Add test for #2259

src/ImageSharp/Image.FromStream.cs

@@ -517,6 +517,7 @@ public abstract partial class Image
     /// <param name="stream">The input stream.</param>
     /// <param name="action">The action to perform.</param>
     /// <returns>The <typeparamref name="T"/>.</returns>
+    /// <exception cref="NotSupportedException">Cannot read from the stream.</exception>
     internal static T WithSeekableStream<T>(
         DecoderOptions options,
         Stream stream,

tests/ImageSharp.Tests/Formats/GeneralFormatTests.cs

@@ -46,6 +46,21 @@ public class GeneralFormatTests
         image.DebugSave(provider);
     }
 
+    [Fact]
+    public void ReadOriginIsRespectedOnLoad()
+    {
+        using FileStream stream = File.OpenRead(TestFile.GetInputFileFullPath(TestImages.Png.Issue2259));
+        using Image<Rgb24> i = Image.Load<Rgb24>(stream);
+        long position1 = stream.Position;
+        Assert.NotEqual(0, position1);
+
+        using Image<Rgb24> j = Image.Load<Rgb24>(stream);
+        long position2 = stream.Position;
+        Assert.True(position2 > position1);
+
+        Assert.NotEqual(i[5, 5], j[5, 5]);
+    }
+
     [Fact]
     public void ImageCanEncodeToString()
     {
@@ -155,15 +170,15 @@ public class GeneralFormatTests
         foreach (TestFile file in Files)
         {
             byte[] serialized;
-            using (var image = Image.Load(file.Bytes, out IImageFormat mimeType))
-            using (var memoryStream = new MemoryStream())
+            using (Image image = Image.Load(file.Bytes, out IImageFormat mimeType))
+            using (MemoryStream memoryStream = new())
             {
                 image.Save(memoryStream, mimeType);
                 memoryStream.Flush();
                 serialized = memoryStream.ToArray();
             }
 
-            using var image2 = Image.Load<Rgba32>(serialized);
+            using Image<Rgba32> image2 = Image.Load<Rgba32>(serialized);
             image2.Save($"{path}{Path.DirectorySeparatorChar}{file.FileName}");
         }
     }
@@ -198,8 +213,8 @@ public class GeneralFormatTests
 
     public void CanIdentifyImageLoadedFromBytes(int width, int height, string extension)
     {
-        using var image = Image.LoadPixelData<Rgba32>(new Rgba32[width * height], width, height);
-        using var memoryStream = new MemoryStream();
+        using Image<Rgba32> image = Image.LoadPixelData<Rgba32>(new Rgba32[width * height], width, height);
+        using MemoryStream memoryStream = new();
         IImageFormat format = GetFormat(extension);
         image.Save(memoryStream, format);
         memoryStream.Position = 0;
@@ -220,7 +235,7 @@ public class GeneralFormatTests
     {
         byte[] invalid = new byte[10];
 
-        using var memoryStream = new MemoryStream(invalid);
+        using MemoryStream memoryStream = new(invalid);
         IImageInfo imageInfo = Image.Identify(memoryStream, out IImageFormat format);
 
         Assert.Null(imageInfo);

tests/ImageSharp.Tests/TestImages.cs

@@ -130,6 +130,9 @@ public static class TestImages
         // Issue 2209: https://github.com/SixLabors/ImageSharp/issues/2209
         public const string Issue2209IndexedWithTransparency = "Png/issues/Issue_2209.png";
 
+        // Issue 2259: https://github.com/SixLabors/ImageSharp/issues/2259
+        public const string Issue2259 = "Png/issues/Issue_2259.png";
+
         public static class Bad
         {
             public const string MissingDataChunk = "Png/xdtn0g01.png";

tests/Images/Input/Png/issues/Issue_2259.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:45b635fe3104e96b7c6d8fa9d28f7fb86fb184c7a407c44a2f90f3f88c140ef0
+size 6037