KernelMap refactor WIP

src/ImageSharp.Drawing/ImageSharp.Drawing.csproj

@@ -5,7 +5,8 @@
         <VersionPrefix Condition="$(packageversion) != ''">$(packageversion)</VersionPrefix>
         <VersionPrefix Condition="$(packageversion) == ''">0.0.1</VersionPrefix>
         <Authors>SixLabors and contributors</Authors>
-        <TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>
+        <!--<TargetFrameworks>netstandard1.3;netstandard2.0</TargetFrameworks>-->
+        <TargetFramework>netcoreapp2.1</TargetFramework>
         <LangVersion>7.3</LangVersion>
         <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
         <GenerateDocumentationFile>true</GenerateDocumentationFile>

src/ImageSharp/ImageSharp.csproj

@@ -5,7 +5,8 @@
     <VersionPrefix Condition="$(packageversion) != ''">$(packageversion)</VersionPrefix>
     <VersionPrefix Condition="$(packageversion) == ''">0.0.1</VersionPrefix>
     <Authors>Six Labors and contributors</Authors>
-    <TargetFrameworks>netstandard1.3;netstandard2.0;netcoreapp2.1;net472</TargetFrameworks>
+    <!--<TargetFrameworks>netstandard1.3;netstandard2.0;netcoreapp2.1;net472</TargetFrameworks>-->
+    <TargetFramework>netcoreapp2.1</TargetFramework>
     <AllowUnsafeBlocks>true</AllowUnsafeBlocks>
     <GenerateDocumentationFile>true</GenerateDocumentationFile>
     <AssemblyName>SixLabors.ImageSharp</AssemblyName>

src/ImageSharp/Processing/Processors/Transforms/KernelMap.cs

@@ -19,16 +19,23 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
 
         private readonly ResizeKernel[] kernels;
 
-        /// <summary>
-        /// Initializes a new instance of the <see cref="KernelMap"/> class.
-        /// </summary>
-        /// <param name="memoryAllocator">The <see cref="MemoryAllocator"/> to use for allocations.</param>
-        /// <param name="destinationSize">The size of the destination window</param>
-        /// <param name="kernelRadius">The radius of the kernel</param>
-        private KernelMap(MemoryAllocator memoryAllocator, int destinationSize, float kernelRadius)
+        private int period;
+
+        private int radius;
+
+        private int periodicRegionMin;
+
+        private int periodicRegionMax;
+
+        private KernelMap(MemoryAllocator memoryAllocator, int destinationSize, int radius, int period)
         {
             this.DestinationSize = destinationSize;
-            int width = (int)Math.Ceiling(kernelRadius * 2);
+            this.period = period;
+            this.radius = radius;
+            this.periodicRegionMin = period + radius;
+            this.periodicRegionMax = destinationSize - radius;
+
+            int width = radius * 2;
             this.data = memoryAllocator.Allocate2D<float>(width, destinationSize, AllocationOptions.Clean);
             this.kernels = new ResizeKernel[destinationSize];
         }
@@ -71,8 +78,10 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 scale = 1F;
             }
 
-            float radius = MathF.Ceiling(scale * sampler.Radius);
-            var result = new KernelMap(memoryAllocator, destinationSize, radius);
+            int period = ImageMaths.LeastCommonMultiple(sourceSize, destinationSize) / sourceSize;
+
+            int radius = (int)MathF.Ceiling(scale * sampler.Radius);
+            var result = new KernelMap(memoryAllocator, destinationSize, radius, period);
 
             for (int i = 0; i < destinationSize; i++)
             {
@@ -122,6 +131,11 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             return result;
         }
 
+        private int ReduceIndex(int destIndex)
+        {
+            return destIndex;
+        }
+
         /// <summary>
         /// Slices a weights value at the given positions.
         /// </summary>

tests/ImageSharp.Benchmarks/ImageSharp.Benchmarks.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>netcoreapp2.1;net461</TargetFrameworks>
+    <!--<TargetFrameworks>netcoreapp2.1;net461</TargetFrameworks>-->
+    <TargetFramework>netcoreapp2.1</TargetFramework>
     <OutputType>Exe</OutputType>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
     <RootNamespace>SixLabors.ImageSharp.Benchmarks</RootNamespace>

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

@@ -1,6 +1,7 @@
 <Project Sdk="Microsoft.NET.Sdk">
   <PropertyGroup>
-    <TargetFrameworks>net462;net472;netcoreapp2.1</TargetFrameworks>
+    <!--<TargetFrameworks>net462;net472;netcoreapp2.1</TargetFrameworks>-->
+    <TargetFramework>netcoreapp2.1</TargetFramework>
     <AllowUnsafeBlocks>True</AllowUnsafeBlocks>
     <LangVersion>latest</LangVersion>
     <DebugType Condition="$(codecov) != ''">full</DebugType>

tests/ImageSharp.Tests/Processing/Processors/Transforms/KernelMapTests.cs

@@ -20,17 +20,39 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
         {
             this.Output = output;
         }
-        
+
+        /// <summary>
+        /// resamplerName, srcSize, destSize
+        /// </summary>
+        public static readonly TheoryData<string, int, int> KernelMapData = new TheoryData<string, int, int>
+        {
+            { nameof(KnownResamplers.Bicubic), 15, 10 },
+            { nameof(KnownResamplers.Bicubic), 10, 15 },
+            { nameof(KnownResamplers.Bicubic), 20, 20 },
+            { nameof(KnownResamplers.Bicubic), 50, 40 },
+            { nameof(KnownResamplers.Bicubic), 40, 50 },
+            { nameof(KnownResamplers.Bicubic), 500, 200 },
+            { nameof(KnownResamplers.Bicubic), 200, 500 },
+
+            { nameof(KnownResamplers.Lanczos3), 16, 12 },
+            { nameof(KnownResamplers.Lanczos3), 12, 16 },
+            { nameof(KnownResamplers.Lanczos3), 12, 9 },
+            { nameof(KnownResamplers.Lanczos3), 9, 12 },
+            { nameof(KnownResamplers.Lanczos3), 6, 8 },
+            { nameof(KnownResamplers.Lanczos3), 8, 6 },
+
+            // TODO: What's wrong here:
+            // { nameof(KnownResamplers.Lanczos3), 20, 12 },
+
+            {nameof(KnownResamplers.Lanczos8), 500, 200 },
+            {nameof(KnownResamplers.Lanczos8), 100, 10 },
+            {nameof(KnownResamplers.Lanczos8), 100, 80 },
+            {nameof(KnownResamplers.Lanczos8), 10, 100 },
+        };
+
         [Theory]
-        [InlineData(500, 200, nameof(KnownResamplers.Bicubic))]
-        [InlineData(50, 40, nameof(KnownResamplers.Bicubic))]
-        [InlineData(40, 30, nameof(KnownResamplers.Bicubic))]
-        [InlineData(15, 10, nameof(KnownResamplers.Bicubic))]
-        [InlineData(500, 200, nameof(KnownResamplers.Lanczos8))]
-        [InlineData(100, 80, nameof(KnownResamplers.Lanczos8))]
-        [InlineData(100, 10, nameof(KnownResamplers.Lanczos8))]
-        [InlineData(10, 100, nameof(KnownResamplers.Lanczos8))]
-        public void KernelMapContentIsCorrect(int srcSize, int destSize, string resamplerName)
+        [MemberData(nameof(KernelMapData))]
+        public void KernelMapContentIsCorrect(string resamplerName, int srcSize, int destSize)
         {
             var resampler = (IResampler)typeof(KnownResamplers).GetProperty(resamplerName).GetValue(null);