ParseStream -only benchmark

tests/ImageSharp.Benchmarks/Codecs/Jpeg/DecodeJpegParseStreamOnly.cs

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+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using BenchmarkDotNet.Attributes;
+using System.Drawing;
+using System.IO;
+using SixLabors.ImageSharp.Formats.Jpeg;
+using SixLabors.ImageSharp.Formats.Jpeg.PdfJsPort;
+using SixLabors.ImageSharp.Tests;
+
+namespace SixLabors.ImageSharp.Benchmarks.Codecs.Jpeg
+{
+    [Config(typeof(Config.ShortClr))]
+    public class DecodeJpegParseStreamOnly
+    {
+        [Params(TestImages.Jpeg.Baseline.Jpeg420Exif)]
+        public string TestImage { get; set; }
+
+        private string TestImageFullPath => Path.Combine(TestEnvironment.InputImagesDirectoryFullPath, this.TestImage);
+
+        private byte[] jpegBytes;
+
+        [GlobalSetup]
+        public void Setup()
+        {
+            this.jpegBytes = File.ReadAllBytes(this.TestImageFullPath);
+        }
+
+        [Benchmark(Baseline = true, Description = "System.Drawing FULL")]
+        public Size JpegSystemDrawing()
+        {
+            using (var memoryStream = new MemoryStream(this.jpegBytes))
+            {
+                using (var image = System.Drawing.Image.FromStream(memoryStream))
+                {
+                    return image.Size;
+                }
+            }
+        }
+
+        [Benchmark(Description = "PdfJsJpegDecoderCore.ParseStream")]
+        public void ParseStreamPdfJs()
+        {
+            using (var memoryStream = new MemoryStream(this.jpegBytes))
+            {
+                var decoder = new PdfJsJpegDecoderCore(Configuration.Default, new JpegDecoder() { IgnoreMetadata = true });
+                decoder.ParseStream(memoryStream);
+                decoder.Dispose();
+            }
+        }
+    }
+}