robust ResizeKernelMap calculations using TolerantMath

src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeKernelMap.PeriodicKernelMap.cs

@@ -63,7 +63,7 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 for (int i = startOfFirstRepeatedMosaic; i < bottomStartDest; i++)
                 {
                     double center = ((i + .5) * this.ratio) - .5;
-                    int left = (int)Math.Ceiling(center - this.radius);
+                    int left = (int)TolerantMath.Ceiling(center - this.radius);
                     ResizeKernel kernel = this.kernels[i - this.period];
                     this.kernels[i] = kernel.AlterLeftValue(left);
                 }

src/ImageSharp/Processing/Processors/Transforms/Resize/ResizeKernelMap.cs

@@ -17,6 +17,8 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
     /// </summary>
     internal partial class ResizeKernelMap : IDisposable
     {
+        private static readonly TolerantMath TolerantMath = TolerantMath.Default;
+
         private readonly IResampler sampler;
 
         private readonly int sourceLength;
@@ -107,15 +109,14 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
                 scale = 1F;
             }
 
-            int radius = (int)Math.Ceiling(scale * sampler.Radius);
+            int radius = (int)TolerantMath.Ceiling(scale * sampler.Radius);
             int period = ImageMaths.LeastCommonMultiple(sourceSize, destinationSize) / sourceSize;
-            double center0 = (ratio - 1) * 0.5f;
+            double center0 = (ratio - 1) * 0.5;
             double firstNonNegativeLeftVal = (radius - center0 - 1) / ratio;
-            int cornerInterval = (int)Math.Ceiling(firstNonNegativeLeftVal);
+            int cornerInterval = (int)TolerantMath.Ceiling(firstNonNegativeLeftVal);
 
             // corner case for cornerInteval:
-            // TODO: Implement library-wide utils for tolerant comparison
-            if (Math.Abs(firstNonNegativeLeftVal - cornerInterval) < 1e-8)
+            if (TolerantMath.AreEqual(firstNonNegativeLeftVal, cornerInterval))
             {
                 cornerInterval++;
             }
@@ -167,13 +168,13 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
             double center = ((destRowIndex + .5) * this.ratio) - .5;
 
             // Keep inside bounds.
-            int left = (int)Math.Ceiling(center - this.radius);
+            int left = (int)TolerantMath.Ceiling(center - this.radius);
             if (left < 0)
             {
                 left = 0;
             }
 
-            int right = (int)Math.Floor(center + this.radius);
+            int right = (int)TolerantMath.Floor(center + this.radius);
             if (right > this.sourceLength - 1)
             {
                 right = this.sourceLength - 1;

tests/ImageSharp.Tests/ImageSharp.Tests.csproj

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

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

@@ -35,27 +35,29 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
                     scale = 1F;
                 }
 
-                double radius = (double)Math.Ceiling(scale * sampler.Radius);
+                TolerantMath tolerantMath = TolerantMath.Default;
+
+                double radius = tolerantMath.Ceiling(scale * sampler.Radius);
                 
                 var result = new List<ReferenceKernel>();
 
                 for (int i = 0; i < destinationSize; i++)
                 {
-                    if (i == 21 || i == 64)
-                    {
-                        Debug.Print("lol");
-                    }
+                    //if (i == 21 || i == 64)
+                    //{
+                    //    Debug.Print("lol");
+                    //}
 
                     double center = ((i + .5) * ratio) - .5;
 
                     // Keep inside bounds.
-                    int left = (int)Math.Ceiling(center - radius);
+                    int left = (int)tolerantMath.Ceiling(center - radius);
                     if (left < 0)
                     {
                         left = 0;
                     }
 
-                    int right = (int)Math.Floor(center + radius);
+                    int right = (int)tolerantMath.Floor(center + radius);
                     if (right > sourceSize - 1)
                     {
                         right = sourceSize - 1;

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

@@ -119,7 +119,6 @@ namespace SixLabors.ImageSharp.Tests.Processing.Processors.Transforms
         }
 #endif
 
-
         private void VerifyKernelMapContentIsCorrect(string resamplerName, int srcSize, int destSize)
         {
             IResampler resampler = TestUtils.GetResampler(resamplerName);