add benchmark project

src/Oh.My.Stitcher.Benchmark/Oh.My.Stitcher.Benchmark.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="BenchmarkDotNet" Version="0.15.2" />
+    <PackageReference Include="NSubstitute" Version="5.3.0" />
+  </ItemGroup>
+
+  <ItemGroup>
+    <ProjectReference Include="..\Oh.My.Stitcher\Oh.My.Stitcher.csproj" />
+  </ItemGroup>
+
+</Project>

src/Oh.My.Stitcher.Benchmark/OperationBenchmark.cs

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+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Jobs;
+using NetVips;
+using Oh.My.Stitcher.NetVips;
+
+namespace Oh.My.Stitcher.Benchmark;
+
+[SimpleJob(RuntimeMoniker.Net80)]
+[MemoryDiagnoser]
+public class OperationBenchmark
+{
+  // CHANGE ME
+  private const string TILES_DIRECTORY = "/home/formulatrix/Downloads/tiles1705";
+
+  [Benchmark(Baseline = true)] // Mark this as the baseline for comparison
+  public void Standard_Operation()
+  {
+    const string rect = "A1:AE55";
+    if( !Tile.TryParseRect(rect, out int minRow, out int maxRow, out int minCol, out int maxCol) )
+      throw new ArgumentException($"Invalid canvas_rect: '{rect}'");
+
+    for( int row = minRow; row <= maxRow; row++ )
+    for( int col = minCol; col <= maxCol; col++ )
+    {
+      string path = Tile.FullPath(TILES_DIRECTORY, row, col);
+      using var i = ( Operation.Call("pngload", path) as Image )!;
+    }
+  }
+
+  [Benchmark]
+  public void Fast_Operation()
+  {
+    const string rect = "A1:AE55";
+    if( !Tile.TryParseRect(rect, out int minRow, out int maxRow, out int minCol, out int maxCol) )
+      throw new ArgumentException($"Invalid canvas_rect: '{rect}'");
+
+    Span<byte> pathBuffer = stackalloc byte[512];
+    for( int row = minRow; row <= maxRow; row++ )
+    for( int col = minCol; col <= maxCol; col++ )
+    {
+      int length = Tile.FullPathFast(TILES_DIRECTORY, row, col, pathBuffer);
+      using var i = ( OperationHacks.Call("pngload", pathBuffer.Slice(0, length + 1)) as Image )!;
+    }
+  }
+}

src/Oh.My.Stitcher.Benchmark/PathCreationBenchmark.cs

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+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Jobs;
+
+namespace Oh.My.Stitcher.Benchmark;
+
+[SimpleJob(RuntimeMoniker.Net80)]
+[MemoryDiagnoser]
+public class PathCreationBenchmark
+{
+  // CHANGE ME
+  private const string TILES_DIRECTORY = "/home/formulatrix/Downloads/tiles1705";
+
+  [Benchmark(Baseline = true)] // Mark this as the baseline for comparison
+  public void Standard_PathCombine()
+  {
+    const string rect = "A1:AE55";
+    if( !Tile.TryParseRect(rect, out int minRow, out int maxRow, out int minCol, out int maxCol) )
+      throw new ArgumentException($"Invalid canvas_rect: '{rect}'");
+
+    for( int row = minRow; row <= maxRow; row++ )
+    for( int col = minCol; col <= maxCol; col++ )
+    {
+      Tile.FullPath(TILES_DIRECTORY, row, col);
+    }
+  }
+
+  [Benchmark]
+  public void Fast_PathCombine()
+  {
+    const string rect = "A1:AE55";
+    if( !Tile.TryParseRect(rect, out int minRow, out int maxRow, out int minCol, out int maxCol) )
+      throw new ArgumentException($"Invalid canvas_rect: '{rect}'");
+
+    Span<byte> pathBuffer = stackalloc byte[512];
+    for( int row = minRow; row <= maxRow; row++ )
+    for( int col = minCol; col <= maxCol; col++ )
+    {
+      Tile.FullPathFast(TILES_DIRECTORY, row, col, pathBuffer);
+    }
+  }
+}

src/Oh.My.Stitcher.Benchmark/Program.cs

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+using BenchmarkDotNet.Running;
+
+namespace Oh.My.Stitcher.Benchmark;
+
+static class Program
+{
+  static void Main(string[] _)
+  {
+    BenchmarkRunner.Run<PathCreationBenchmark>();
+    BenchmarkRunner.Run<OperationBenchmark>();
+    BenchmarkRunner.Run<UsageBenchmark>();
+  }
+}

src/Oh.My.Stitcher.Benchmark/UsageBenchmark.cs

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+using BenchmarkDotNet.Attributes;
+using BenchmarkDotNet.Jobs;
+using Microsoft.Extensions.Caching.Memory;
+using Microsoft.Extensions.Logging;
+using NetVips;
+using NSubstitute;
+
+namespace Oh.My.Stitcher.Benchmark;
+
+[SimpleJob(RuntimeMoniker.Net80)]
+[MemoryDiagnoser]
+public class UsageBenchmark
+{
+  // CHANGE ME
+  private const string TILES_DIRECTORY = "/home/formulatrix/Downloads/tiles1705";
+
+  [Benchmark(Baseline = true)] // Mark this as the baseline for comparison
+  public void Standard_Usage()
+  {
+    Stitch request = new()
+    {
+      CanvasRect = "A1:AE55", CropOffset = new CropOffset(0, 0), CropSize = new CropSize(1, 1), OutputScale = 1
+    };
+    Image? image = null;
+    List<Image> images = [];
+    IMemoryCache cache = Substitute.For<IMemoryCache>();
+    ILogger logger = Substitute.For<ILogger>();
+    try
+    {
+      Tile.TryCreate(in request, TILES_DIRECTORY, images, logger, cache, out image, out string? _, out string? _);
+    }
+    finally
+    {
+      image?.Dispose();
+      foreach( Image img in images )
+        img.Dispose();
+    }
+  }
+
+  [Benchmark]
+  public void Fast_Usage()
+  {
+    Stitch request = new()
+    {
+      CanvasRect = "A1:AE55", CropOffset = new CropOffset(0, 0), CropSize = new CropSize(1, 1), OutputScale = 1
+    };
+    Image? image = null;
+    List<Image> images = [];
+    IMemoryCache cache = Substitute.For<IMemoryCache>();
+    ILogger logger = Substitute.For<ILogger>();
+    try
+    {
+      Tile.TryCreateFast(in request, TILES_DIRECTORY, images, logger, cache, out image, out string? _, out string? _);
+    }
+    finally
+    {
+      image?.Dispose();
+      foreach( Image img in images )
+        img.Dispose();
+    }
+  }
+}