Implement retained stroke rasterization and stroke commands

Author: JimBobSquarePants

ImageSharp.Drawing.sln

@@ -346,8 +346,6 @@ Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "WebGPUWindowDemo", "samples
 EndProject
 Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ImageSharp.Drawing.WebGPU.ShaderGen", "src\ImageSharp.Drawing.WebGPU.ShaderGen\ImageSharp.Drawing.WebGPU.ShaderGen.csproj", "{C7606104-5D58-4670-912C-3F336606B02D}"
 EndProject
-Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "ImageSharp", "..\ImageSharp\src\ImageSharp\ImageSharp.csproj", "{FE71764E-E7BD-B378-8A4C-86929A28AD25}"
-EndProject
 Global
 	GlobalSection(SolutionConfigurationPlatforms) = preSolution
 		Debug|Any CPU = Debug|Any CPU
@@ -454,18 +452,6 @@ Global
 		{C7606104-5D58-4670-912C-3F336606B02D}.Release|x64.Build.0 = Release|Any CPU
 		{C7606104-5D58-4670-912C-3F336606B02D}.Release|x86.ActiveCfg = Release|Any CPU
 		{C7606104-5D58-4670-912C-3F336606B02D}.Release|x86.Build.0 = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|Any CPU.Build.0 = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|x64.ActiveCfg = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|x64.Build.0 = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|x86.ActiveCfg = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Debug|x86.Build.0 = Debug|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|Any CPU.ActiveCfg = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|Any CPU.Build.0 = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|x64.ActiveCfg = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|x64.Build.0 = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|x86.ActiveCfg = Release|Any CPU
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25}.Release|x86.Build.0 = Release|Any CPU
 	EndGlobalSection
 	GlobalSection(SolutionProperties) = preSolution
 		HideSolutionNode = FALSE
@@ -497,7 +483,6 @@ Global
 		{061582C2-658F-40AE-A978-7D74A4EB2C0A} = {815C0625-CD3D-440F-9F80-2D83856AB7AE}
 		{2541FDCD-78AC-40DB-B5E3-6A715DC132BA} = {528610AC-7C0C-46E8-9A2D-D46FD92FEE29}
 		{C7606104-5D58-4670-912C-3F336606B02D} = {815C0625-CD3D-440F-9F80-2D83856AB7AE}
-		{FE71764E-E7BD-B378-8A4C-86929A28AD25} = {815C0625-CD3D-440F-9F80-2D83856AB7AE}
 	EndGlobalSection
 	GlobalSection(ExtensibilityGlobals) = postSolution
 		SolutionGuid = {5F8B9D1F-CD8B-4CC5-8216-D531E25BD795}
@@ -506,7 +491,6 @@ Global
 		shared-infrastructure\src\SharedInfrastructure\SharedInfrastructure.projitems*{061582c2-658f-40ae-a978-7d74a4eb2c0a}*SharedItemsImports = 5
 		shared-infrastructure\src\SharedInfrastructure\SharedInfrastructure.projitems*{2e33181e-6e28-4662-a801-e2e7dc206029}*SharedItemsImports = 5
 		shared-infrastructure\src\SharedInfrastructure\SharedInfrastructure.projitems*{68a8cc40-6aed-4e96-b524-31b1158fdeea}*SharedItemsImports = 13
-		..\ImageSharp\shared-infrastructure\src\SharedInfrastructure\SharedInfrastructure.projitems*{fe71764e-e7bd-b378-8a4c-86929a28ad25}*SharedItemsImports = 5
 	EndGlobalSection
 	GlobalSection(Performance) = preSolution
 		HasPerformanceSessions = true

samples/WebGPUWindowDemo/Program.cs

@@ -28,7 +28,7 @@ public static unsafe class Program
 {
     private const int WindowWidth = 800;
     private const int WindowHeight = 600;
-    private const int BallCount = 500;
+    private const int BallCount = 1000;
 
     // Silk.NET WebGPU API and windowing handles.
     private static WebGPU wgpu;

src/ImageSharp.Drawing.WebGPU/WebGPUSceneEncoder.cs

@@ -273,6 +273,13 @@ internal bool TryBuild(CompositionScene scene, out string? error)
                         return false;
                     }
                 }
+                else if (command is StrokePathCompositionSceneCommand strokePathCommand)
+                {
+                    if (!this.TryAppend(strokePathCommand.Command, out error))
+                    {
+                        return false;
+                    }
+                }
                 else if (command is LineSegmentCompositionSceneCommand lineSegmentCommand)
                 {
                     if (!this.TryAppend(lineSegmentCommand.Command, out error))
@@ -294,7 +301,7 @@ internal bool TryBuild(CompositionScene scene, out string? error)
         }
 
         /// <summary>
-        /// Appends one prepared path- or layer-based command to the scene streams when the command kind is supported.
+        /// Appends one prepared fill-path or layer-based command to the scene streams when the command kind is supported.
         /// </summary>
         private bool TryAppend(in CompositionCommand command, out string? error)
         {
@@ -314,13 +321,6 @@ private bool TryAppend(in CompositionCommand command, out string? error)
 
                     this.AppendTransformIfChanged(command.Transform);
 
-                    if (command.Pen is Pen pen)
-                    {
-                        this.AppendPlainStroke(resolved, pen);
-                        error = null;
-                        return true;
-                    }
-
                     this.AppendPlainFill(resolved);
                     error = null;
                     return true;
@@ -340,6 +340,28 @@ private bool TryAppend(in CompositionCommand command, out string? error)
             return true;
         }
 
+        /// <summary>
+        /// Appends one prepared stroked path command to the scene streams.
+        /// </summary>
+        private bool TryAppend(in StrokePathCommand command, out string? error)
+        {
+            if (!TryResolveCommand(command, out ResolvedPathCommand resolved))
+            {
+                error = null;
+                return true;
+            }
+
+            if (!this.TryRegisterVisibleFill(resolved.Brush, resolved.RasterizerOptions, out error))
+            {
+                return false;
+            }
+
+            this.AppendTransformIfChanged(command.Transform);
+            this.AppendPlainStroke(resolved, command.Pen);
+            error = null;
+            return true;
+        }
+
         /// <summary>
         /// Appends one prepared explicit line-segment stroke to the scene streams.
         /// </summary>
@@ -933,6 +955,18 @@ private static bool TryResolveCommand(in CompositionCommand command, out Resolve
         return true;
     }
 
+    private static bool TryResolveCommand(in StrokePathCommand command, out ResolvedPathCommand resolved)
+    {
+        resolved = new ResolvedPathCommand(
+            command.SourcePath,
+            command.Brush,
+            command.GraphicsOptions,
+            command.RasterizerOptions,
+            command.DestinationOffset,
+            command.Brush is ImageBrush ? command.RasterizerOptions.Interest : default);
+        return true;
+    }
+
     private static bool TryResolveCommand(in StrokeLineSegmentCommand command, out ResolvedLineSegmentCommand resolved)
     {
         resolved = new ResolvedLineSegmentCommand(
@@ -1173,10 +1207,6 @@ private static int EncodeStrokePath(
         for (int i = 0; i < geometry.Contours.Count; i++)
         {
             LinearContour contour = geometry.Contours[i];
-            if (contour.SegmentCount == 0)
-            {
-                continue;
-            }
 
             int markerWordCount = contour.IsClosed ? 2 : 4;
             Span<uint> contourData = pathData.GetAppendSpan(2 + (contour.SegmentCount * 2) + markerWordCount);
@@ -1454,10 +1484,6 @@ private static int EstimateStrokeLineCount(LinearGeometry geometry, Pen pen)
         for (int i = 0; i < geometry.Contours.Count; i++)
         {
             LinearContour contour = geometry.Contours[i];
-            if (contour.SegmentCount == 0)
-            {
-                continue;
-            }
 
             total += contour.SegmentCount * 2;
             if (contour.IsClosed)

src/ImageSharp.Drawing/ImageSharp.Drawing.csproj

@@ -45,19 +45,10 @@
     <None Include="..\..\shared-infrastructure\branding\icons\imagesharp.drawing\sixlabors.imagesharp.drawing.128.png" Pack="true" PackagePath="" />
   </ItemGroup>
   <ItemGroup>
-    <PackageReference Include="SixLabors.Fonts" Version="3.0.0-alpha.0.31" />
-    <!--<PackageReference Include="SixLabors.ImageSharp" Version="4.0.0-alpha.0.86" />-->
+    <PackageReference Include="SixLabors.Fonts" Version="3.0.0-alpha.0.36" />
+    <PackageReference Include="SixLabors.ImageSharp" Version="4.0.0-alpha.0.88" />
     <PackageReference Include="SixLabors.PolygonClipper" Version="1.0.0-alpha.0.52" />
   </ItemGroup>
-  <ItemGroup>
-    <ProjectReference Include="..\..\..\ImageSharp\src\ImageSharp\ImageSharp.csproj" />
-  </ItemGroup>
-
-  <ItemGroup>
-    <Using Include="SixLabors.ImageSharp" />
-    <Using Include="SixLabors.ImageSharp.PixelFormats" />
-    <Using Include="SixLabors.ImageSharp.Processing" />
-  </ItemGroup>
 
   <Import Project="..\..\shared-infrastructure\src\SharedInfrastructure\SharedInfrastructure.projitems" Label="Shared" />
 

src/ImageSharp.Drawing/LinearGeometry.cs

@@ -26,6 +26,9 @@ namespace SixLabors.ImageSharp.Drawing;
 /// </remarks>
 public sealed class LinearGeometry
 {
+    private readonly LinearContour[] contours;
+    private readonly PointF[] points;
+
     /// <summary>
     /// Initializes a new instance of the <see cref="LinearGeometry"/> class.
     /// </summary>
@@ -34,9 +37,14 @@ public sealed class LinearGeometry
     /// <param name="points">The point storage.</param>
     public LinearGeometry(LinearGeometryInfo info, IReadOnlyList<LinearContour> contours, IReadOnlyList<PointF> points)
     {
+        ArgumentNullException.ThrowIfNull(contours);
+        ArgumentNullException.ThrowIfNull(points);
+
         this.Info = info;
-        this.Contours = contours ?? throw new ArgumentNullException(nameof(contours));
-        this.Points = points ?? throw new ArgumentNullException(nameof(points));
+        this.contours = contours as LinearContour[] ?? [.. contours];
+        this.points = points as PointF[] ?? [.. points];
+        this.Contours = this.contours;
+        this.Points = this.points;
     }
 
     /// <summary>
@@ -61,14 +69,10 @@ public LinearGeometry(LinearGeometryInfo info, IReadOnlyList<LinearContour> cont
     /// </remarks>
     public IReadOnlyList<PointF> Points { get; }
 
-    /// <summary>
-    /// Creates retained geometry for one open two-point polyline.
-    /// </summary>
-    /// <param name="start">The first point.</param>
-    /// <param name="end">The second point.</param>
-    /// <returns>The retained open polyline geometry.</returns>
-    public static LinearGeometry CreateOpenPolyline(PointF start, PointF end)
-        => CreateOpenPolyline([start, end]);
+    internal ReadOnlySpan<LinearContour> GetContours() => this.contours;
+
+    internal ReadOnlySpan<PointF> GetContourPoints(in LinearContour contour)
+        => this.points.AsSpan(contour.PointStart, contour.PointCount);
 
     /// <summary>
     /// Creates retained geometry for one open polyline.

src/ImageSharp.Drawing/Processing/Backends/CompositionCommand.cs

@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Drawing.Processing.Backends;
 public enum CompositionCommandKind : byte
 {
     /// <summary>
-    /// A fill or stroked-path command.
+    /// A fill-path command.
     /// </summary>
     FillLayer = 0,
 
@@ -27,14 +27,13 @@ public enum CompositionCommandKind : byte
 }
 
 /// <summary>
-/// One normalized path- or layer-based composition command queued by <see cref="DrawingCanvasBatcher{TPixel}"/>.
+/// One normalized fill-path or layer-based composition command queued by <see cref="DrawingCanvasBatcher{TPixel}"/>.
 /// </summary>
 /// <remarks>
-/// This type carries path-backed draw commands plus inline layer boundaries.
+/// This type carries fill-path commands plus inline layer boundaries.
 /// </remarks>
 public readonly struct CompositionCommand
 {
-    private readonly Pen? pen;
     private readonly IPath? sourcePath;
     private readonly Brush? brush;
     private readonly Matrix4x4 transform;
@@ -50,7 +49,6 @@ private CompositionCommand(
         Rectangle targetBounds,
         Rectangle layerBounds,
         Point destinationOffset,
-        Pen? pen,
         Matrix4x4 transform,
         IReadOnlyList<IPath>? clipPaths,
         ShapeOptions? shapeOptions)
@@ -63,7 +61,6 @@ private CompositionCommand(
         this.TargetBounds = targetBounds;
         this.LayerBounds = layerBounds;
         this.DestinationOffset = destinationOffset;
-        this.pen = pen;
         this.transform = transform;
         this.clipPaths = clipPaths;
         this.shapeOptions = shapeOptions;
@@ -74,11 +71,6 @@ private CompositionCommand(
     /// </summary>
     public CompositionCommandKind Kind { get; }
 
-    /// <summary>
-    /// Gets the stroke metadata for stroke commands.
-    /// </summary>
-    public readonly Pen? Pen => this.pen;
-
     /// <summary>
     /// Gets the absolute bounds of the logical target for this command.
     /// </summary>
@@ -134,7 +126,7 @@ private CompositionCommand(
     public ShapeOptions ShapeOptions => this.shapeOptions ?? throw new InvalidOperationException("Layer commands do not carry shape options.");
 
     /// <summary>
-    /// Creates a path-backed composition command.
+    /// Creates a fill-path composition command.
     /// </summary>
     /// <param name="path">Path in target-local coordinates.</param>
     /// <param name="brush">Brush used during composition.</param>
@@ -144,7 +136,6 @@ private CompositionCommand(
     /// <param name="transform">Transform matrix supplied with the command.</param>
     /// <param name="targetBounds">The absolute bounds of the logical target for this command.</param>
     /// <param name="destinationOffset">Absolute destination offset where coverage is composited.</param>
-    /// <param name="pen">Optional pen for stroked-path commands.</param>
     /// <param name="clipPaths">Optional clip paths supplied with the command.</param>
     /// <returns>The composition command.</returns>
     public static CompositionCommand Create(
@@ -156,7 +147,6 @@ public static CompositionCommand Create(
         Matrix4x4 transform,
         Rectangle targetBounds,
         Point destinationOffset = default,
-        Pen? pen = null,
         IReadOnlyList<IPath>? clipPaths = null)
         => new(
             CompositionCommandKind.FillLayer,
@@ -167,7 +157,6 @@ public static CompositionCommand Create(
             targetBounds,
             default,
             destinationOffset,
-            pen,
             transform,
             clipPaths,
             shapeOptions);
@@ -188,7 +177,6 @@ public static CompositionCommand CreateBeginLayer(Rectangle layerBounds, Graphic
             layerBounds,
             layerBounds,
             default,
-            null,
             Matrix4x4.Identity,
             null,
             null);
@@ -209,7 +197,6 @@ public static CompositionCommand CreateEndLayer(Rectangle layerBounds, GraphicsO
             layerBounds,
             layerBounds,
             default,
-            null,
             Matrix4x4.Identity,
             null,
             null);

src/ImageSharp.Drawing/Processing/Backends/CompositionSceneCommandBase.cs

@@ -11,11 +11,17 @@ namespace SixLabors.ImageSharp.Drawing.Processing.Backends;
 public interface ICompositionSceneCommandVisitor
 {
     /// <summary>
-    /// Visits one path- or layer-based composition command.
+    /// Visits one fill-path or layer-based composition command.
     /// </summary>
     /// <param name="command">The command being visited.</param>
     public void Visit(PathCompositionSceneCommand command);
 
+    /// <summary>
+    /// Visits one stroked path command.
+    /// </summary>
+    /// <param name="command">The command being visited.</param>
+    public void Visit(StrokePathCompositionSceneCommand command);
+
     /// <summary>
     /// Visits one explicit stroked line-segment command.
     /// </summary>
@@ -42,7 +48,7 @@ public abstract class CompositionSceneCommand
 }
 
 /// <summary>
-/// Scene command wrapper for path- and layer-based composition commands.
+/// Scene command wrapper for fill-path and layer-based composition commands.
 /// </summary>
 public sealed class PathCompositionSceneCommand : CompositionSceneCommand
 {
@@ -62,6 +68,27 @@ public PathCompositionSceneCommand(in CompositionCommand command)
     public override void Accept(ICompositionSceneCommandVisitor visitor) => visitor.Visit(this);
 }
 
+/// <summary>
+/// Scene command wrapper for stroked path commands.
+/// </summary>
+public sealed class StrokePathCompositionSceneCommand : CompositionSceneCommand
+{
+    /// <summary>
+    /// Initializes a new instance of the <see cref="StrokePathCompositionSceneCommand"/> class.
+    /// </summary>
+    /// <param name="command">The wrapped stroke path command.</param>
+    public StrokePathCompositionSceneCommand(in StrokePathCommand command)
+        => this.Command = command;
+
+    /// <summary>
+    /// Gets the wrapped stroke path command.
+    /// </summary>
+    public StrokePathCommand Command { get; internal set; }
+
+    /// <inheritdoc />
+    public override void Accept(ICompositionSceneCommandVisitor visitor) => visitor.Visit(this);
+}
+
 /// <summary>
 /// Scene command wrapper for explicit stroked line-segment commands.
 /// </summary>

src/ImageSharp.Drawing/Processing/Backends/DefaultRasterizer.Linearizer.cs

@@ -144,7 +144,7 @@ protected Linearizer(
         /// Executes the linearization pass and finalizes the retained row payloads.
         /// </summary>
         /// <returns><see langword="true"/> when any retained coverage was produced; otherwise <see langword="false"/>.</returns>
-        protected bool ProcessCore()
+        protected virtual bool ProcessCore()
         {
             RectangleF translatedBounds = this.Geometry.Info.Bounds;
             translatedBounds.Offset(this.TranslateX + this.SamplingOffsetX - this.MinX, this.TranslateY + this.SamplingOffsetY - this.MinY);