Merge pull request #329 from SixLabors/advanced-pixel-reference

Expose advanced pixel reference API.

src/ImageSharp/Advanced/ImageExtensions.cs → src/ImageSharp/Advanced/AdvancedImageExtensions.cs

@@ -10,15 +10,39 @@ namespace SixLabors.ImageSharp.Advanced
     /// <summary>
     /// Extension methods over Image{TPixel}
     /// </summary>
-    internal static class ImageExtensions
+    public static class AdvancedImageExtensions
     {
+        /// <summary>
+        /// Returns a reference to the 0th element of the Pixel buffer,
+        /// allowing direct manipulation of pixel data through unsafe operations.
+        /// The pixel buffer is a contigous memory area containing Width*Height TPixel elements layed out in row-major order.
+        /// </summary>
+        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <param name="source">The source image frame</param>
+        /// <returns>A pinnable reference the first root of the pixel buffer.</returns>
+        public static ref TPixel DangerousGetPinnableReferenceToPixelBuffer<TPixel>(this ImageFrame<TPixel> source)
+            where TPixel : struct, IPixel<TPixel>
+         => ref DangerousGetPinnableReferenceToPixelBuffer((IPixelSource<TPixel>)source);
+
+        /// <summary>
+        /// Returns a reference to the 0th element of the Pixel buffer,
+        /// allowing direct manipulation of pixel data through unsafe operations.
+        /// The pixel buffer is a contigous memory area containing Width*Height TPixel elements layed out in row-major order.
+        /// </summary>
+        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <param name="source">The source image</param>
+        /// <returns>A pinnable reference the first root of the pixel buffer.</returns>
+        public static ref TPixel DangerousGetPinnableReferenceToPixelBuffer<TPixel>(this Image<TPixel> source)
+            where TPixel : struct, IPixel<TPixel>
+         => ref source.Frames.RootFrame.DangerousGetPinnableReferenceToPixelBuffer();
+
         /// <summary>
         /// Gets the representation of the pixels as an area of contiguous memory in the given pixel format.
         /// </summary>
         /// <typeparam name="TPixel">The type of the pixel.</typeparam>
         /// <param name="source">The source.</param>
         /// <returns>The <see cref="Span{TPixel}"/></returns>
-        public static Span<TPixel> GetPixelSpan<TPixel>(this ImageFrame<TPixel> source)
+        internal static Span<TPixel> GetPixelSpan<TPixel>(this ImageFrame<TPixel> source)
             where TPixel : struct, IPixel<TPixel>
             => GetSpan(source);
 
@@ -29,7 +53,7 @@ namespace SixLabors.ImageSharp.Advanced
         /// <param name="source">The source.</param>
         /// <param name="row">The row.</param>
         /// <returns>The <see cref="Span{TPixel}"/></returns>
-        public static Span<TPixel> GetPixelRowSpan<TPixel>(this ImageFrame<TPixel> source, int row)
+        internal static Span<TPixel> GetPixelRowSpan<TPixel>(this ImageFrame<TPixel> source, int row)
             where TPixel : struct, IPixel<TPixel>
             => GetSpan(source, row);
 
@@ -39,7 +63,7 @@ namespace SixLabors.ImageSharp.Advanced
         /// <typeparam name="TPixel">The type of the pixel.</typeparam>
         /// <param name="source">The source.</param>
         /// <returns>The <see cref="Span{TPixel}"/></returns>
-        public static Span<TPixel> GetPixelSpan<TPixel>(this Image<TPixel> source)
+        internal static Span<TPixel> GetPixelSpan<TPixel>(this Image<TPixel> source)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.GetPixelSpan();
 
@@ -50,7 +74,7 @@ namespace SixLabors.ImageSharp.Advanced
         /// <param name="source">The source.</param>
         /// <param name="row">The row.</param>
         /// <returns>The <see cref="Span{TPixel}"/></returns>
-        public static Span<TPixel> GetPixelRowSpan<TPixel>(this Image<TPixel> source, int row)
+        internal static Span<TPixel> GetPixelRowSpan<TPixel>(this Image<TPixel> source, int row)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.GetPixelRowSpan(row);
 
@@ -60,7 +84,7 @@ namespace SixLabors.ImageSharp.Advanced
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <returns>Returns the configuration.</returns>
-        public static Configuration GetConfiguration<TPixel>(this Image<TPixel> source)
+        internal static Configuration GetConfiguration<TPixel>(this Image<TPixel> source)
             where TPixel : struct, IPixel<TPixel>
             => GetConfiguration((IConfigurable)source);
 
@@ -107,5 +131,15 @@ namespace SixLabors.ImageSharp.Advanced
         /// <returns>Returns the bounds of the image</returns>
         private static Configuration GetConfiguration(IConfigurable source)
             => source?.Configuration ?? Configuration.Default;
+
+        /// <summary>
+        /// Returns a reference to the 0th element of the Pixel buffer.
+        /// Such a reference can be used for pinning but must never be dereferenced.
+        /// </summary>
+        /// <param name="source">The source image frame</param>
+        /// <returns>A reference to the element.</returns>
+        private static ref TPixel DangerousGetPinnableReferenceToPixelBuffer<TPixel>(IPixelSource<TPixel> source)
+            where TPixel : struct, IPixel<TPixel>
+            => ref source.PixelBuffer.Span.DangerousGetPinnableReference();
     }
 }

src/ImageSharp/Common/Extensions/SimdUtils.cs

@@ -17,11 +17,11 @@ namespace SixLabors.ImageSharp
         /// <summary>
         /// Indicates AVX2 architecture where both float and integer registers are of size 256 byte.
         /// </summary>
-        public static readonly bool IsAvx2 = Vector<float>.Count == 8 && Vector<int>.Count == 8;
+        public static readonly bool IsAvx2CompatibleArchitecture = Vector<float>.Count == 8 && Vector<int>.Count == 8;
 
         internal static void GuardAvx2(string operation)
         {
-            if (!IsAvx2)
+            if (!IsAvx2CompatibleArchitecture)
             {
                 throw new NotSupportedException($"{operation} is supported only on AVX2 CPU!");
             }

src/ImageSharp/Image/ImageExtensions.cs

@@ -112,7 +112,7 @@ namespace SixLabors.ImageSharp
         }
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        ///  Saves the raw image pixels to a byte array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
@@ -123,7 +123,7 @@ namespace SixLabors.ImageSharp
          => source.GetPixelSpan().AsBytes().ToArray();
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Saves the raw image pixels to the given byte array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
@@ -131,26 +131,21 @@ namespace SixLabors.ImageSharp
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
         public static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, byte[] buffer)
             where TPixel : struct, IPixel<TPixel>
-            => SavePixelData(source, new Span<byte>(buffer));
+            => SavePixelData(source, buffer.AsSpan().NonPortableCast<byte, TPixel>());
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Saves the raw image pixels to the given TPixel array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
-        private static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, Span<byte> buffer)
+        public static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, TPixel[] buffer)
             where TPixel : struct, IPixel<TPixel>
-        {
+            => SavePixelData(source, new Span<TPixel>(buffer));
-            Span<byte> byteBuffer = source.GetPixelSpan().AsBytes();
-            Guard.MustBeGreaterThanOrEqualTo(buffer.Length, byteBuffer.Length, nameof(buffer));
-
-            byteBuffer.CopyTo(buffer);
-        }
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Saves the raw image pixels to a byte array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
@@ -161,7 +156,7 @@ namespace SixLabors.ImageSharp
          => source.Frames.RootFrame.SavePixelData();
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Saves the raw image pixels to the given byte array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
@@ -172,13 +167,13 @@ namespace SixLabors.ImageSharp
             => source.Frames.RootFrame.SavePixelData(buffer);
 
         /// <summary>
-        /// Saves the raw image to the given bytes.
+        /// Saves the raw image pixels to the given TPixel array in row-major order.
         /// </summary>
         /// <typeparam name="TPixel">The Pixel format.</typeparam>
         /// <param name="source">The source image</param>
         /// <param name="buffer">The buffer to save the raw pixel data to.</param>
         /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
-        private static void SavePixelData<TPixel>(this Image<TPixel> source, Span<byte> buffer)
+        public static void SavePixelData<TPixel>(this Image<TPixel> source, TPixel[] buffer)
             where TPixel : struct, IPixel<TPixel>
             => source.Frames.RootFrame.SavePixelData(buffer);
 
@@ -200,5 +195,32 @@ namespace SixLabors.ImageSharp
                 return $"data:{format.DefaultMimeType};base64,{Convert.ToBase64String(stream.ToArray())}";
             }
         }
+
+        /// <summary>
+        /// Saves the raw image to the given bytes.
+        /// </summary>
+        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <param name="source">The source image</param>
+        /// <param name="buffer">The buffer to save the raw pixel data to.</param>
+        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        internal static void SavePixelData<TPixel>(this Image<TPixel> source, Span<byte> buffer)
+            where TPixel : struct, IPixel<TPixel>
+            => source.Frames.RootFrame.SavePixelData(buffer.NonPortableCast<byte, TPixel>());
+
+        /// <summary>
+        /// Saves the raw image to the given bytes.
+        /// </summary>
+        /// <typeparam name="TPixel">The Pixel format.</typeparam>
+        /// <param name="source">The source image</param>
+        /// <param name="buffer">The buffer to save the raw pixel data to.</param>
+        /// <exception cref="System.ArgumentNullException">Thrown if the stream is null.</exception>
+        internal static void SavePixelData<TPixel>(this ImageFrame<TPixel> source, Span<TPixel> buffer)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            Span<TPixel> sourceBuffer = source.GetPixelSpan();
+            Guard.MustBeGreaterThanOrEqualTo(buffer.Length, sourceBuffer.Length, nameof(buffer));
+
+            sourceBuffer.CopyTo(buffer);
+        }
     }
 }

src/ImageSharp/PixelFormats/Rgba32.PixelOperations.cs

@@ -120,7 +120,7 @@ namespace SixLabors.ImageSharp
             {
                 GuardSpans(sourceVectors, nameof(sourceVectors), destColors, nameof(destColors), count);
 
-                if (!SimdUtils.IsAvx2)
+                if (!SimdUtils.IsAvx2CompatibleArchitecture)
                 {
                     base.PackFromVector4(sourceVectors, destColors, count);
                     return;

tests/ImageSharp.Tests/Advanced/AdvancedImageExtensionsTests.cs

@@ -0,0 +1,38 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using Xunit;
+using SixLabors.ImageSharp.Advanced;
+using System.Runtime.CompilerServices;
+// ReSharper disable InconsistentNaming
+
+namespace SixLabors.ImageSharp.Tests.Advanced
+{
+    using SixLabors.ImageSharp.PixelFormats;
+
+    public class AdvancedImageExtensionsTests
+    {
+        [Theory]
+        [WithTestPatternImages(131, 127, PixelTypes.Rgba32 | PixelTypes.Bgr24)]
+        public unsafe void DangerousGetPinnableReference_CopyToBuffer<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            using (Image<TPixel> image = provider.GetImage())
+            {
+                TPixel[] targetBuffer = new TPixel[image.Width * image.Height];
+
+                ref byte source = ref Unsafe.As<TPixel, byte>(ref targetBuffer[0]);
+                ref byte dest = ref Unsafe.As<TPixel, byte>(ref image.DangerousGetPinnableReferenceToPixelBuffer());
+                
+                fixed (byte* targetPtr = &source)
+                fixed (byte* pixelBasePtr = &dest)
+                {
+                    uint dataSizeInBytes = (uint)(image.Width * image.Height * Unsafe.SizeOf<TPixel>());
+                    Unsafe.CopyBlock(targetPtr, pixelBasePtr, dataSizeInBytes);
+                }
+
+                image.ComparePixelBufferTo(targetBuffer);
+            }
+        }
+    }
+}

tests/ImageSharp.Tests/Common/SimdUtilsTests.cs

@@ -109,6 +109,16 @@ namespace SixLabors.ImageSharp.Tests.Common
             AssertEvenRoundIsCorrect(r, v);
         }
 
+        private bool SkipOnNonAvx2([CallerMemberName] string testCaseName = null)
+        {
+            if (!SimdUtils.IsAvx2CompatibleArchitecture)
+            {
+                this.Output.WriteLine("Skipping AVX2 specific test case: " + testCaseName);
+                return true;
+            }
+            return false;
+        }
+
         [Theory]
         [InlineData(1, 0)]
         [InlineData(1, 8)]
@@ -116,6 +126,11 @@ namespace SixLabors.ImageSharp.Tests.Common
         [InlineData(3, 128)]
         public void BulkConvertNormalizedFloatToByte_WithRoundedData(int seed, int count)
         {
+            if (this.SkipOnNonAvx2())
+            {
+                return;
+            }
+
             float[] orig =  new Random(seed).GenerateRandomRoundedFloatArray(count, 0, 256);
             float[] normalized = orig.Select(f => f / 255f).ToArray();
 
@@ -135,6 +150,11 @@ namespace SixLabors.ImageSharp.Tests.Common
         [InlineData(3, 128)]
         public void BulkConvertNormalizedFloatToByte_WithNonRoundedData(int seed, int count)
         {
+            if (this.SkipOnNonAvx2())
+            {
+                return;
+            }
+
             float[] source = new Random(seed).GenerateRandomFloatArray(count, 0, 1f);
             
             byte[] dest = new byte[count];
@@ -155,6 +175,11 @@ namespace SixLabors.ImageSharp.Tests.Common
         [InlineData(3, 128)]
         public void BulkConvertNormalizedFloatToByteClampOverflows(int seed, int count)
         {
+            if (this.SkipOnNonAvx2())
+            {
+                return;
+            }
+
             float[] orig = new Random(seed).GenerateRandomRoundedFloatArray(count, -50, 444);
             float[] normalized = orig.Select(f => f / 255f).ToArray();
 
@@ -185,6 +210,11 @@ namespace SixLabors.ImageSharp.Tests.Common
         [Fact]
         private void BulkConvertNormalizedFloatToByte_Step()
         {
+            if (this.SkipOnNonAvx2())
+            {
+                return;
+            }
+
             float[] source = {0, 7, 42, 255, 0.5f, 1.1f, 2.6f, 16f};
             byte[] expected = source.Select(f => (byte)Math.Round(f)).ToArray();
 

tests/ImageSharp.Tests/Image/ImageSaveTests.cs

@@ -9,9 +9,12 @@ using SixLabors.ImageSharp.IO;
 using SixLabors.ImageSharp.PixelFormats;
 using Moq;
 using Xunit;
+// ReSharper disable InconsistentNaming
 
 namespace SixLabors.ImageSharp.Tests
 {
+    using System.Runtime.CompilerServices;
+
     /// <summary>
     /// Tests the <see cref="Image"/> class.
     /// </summary>
@@ -47,76 +50,39 @@ namespace SixLabors.ImageSharp.Tests
             this.Image = new Image<Rgba32>(config, 1, 1);
         }
 
-        [Fact]
+        [Theory]
-        public void SavePixelData_Rgba32()
+        [WithTestPatternImages(13, 19, PixelTypes.Rgba32 | PixelTypes.Bgr24)]
+        public void SavePixelData_ToPixelStructArray<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
         {
-            using (var img = new Image<Rgba32>(2, 2))
+            using (Image<TPixel> image = provider.GetImage())
             {
-                img[0, 0] = Rgba32.White;
+                TPixel[] buffer = new TPixel[image.Width*image.Height];
-                img[1, 0] = Rgba32.Black;
+                image.SavePixelData(buffer);
 
-                img[0, 1] = Rgba32.Red;
+                image.ComparePixelBufferTo(buffer);
-                img[1, 1] = Rgba32.Blue;
+
-                var buffer = new byte[2 * 2 * 4]; // width * height * bytes per pixel
+                // TODO: We need a separate test-case somewhere ensuring that image pixels are stored in row-major order!
-                img.SavePixelData(buffer);
-
-                Assert.Equal(255, buffer[0]); // 0, 0, R
-                Assert.Equal(255, buffer[1]); // 0, 0, G
-                Assert.Equal(255, buffer[2]); // 0, 0, B
-                Assert.Equal(255, buffer[3]); // 0, 0, A
-
-                Assert.Equal(0, buffer[4]); // 1, 0, R
-                Assert.Equal(0, buffer[5]); // 1, 0, G
-                Assert.Equal(0, buffer[6]); // 1, 0, B
-                Assert.Equal(255, buffer[7]); // 1, 0, A
-
-                Assert.Equal(255, buffer[8]); // 0, 1, R
-                Assert.Equal(0, buffer[9]); // 0, 1, G
-                Assert.Equal(0, buffer[10]); // 0, 1, B
-                Assert.Equal(255, buffer[11]); // 0, 1, A
-
-                Assert.Equal(0, buffer[12]); // 1, 1, R
-                Assert.Equal(0, buffer[13]); // 1, 1, G
-                Assert.Equal(255, buffer[14]); // 1, 1, B
-                Assert.Equal(255, buffer[15]); // 1, 1, A
             }
         }
 
-
+        [Theory]
-        [Fact]
+        [WithTestPatternImages(19, 13, PixelTypes.Rgba32 | PixelTypes.Bgr24)]
-        public void SavePixelData_Bgr24()
+        public void SavePixelData_ToByteArray<TPixel>(TestImageProvider<TPixel> provider)
+            where TPixel : struct, IPixel<TPixel>
         {
-            using (var img = new Image<Bgr24>(2, 2))
+            using (Image<TPixel> image = provider.GetImage())
             {
-                img[0, 0] = NamedColors<Bgr24>.White;
+                byte[] buffer = new byte[image.Width*image.Height*Unsafe.SizeOf<TPixel>()];
-                img[1, 0] = NamedColors<Bgr24>.Black;
-
-                img[0, 1] = NamedColors<Bgr24>.Red;
-                img[1, 1] = NamedColors<Bgr24>.Blue;
-
-                var buffer = new byte[2 * 2 * 3]; // width * height * bytes per pixel
-                img.SavePixelData(buffer);
 
-                Assert.Equal(255, buffer[0]); // 0, 0, B
+                image.SavePixelData(buffer);
-                Assert.Equal(255, buffer[1]); // 0, 0, G
-                Assert.Equal(255, buffer[2]); // 0, 0, R
 
-                Assert.Equal(0, buffer[3]); // 1, 0, B
+                image.ComparePixelBufferTo(buffer.AsSpan().NonPortableCast<byte, TPixel>());
-                Assert.Equal(0, buffer[4]); // 1, 0, G
-                Assert.Equal(0, buffer[5]); // 1, 0, R
-
-                Assert.Equal(0, buffer[6]); // 0, 1, B
-                Assert.Equal(0, buffer[7]); // 0, 1,   G
-                Assert.Equal(255, buffer[8]); // 0, 1,  R
-
-                Assert.Equal(255, buffer[9]); // 1, 1,  B
-                Assert.Equal(0, buffer[10]); // 1, 1,  G
-                Assert.Equal(0, buffer[11]); // 1, 1, R
             }
         }
-
+        
         [Fact]
-        public void SavePixelData_Rgba32_Buffer_must_be_bigger()
+        public void SavePixelData_Rgba32_WhenBufferIsTooSmall_Throws()
         {
             using (var img = new Image<Rgba32>(2, 2))
             {

tests/ImageSharp.Tests/TestUtilities/TestImageExtensions.cs

@@ -17,6 +17,8 @@ namespace SixLabors.ImageSharp.Tests
     using SixLabors.ImageSharp.Advanced;
     using SixLabors.ImageSharp.Memory;
 
+    using Xunit;
+
     public static class TestImageExtensions
     {
         /// <summary>
@@ -81,7 +83,7 @@ namespace SixLabors.ImageSharp.Tests
                 grayscale,
                 appendPixelTypeToFileName);
         }
-
+        
         /// <summary>
         /// Compares the image against the expected Reference output, throws an exception if the images are not similar enough.
         /// The output file should be named identically to the output produced by <see cref="DebugSave{TPixel}(Image{TPixel}, ITestImageProvider, object, string, bool)"/>.
@@ -153,6 +155,24 @@ namespace SixLabors.ImageSharp.Tests
             }
         }
 
+        public static Image<TPixel> ComparePixelBufferTo<TPixel>(
+            this Image<TPixel> image,
+            Span<TPixel> expectedPixels)
+            where TPixel : struct, IPixel<TPixel>
+        {
+            Span<TPixel> actual = image.GetPixelSpan();
+
+            Assert.True(expectedPixels.Length == actual.Length, "Buffer sizes are not equal!");
+
+            for (int i = 0; i < expectedPixels.Length; i++)
+            {
+                Assert.True(expectedPixels[i].Equals(actual[i]), $"Pixels are different on position {i}!" );
+            }
+            
+            return image;
+        }
+
+
         public static Image<TPixel> CompareToOriginal<TPixel>(
             this Image<TPixel> image,
             ITestImageProvider provider)
@@ -160,7 +180,7 @@ namespace SixLabors.ImageSharp.Tests
         {
             return CompareToOriginal(image, provider, ImageComparer.Tolerant());
         }
-
+        
         public static Image<TPixel> CompareToOriginal<TPixel>(
             this Image<TPixel> image,
             ITestImageProvider provider,