From 9ffcc51ed6b72f557d804f6393b0a610c673c703 Mon Sep 17 00:00:00 2001
From: Anton Firszov <antonfir@gmail.com>
Date: Tue, 15 Feb 2022 02:19:35 +0100
Subject: [PATCH] Respect PreferContiguousImageBuffers in decoders

---
 .../Decoder/SpectralConverter{TPixel}.cs      |  5 ++-
 src/ImageSharp/Image.Decode.cs                |  6 ++-
 .../Image/LargeImageIntegrationTests.cs       | 37 ++++++++++++++++++-
 3 files changed, 44 insertions(+), 4 deletions(-)

diff --git a/src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs b/src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs
index 40411ef288..430adeb21d 100644
--- a/src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs
+++ b/src/ImageSharp/Formats/Jpeg/Components/Decoder/SpectralConverter{TPixel}.cs
@@ -111,7 +111,10 @@ namespace SixLabors.ImageSharp.Formats.Jpeg.Components.Decoder
             this.pixelRowsPerStep = majorVerticalSamplingFactor * blockPixelHeight;
 
             // pixel buffer for resulting image
-            this.pixelBuffer = allocator.Allocate2D<TPixel>(frame.PixelWidth, frame.PixelHeight);
+            this.pixelBuffer = allocator.Allocate2D<TPixel>(
+                frame.PixelWidth,
+                frame.PixelHeight,
+                this.configuration.PreferContiguousImageBuffers);
             this.paddedProxyPixelRow = allocator.Allocate<TPixel>(frame.PixelWidth + 3);
 
             // component processors from spectral to Rgba32
diff --git a/src/ImageSharp/Image.Decode.cs b/src/ImageSharp/Image.Decode.cs
index ee340bf86e..c892b82ba8 100644
--- a/src/ImageSharp/Image.Decode.cs
+++ b/src/ImageSharp/Image.Decode.cs
@@ -37,8 +37,10 @@ namespace SixLabors.ImageSharp
             ImageMetadata metadata)
             where TPixel : unmanaged, IPixel<TPixel>
         {
-            Buffer2D<TPixel> uninitializedMemoryBuffer =
-                configuration.MemoryAllocator.Allocate2D<TPixel>(width, height);
+            Buffer2D<TPixel> uninitializedMemoryBuffer = configuration.MemoryAllocator.Allocate2D<TPixel>(
+                    width,
+                    height,
+                    configuration.PreferContiguousImageBuffers);
             return new Image<TPixel>(configuration, uninitializedMemoryBuffer.FastMemoryGroup, width, height, metadata);
         }
 
diff --git a/tests/ImageSharp.Tests/Image/LargeImageIntegrationTests.cs b/tests/ImageSharp.Tests/Image/LargeImageIntegrationTests.cs
index b2ee9d673e..00714c816a 100644
--- a/tests/ImageSharp.Tests/Image/LargeImageIntegrationTests.cs
+++ b/tests/ImageSharp.Tests/Image/LargeImageIntegrationTests.cs
@@ -2,7 +2,10 @@
 // Licensed under the Apache License, Version 2.0.
 
 using System;
+using System.IO;
 using Microsoft.DotNet.RemoteExecutor;
+using SixLabors.ImageSharp.Advanced;
+using SixLabors.ImageSharp.Formats;
 using SixLabors.ImageSharp.Memory;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
@@ -32,12 +35,44 @@ namespace SixLabors.ImageSharp.Tests
                 Configuration configuration = Configuration.Default.Clone();
                 configuration.PreferContiguousImageBuffers = true;
 
-                using var image = new Image<Rgba32>(configuration, 8192, 4096);
+                using var image = new Image<Rgba32>(configuration, 2048, 2048);
                 Assert.True(image.DangerousTryGetSinglePixelMemory(out Memory<Rgba32> mem));
                 Assert.Equal(8192 * 4096, mem.Length);
             }
         }
 
+        [Theory]
+        [InlineData("bmp")]
+        [InlineData("png")]
+        [InlineData("jpeg")]
+        [InlineData("gif")]
+        [InlineData("tiff")]
+        [InlineData("webp")]
+        public void PreferContiguousImageBuffers_LoadImage_BufferIsContiguous(string formatOuter)
+        {
+            // Run remotely to avoid large allocation in the test process:
+            // RemoteExecutor.Invoke(RunTest).Dispose();
+            RunTest(formatOuter);
+
+            static void RunTest(string formatInner)
+            {
+                Configuration configuration = Configuration.Default.Clone();
+                configuration.PreferContiguousImageBuffers = true;
+                IImageEncoder encoder = configuration.ImageFormatsManager.FindEncoder(
+                    configuration.ImageFormatsManager.FindFormatByFileExtension(formatInner));
+                string dir = TestEnvironment.CreateOutputDirectory(".Temp");
+                string path = Path.Combine(dir, $"{Guid.NewGuid().ToString()}.{formatInner}");
+                using (Image<Rgba32> temp = new(2048, 2048))
+                {
+                    temp.Save(path, encoder);
+                }
+
+                using var image = Image.Load<Rgba32>(configuration, path);
+                File.Delete(path);
+                Assert.Equal(1, image.GetPixelMemoryGroup().Count);
+            }
+        }
+
         [Theory]
         [WithBasicTestPatternImages(width: 10, height: 10, PixelTypes.Rgba32)]
         public void DangerousTryGetSinglePixelMemory_WhenImageTooLarge_ReturnsFalse(TestImageProvider<Rgba32> provider)