLabors.ImageSharp.Drawing;
 using SixLabors.ImageSharp.Drawing.Processing;
 using SixLabors.ImageSharp.Drawing.Processing.Processors.Text;
+using SixLabors.ImageSharp.Drawing.Text;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using IOPath = System.IO.Path;
@@ -21,15 +22,15 @@
     {
         var fonts = new FontCollection();
         var woffFonts = new FontCollection();
         FontFamily font = fonts.Add(IOPath.Combine("Fonts", "SixLaborsSampleAB.ttf"));
         FontFamily fontWoff = woffFonts.Add(IOPath.Combine("Fonts", "SixLaborsSampleAB.woff"));
         FontFamily fontWoff2 = woffFonts.Add(IOPath.Combine("Fonts", "OpenSans-Regular.woff2"));
         FontFamily carter = fonts.Add(IOPath.Combine("Fonts", "CarterOne.ttf"));
         FontFamily wendyOne = fonts.Add(IOPath.Combine("Fonts", "WendyOne-Regular.ttf"));
         FontFamily whitneyBook = fonts.Add(IOPath.Combine("Fonts", "whitney-book.ttf"));
         FontFamily colorEmoji = fonts.Add(IOPath.Combine("Fonts", "Twemoji Mozilla.ttf"));
         FontFamily openSans = fonts.Add(IOPath.Combine("Fonts", "OpenSans-Regular.ttf"));
         FontFamily sunflower = fonts.Add(IOPath.Combine("Fonts", "Sunflower-Medium.ttf"));
         FontFamily bugzilla = fonts.Add(IOPath.Combine("Fonts", "me_quran_volt_newmet.ttf"));
 
         FontFamily notoKR = fonts.Add(IOPath.Combine("Fonts", "NotoSansKR-Regular.otf"));
@@ -75,10 +76,10 @@
             });
 
         return;
         RenderText(arial, "abcdefghijklmnopqrstuvwxyz", pointSize: 30);
         RenderText(arial, "abcdefghijklmnopqrstuvwxyz\r\nabcdefghijklmnopqrstuvwxyz", pointSize: 30);
         RenderText(arial, "abcdef ghijk lmnopq rstuvwxyz", pointSize: 30);
         // return;
 
         var textRuns = new List<RichTextRun>
         {
@@ -218,7 +219,7 @@
         using var img = new Image<Rgba32>(width, height);
         img.Mutate(x => x.Fill(Color.White));
 
-        IPathCollection shapes = TextBuilder.GenerateGlyphs(text, new RichTextOptions(font) { Origin = new Vector2(50f, 4f) });
+        IPathCollection shapes = TextBuilder.GeneratePaths(text, new RichTextOptions(font) { Origin = new Vector2(50f, 4f) });
         img.Mutate(x => x.Fill(Color.Black, shapes));
 
         Directory.CreateDirectory(IOPath.GetDirectoryName(fullPath));
@@ -288,9 +289,9 @@
         float pointSize = 12,
         IEnumerable<FontFamily> fallbackFonts = null)
     {
         foreach (VerticalAlignment va in (VerticalAlignment[])Enum.GetValues(typeof(VerticalAlignment)))
         {
             foreach (HorizontalAlignment ha in (HorizontalAlignment[])Enum.GetValues(typeof(HorizontalAlignment)))
             {
                 Font font = new(fontFamily, pointSize);
                 RichTextOptions textOptions = new(font)
@@ -320,8 +321,8 @@
 
                 img[size.Width / 2, size.Height / 2] = Color.White.ToPixel<Rgba32>();
 
                 string h = ha.ToString().Replace(nameof(HorizontalAlignment), string.Empty).ToLower();
                 string v = va.ToString().Replace(nameof(VerticalAlignment), string.Empty).ToLower();
 
                 string fullPath = CreatePath(font.Name, text + "-" + h + "-" + v + ".png");
                 Directory.CreateDirectory(IOPath.GetDirectoryName(fullPath));
@@ -365,7 +366,7 @@
 
         var sb = new StringBuilder();
         IEnumerable<ISimplePath> converted = shape.Flatten();
         converted.Aggregate(sb, (s, p) =>
         {
             ReadOnlySpan<PointF> points = p.Points.Span;
             for (int i = 0; i < points.Length; i++)

src/SixLabors.Fonts/GlyphPositioningCollection.cs

@@ -17,7 +17,7 @@ internal sealed class GlyphPositioningCollection : IGlyphShapingCollection
     /// <summary>
     /// Contains a map the index of a map within the collection, non-sequential codepoint offsets, and their glyph ids, point size, and mtrics.
     /// </summary>
-    private readonly List<GlyphPositioningData> glyphs = new();
+    private readonly List<GlyphPositioningData> glyphs = [];
 
     /// <summary>
     /// Initializes a new instance of the <see cref="GlyphPositioningCollection"/> class.
@@ -149,6 +149,11 @@ public bool TryUpdate(Font font, GlyphSubstitutionCollection collection)
         ColorFontSupport colorFontSupport = this.TextOptions.ColorFontSupport;
         bool hasFallBacks = false;
         List<int> orphans = [];
+
+        Tag vert = FeatureTags.VerticalAlternates;
+        Tag vrt2 = FeatureTags.VerticalAlternatesAndRotation;
+        Tag vrtr = FeatureTags.VerticalAlternatesForRotation;
+
         for (int i = 0; i < this.glyphs.Count; i++)
         {
             GlyphPositioningData current = this.glyphs[i];
@@ -173,6 +178,15 @@ public bool TryUpdate(Font font, GlyphSubstitutionCollection collection)
                     // cache the original in the font metrics and only update our collection.
                     TextAttributes textAttributes = shape.TextRun.TextAttributes;
                     TextDecorations textDecorations = shape.TextRun.TextDecorations;
+
+                    bool isVertical = AdvancedTypographicUtils.IsVerticalGlyph(codePoint, layoutMode);
+                    foreach (Tag feature in shape.AppliedFeatures)
+                    {
+                        isVertical |= feature == vert;
+                        isVertical |= feature == vrt2;
+                        isVertical |= feature == vrtr;
+                    }
+
                     GlyphMetrics metrics = fontMetrics.GetGlyphMetrics(codePoint, id, textAttributes, textDecorations, layoutMode, colorFontSupport);
                     {
                         // If the glyphs are fallbacks we don't want them as
@@ -183,16 +197,20 @@ public bool TryUpdate(Font font, GlyphSubstitutionCollection collection)
                         }
                     }
 
-                    if (!hasFallBacks)
+                    if (metrics.GlyphType != GlyphType.Fallback)
                     {
                         if (j == 0)
                         {
                             // There should only be a single fallback glyph at this position from the previous collection.
                             this.glyphs.RemoveAt(i);
                         }
 
+                        // We only want a single dimensional advance for positioning.
+                        GlyphShapingBounds bounds = isVertical
+                            ? new(0, 0, 0, metrics.AdvanceHeight)
+                            : new(0, 0, metrics.AdvanceWidth, 0);
+
                         // Track the number of inserted glyphs at the offset so we can correctly increment our position.
-                        GlyphShapingBounds bounds = new(0, 0, metrics.AdvanceWidth, metrics.AdvanceHeight);
                         this.glyphs.Insert(i += replacementCount, new(offset, new(shape, true) { Bounds = bounds }, pointSize, metrics.CloneForRendering(shape.TextRun)));
                         replacementCount++;
                     }
@@ -259,6 +277,7 @@ public bool TryAdd(Font font, GlyphSubstitutionCollection collection)
                 hasFallBacks = true;
             }
 
+            // We only want a single dimensional advance for positioning.
             GlyphShapingBounds bounds = isVertical
                 ? new(0, 0, 0, metrics.AdvanceHeight)
                 : new(0, 0, metrics.AdvanceWidth, 0);

src/SixLabors.Fonts/Tables/AdvancedTypographic/GPosTable.cs

@@ -125,7 +125,13 @@ public bool TryUpdatePositions(FontMetrics fontMetrics, GlyphPositioningCollecti
                 // We want to assign the same feature lookups to individual sections of the text rather
                 // than the text as a whole to ensure that different language shapers do not interfere
                 // with each other when the text contains multiple languages.
-                GlyphShapingData nextData = collection[i + 1];
+                int ni = i + 1;
+                GlyphShapingData nextData = collection[ni];
+                if (!collection.ShouldProcess(fontMetrics, ni))
+                {
+                    break;
+                }
+
                 ScriptClass next = CodePoint.GetScriptClass(nextData.CodePoint);
                 if (next != current &&
                     current is not ScriptClass.Common and not ScriptClass.Unknown and not ScriptClass.Inherited &&

src/SixLabors.Fonts/Tables/General/HorizontalMetricsTable.cs

@@ -19,7 +19,10 @@ public ushort GetAdvancedWidth(int glyphIndex)
     {
         if (glyphIndex >= this.advancedWidths.Length)
         {
-            return this.advancedWidths[0];
+            // Records are indexed by glyph ID. As an optimization, the number of records can
+            // be less than the number of glyphs, in which case the advance width value of the
+            // last record applies to all remaining glyph IDs.
+            return this.advancedWidths[^1];
         }
 
         return this.advancedWidths[glyphIndex];
@@ -29,7 +32,7 @@ internal short GetLeftSideBearing(int glyphIndex)
     {
         if (glyphIndex >= this.leftSideBearings.Length)
         {
-            return this.leftSideBearings[0];
+            return this.leftSideBearings[^1];
         }
 
         return this.leftSideBearings[glyphIndex];

tests/SixLabors.Fonts.Tests/Issues/Issues_469.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Six Labors.
+// Licensed under the Six Labors Split License.
+
+using System.Text;
+
+namespace SixLabors.Fonts.Tests.Issues;
+
+public class Issues_469
+{
+    [Fact]
+    public void Test_Issue_469()
+    {
+        const string arialFontName = "Arial";
+        const string inconsolataFontName = "Inconsolata";
+        const string nanumGothicCodingFontName = "NanumGothicCoding";
+        const string cousineFontName = "Cousine";
+        const string notoSansScThinFontName = "Noto Sans SC Thin";
+        const string notoSansJpThinFontName = "Noto Sans JP Thin";
+        const string notoNaskhArabicFontName = "Noto Naskh Arabic";
+        const string sarabunFontName = "Sarabun";
+        const string hindFontName = "Hind";
+
+        StringBuilder stringBuilder = new();
+        stringBuilder.AppendLine("Latin: The quick brown fox jumps over the lazy dog.")
+            .AppendLine("Cyrillic: Съешь же ещё этих мягких французских булок.")
+            .AppendLine("Greek: Ζαφείρι δέξου πάγκαλο, βαθῶν ψυχῆς τὸ σῆμα.")
+            .AppendLine("Chinese: 敏捷的棕色狐狸跳过了懒狗")
+            .AppendLine("Japanese: いろはにほへと ちりぬるを")
+            .AppendLine("Korean: 다람쥐 헌 쳇바퀴에 타고파")
+            .AppendLine("Arabic (RTL & Shaping): نص حكيم له سر قاطع وذو شأن عظيم")
+            .AppendLine("Hebrew (RTL): דג סקרן שט בים מאוכזב ולפתע מצא חברה")
+            .AppendLine("Thai (Complex): เป็นมนุษย์สุดประเสริฐเลิศคุณค่า")
+            .AppendLine("Devanagari (Conjuncts): ऋषियों को सताने वाले राक्षसों का अंत हो गया");
+
+        string text = stringBuilder.ToString();
+        FontCollection fontCollection = new();
+        fontCollection.Add(TestFonts.Arial);
+        fontCollection.Add(TestFonts.CousineRegular);
+        fontCollection.Add(TestFonts.HindRegular);
+        fontCollection.Add(TestFonts.NanumGothicCodingRegular);
+        fontCollection.Add(TestFonts.InconsolataRegular);
+        fontCollection.Add(TestFonts.NotoNaskhArabicRegular);
+        fontCollection.Add(TestFonts.NotoSansHKVariableFontWght);
+        fontCollection.Add(TestFonts.NotoSansJPRegular);
+        fontCollection.Add(TestFonts.NotoSansSCRegular);
+        fontCollection.Add(TestFonts.SarabunRegular);
+
+        FontFamily mainFontFamily = fontCollection.Get(arialFontName);
+        Font mainFont = mainFontFamily.CreateFont(30, FontStyle.Regular);
+
+        TextOptions options = new(mainFont)
+        {
+            FallbackFontFamilies =
+            [
+                fontCollection.Get(inconsolataFontName),
+                fontCollection.Get(nanumGothicCodingFontName),
+                fontCollection.Get(cousineFontName),
+                fontCollection.Get(notoSansScThinFontName),
+                fontCollection.Get(notoSansJpThinFontName),
+                fontCollection.Get(notoNaskhArabicFontName),
+                fontCollection.Get(sarabunFontName),
+                fontCollection.Get(hindFontName),
+            ],
+        };
+
+        // There are too many metrics to validate here so we just ensure no exceptions are thrown
+        // and the rendering looks correct by inspecting the snapshot.
+        TextLayoutTestUtilities.TestLayout(
+            text,
+            options,
+            includeGeometry: false);
+    }
+}

tests/SixLabors.Fonts.Tests/SixLabors.Fonts.Tests.csproj

@@ -3,7 +3,6 @@
   <PropertyGroup>
     <DebugSymbols>True</DebugSymbols>
     <Platforms>AnyCPU;x64;x86</Platforms>
-    <LangVersion>10</LangVersion>
   </PropertyGroup>
 
   <PropertyGroup>
@@ -29,8 +28,8 @@
     Comment out this constant declaration to disable all tests based upon image generation.
     This allows us to make breaking changes to the Fonts API without breaking the tests.
     -->
-    <!--<DefineConstants>$(DefineConstants);SUPPORTS_DRAWING</DefineConstants>
-    <HasSupportForDrawing Condition="$(DefineConstants.Contains('SUPPORTS_DRAWING'))">true</HasSupportForDrawing>-->
+    <DefineConstants>$(DefineConstants);SUPPORTS_DRAWING</DefineConstants>
+    <HasSupportForDrawing Condition="$(DefineConstants.Contains('SUPPORTS_DRAWING'))">true</HasSupportForDrawing>
   </PropertyGroup>
 
   <ItemGroup Condition="$(HasSupportForDrawing) != true">
@@ -48,7 +47,7 @@
   </ItemGroup>
 
   <ItemGroup>
-    <!--<PackageReference Include="SixLabors.ImageSharp.Drawing" Version="2.1.4" Condition="$(HasSupportForDrawing)" />-->
+    <PackageReference Include="SixLabors.ImageSharp.Drawing" Version="3.0.0-alpha.0.6" />
     <PackageReference Include="Pegasus" Version="4.1.0" PrivateAssets="all" />
     <Compile Include="..\..\src\UnicodeTrieGenerator\StateAutomation\DeterministicFiniteAutomata.cs" Link="Unicode\StateAutomation\DeterministicFiniteAutomata.cs" />
     <Compile Include="..\..\src\UnicodeTrieGenerator\StateAutomation\Compile.cs" Link="Unicode\StateAutomation\Compile.cs" />

tests/SixLabors.Fonts.Tests/TestFonts.cs

@@ -265,6 +265,26 @@
 
     public static string NotoColorEmojiRegular => GetFullPath("NotoColorEmoji-Regular.ttf");
 
+    public static string Arial => GetFullPath("arial.ttf");
+
+    public static string CousineRegular => GetFullPath("Cousine-Regular.ttf");
+
+    public static string HindRegular => GetFullPath("Hind-Regular.ttf");
+
+    public static string NanumGothicCodingRegular => GetFullPath("NanumGothicCoding-Regular.ttf");
+
+    public static string InconsolataRegular => GetFullPath("Inconsolata-Regular.ttf");
+
+    public static string NotoNaskhArabicRegular => GetFullPath("NotoNaskhArabic-Regular.ttf");
+
+    public static string NotoSansHKVariableFontWght => GetFullPath("NotoSansHK-VariableFont_wght.ttf");
+
+    public static string NotoSansJPRegular => GetFullPath("NotoSansJP-Regular.ttf");
+
+    public static string NotoSansSCRegular => GetFullPath("NotoSansSC-Regular.ttf");
+
+    public static string SarabunRegular => GetFullPath("Sarabun-Regular.ttf");
+
     public static Stream TwemojiMozillaData() => OpenStream(TwemojiMozillaFile);
 
     public static Stream SegoeuiEmojiData() => OpenStream(SegoeuiEmojiFile);
@@ -314,9 +334,9 @@
         return ms;
     }
 
-    private static string GetFullPath(string path)
+    public static string GetFullPath(string path)
     {
         string root = Path.GetDirectoryName(new Uri(typeof(TestFonts).GetTypeInfo().Assembly.CodeBase).LocalPath);
 
         string[] paths = new[]
         {

tests/SixLabors.Fonts.Tests/TextLayoutTestUtilities.cs

@@ -7,9 +7,8 @@
 using SixLabors.Fonts.Tables.AdvancedTypographic;
 using SixLabors.Fonts.Tests.TestUtilities;
 using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.Drawing;
 using SixLabors.ImageSharp.Drawing.Processing;
-using SixLabors.ImageSharp.Drawing.Shapes.Text;
+using SixLabors.ImageSharp.Drawing.Text;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 #endif
@@ -74,7 +73,7 @@ public static void TestLayout(
         extended.Insert(0, "G");
         using Image<Rgba32> img2 = new(Configuration.Default, imageWidth, imageHeight, Color.White.ToPixel<Rgba32>());
 
-        IReadOnlyList<GlyphPathCollection> glyphs = TextBuilder.GenerateGlyphs2(text, options);
+        IReadOnlyList<GlyphPathCollection> glyphs = TextBuilder.GenerateGlyphs(text, options);
 
         img2.Mutate(ctx => ctx.Fill(Color.Black, glyphs));