Capture and throw degenerate matrices.

src/ImageSharp/Common/Exceptions/ImageProcessingException.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -8,8 +8,15 @@ namespace SixLabors.ImageSharp
     /// <summary>
     /// The exception that is thrown when an error occurs when applying a process to an image.
     /// </summary>
-    public sealed class ImageProcessingException : Exception
+    public class ImageProcessingException : Exception
     {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="ImageProcessingException"/> class.
+        /// </summary>
+        public ImageProcessingException()
+        {
+        }
+
         /// <summary>
         /// Initializes a new instance of the <see cref="ImageProcessingException"/> class with the name of the
         /// parameter that causes this exception.
@@ -32,4 +39,4 @@ namespace SixLabors.ImageSharp
         {
         }
     }
-}
+}

src/ImageSharp/Processing/AffineTransformBuilder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -284,6 +284,11 @@ namespace SixLabors.ImageSharp.Processing
                 matrix *= factory(size);
             }
 
+            if (TransformUtilities.IsNaN(matrix))
+            {
+                throw new DegenerateTransformException("Matrix is NaN. Check input values.");
+            }
+
             return matrix;
         }
 
@@ -299,4 +304,4 @@ namespace SixLabors.ImageSharp.Processing
             return this;
         }
     }
-}
+}

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

@@ -0,0 +1,42 @@
+// Copyright (c) Six Labors and contributors.
+// Licensed under the Apache License, Version 2.0.
+
+using System;
+
+namespace SixLabors.ImageSharp.Processing.Processors.Transforms
+{
+    /// <summary>
+    /// Represents an error that occurs during a transform operation.
+    /// </summary>
+    public sealed class DegenerateTransformException : ImageProcessingException
+    {
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DegenerateTransformException"/> class.
+        /// </summary>
+        public DegenerateTransformException()
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DegenerateTransformException" /> class
+        /// with a specified error message.
+        /// </summary>
+        /// <param name="message">The message that describes the error.</param>
+        public DegenerateTransformException(string message)
+            : base(message)
+        {
+        }
+
+        /// <summary>
+        /// Initializes a new instance of the <see cref="DegenerateTransformException" /> class
+        /// with a specified error message and a reference to the inner exception that is
+        /// the cause of this exception.
+        /// </summary>
+        /// <param name="message">The error message that explains the reason for the exception.</param>
+        /// <param name="innerException">The exception that is the cause of the current exception, or a null reference (<see langword="Nothing" /> in Visual Basic) if no inner exception is specified.</param>
+        public DegenerateTransformException(string message, Exception innerException)
+            : base(message, innerException)
+        {
+        }
+    }
+}

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

@@ -12,6 +12,35 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
     /// </summary>
     internal static class TransformUtilities
     {
+        /// <summary>
+        /// Returns a value that indicates whether the specified matrix contains any values
+        /// that are not a number <see cref="float.NaN"/>.
+        /// </summary>
+        /// <param name="matrix">The transform matrix.</param>
+        /// <returns>The <see cref="bool"/>.</returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public static bool IsNaN(Matrix3x2 matrix)
+        {
+            return float.IsNaN(matrix.M11) || float.IsNaN(matrix.M12)
+                || float.IsNaN(matrix.M21) || float.IsNaN(matrix.M22)
+                || float.IsNaN(matrix.M31) || float.IsNaN(matrix.M32);
+        }
+
+        /// <summary>
+        /// Returns a value that indicates whether the specified matrix contains any values
+        /// that are not a number <see cref="float.NaN"/>.
+        /// </summary>
+        /// <param name="matrix">The transform matrix.</param>
+        /// <returns>The <see cref="bool"/>.</returns>
+        [MethodImpl(InliningOptions.ShortMethod)]
+        public static bool IsNaN(Matrix4x4 matrix)
+        {
+            return float.IsNaN(matrix.M11) || float.IsNaN(matrix.M12) || float.IsNaN(matrix.M13) || float.IsNaN(matrix.M14)
+                || float.IsNaN(matrix.M21) || float.IsNaN(matrix.M22) || float.IsNaN(matrix.M23) || float.IsNaN(matrix.M24)
+                || float.IsNaN(matrix.M31) || float.IsNaN(matrix.M32) || float.IsNaN(matrix.M33) || float.IsNaN(matrix.M34)
+                || float.IsNaN(matrix.M41) || float.IsNaN(matrix.M42) || float.IsNaN(matrix.M43) || float.IsNaN(matrix.M44);
+        }
+
         /// <summary>
         /// Applies the projective transform against the given coordinates flattened into the 2D space.
         /// </summary>

src/ImageSharp/Processing/ProjectiveTransformBuilder.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -300,6 +300,11 @@ namespace SixLabors.ImageSharp.Processing
                 matrix *= factory(size);
             }
 
+            if (TransformUtilities.IsNaN(matrix))
+            {
+                throw new DegenerateTransformException("Matrix is NaN. Check input values.");
+            }
+
             return matrix;
         }
 
@@ -315,4 +320,4 @@ namespace SixLabors.ImageSharp.Processing
             return this;
         }
     }
-}
+}

tests/ImageSharp.Tests/Processing/Transforms/AffineTransformBuilderTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System.Numerics;
@@ -8,7 +8,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
 {
     public class AffineTransformBuilderTests : TransformBuilderTestBase<AffineTransformBuilder>
     {
-        protected override AffineTransformBuilder CreateBuilder(Rectangle rectangle) => new AffineTransformBuilder();
+        protected override AffineTransformBuilder CreateBuilder()
+            => new AffineTransformBuilder();
 
         protected override void AppendRotationDegrees(AffineTransformBuilder builder, float degrees)
             => builder.AppendRotationDegrees(degrees);
@@ -67,4 +68,4 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             return Vector2.Transform(sourcePoint, matrix);
         }
     }
-}
+}

tests/ImageSharp.Tests/Processing/Transforms/ProjectiveTransformBuilderTests.cs

@@ -1,6 +1,7 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
+using System;
 using System.Numerics;
 using SixLabors.ImageSharp.Processing;
 
@@ -8,20 +9,25 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
 {
     public class ProjectiveTransformBuilderTests : TransformBuilderTestBase<ProjectiveTransformBuilder>
     {
-        protected override ProjectiveTransformBuilder CreateBuilder(Rectangle rectangle) => new ProjectiveTransformBuilder();
+        protected override ProjectiveTransformBuilder CreateBuilder()
+            => new ProjectiveTransformBuilder();
 
-        protected override void AppendRotationDegrees(ProjectiveTransformBuilder builder, float degrees) => builder.AppendRotationDegrees(degrees);
+        protected override void AppendRotationDegrees(ProjectiveTransformBuilder builder, float degrees)
+            => builder.AppendRotationDegrees(degrees);
 
-        protected override void AppendRotationDegrees(ProjectiveTransformBuilder builder, float degrees, Vector2 origin) => builder.AppendRotationDegrees(degrees, origin);
+        protected override void AppendRotationDegrees(ProjectiveTransformBuilder builder, float degrees, Vector2 origin)
+            => builder.AppendRotationDegrees(degrees, origin);
 
-        protected override void AppendRotationRadians(ProjectiveTransformBuilder builder, float radians) => builder.AppendRotationRadians(radians);
+        protected override void AppendRotationRadians(ProjectiveTransformBuilder builder, float radians)
+            => builder.AppendRotationRadians(radians);
 
-        protected override void AppendRotationRadians(ProjectiveTransformBuilder builder, float radians, Vector2 origin) => builder.AppendRotationRadians(radians, origin);
+        protected override void AppendRotationRadians(ProjectiveTransformBuilder builder, float radians, Vector2 origin)
+            => builder.AppendRotationRadians(radians, origin);
 
         protected override void AppendScale(ProjectiveTransformBuilder builder, SizeF scale) => builder.AppendScale(scale);
 
         protected override void AppendSkewDegrees(ProjectiveTransformBuilder builder, float degreesX, float degreesY)
-    => builder.AppendSkewDegrees(degreesX, degreesY);
+            => builder.AppendSkewDegrees(degreesX, degreesY);
 
         protected override void AppendSkewDegrees(ProjectiveTransformBuilder builder, float degreesX, float degreesY, Vector2 origin)
             => builder.AppendSkewDegrees(degreesX, degreesY, origin);
@@ -44,7 +50,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         protected override void PrependSkewRadians(ProjectiveTransformBuilder builder, float radiansX, float radiansY, Vector2 origin)
             => builder.PrependSkewRadians(radiansX, radiansY, origin);
 
-        protected override void PrependTranslation(ProjectiveTransformBuilder builder, PointF translate) => builder.PrependTranslation(translate);
+        protected override void PrependTranslation(ProjectiveTransformBuilder builder, PointF translate)
+            => builder.PrependTranslation(translate);
 
         protected override void PrependRotationRadians(ProjectiveTransformBuilder builder, float radians, Vector2 origin) =>
             builder.PrependRotationRadians(radians, origin);

tests/ImageSharp.Tests/Processing/Transforms/TransformBuilderTestBase.cs

@@ -31,7 +31,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         {
             // These operations should be size-agnostic:
             var size = new Size(123, 321);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             this.AppendScale(builder, new SizeF(scale));
             this.AppendTranslation(builder, translate);
@@ -57,7 +57,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         {
             // Translate ans scale are size-agnostic:
             var size = new Size(456, 432);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             this.AppendTranslation(builder, translate);
             this.AppendScale(builder, new SizeF(scale));
@@ -72,7 +72,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         public void LocationOffsetIsPrepended(int locationX, int locationY)
         {
             var rectangle = new Rectangle(locationX, locationY, 10, 10);
-            TBuilder builder = this.CreateBuilder(rectangle);
+            TBuilder builder = this.CreateBuilder();
 
             this.AppendScale(builder, new SizeF(2, 2));
 
@@ -94,7 +94,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             float y)
         {
             var size = new Size(width, height);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             this.AppendRotationDegrees(builder, degrees);
 
@@ -122,7 +122,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             float y)
         {
             var size = new Size(width, height);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             var centerPoint = new Vector2(cx, cy);
             this.AppendRotationDegrees(builder, degrees, centerPoint);
@@ -149,7 +149,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             float y)
         {
             var size = new Size(width, height);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             this.AppendSkewDegrees(builder, degreesX, degreesY);
 
@@ -176,7 +176,7 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             float y)
         {
             var size = new Size(width, height);
-            TBuilder builder = this.CreateBuilder(size);
+            TBuilder builder = this.CreateBuilder();
 
             var centerPoint = new Vector2(cx, cy);
             this.AppendSkewDegrees(builder, degreesX, degreesY, centerPoint);
@@ -194,8 +194,8 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
         public void AppendPrependOpposite()
         {
             var rectangle = new Rectangle(-1, -1, 3, 3);
-            TBuilder b1 = this.CreateBuilder(rectangle);
-            TBuilder b2 = this.CreateBuilder(rectangle);
+            TBuilder b1 = this.CreateBuilder();
+            TBuilder b2 = this.CreateBuilder();
 
             const float pi = (float)Math.PI;
 
@@ -232,14 +232,24 @@ namespace SixLabors.ImageSharp.Tests.Processing.Transforms
             Assert.ThrowsAny<ArgumentOutOfRangeException>(
                 () =>
                     {
-                        TBuilder builder = this.CreateBuilder(size);
+                        TBuilder builder = this.CreateBuilder();
                         this.Execute(builder, new Rectangle(Point.Empty, size), Vector2.Zero);
                     });
         }
 
-        protected TBuilder CreateBuilder(Size size) => this.CreateBuilder(new Rectangle(Point.Empty, size));
+        [Fact]
+        public void ThrowsForInvalidMatrix()
+        {
+            Assert.ThrowsAny<DegenerateTransformException>(
+                () =>
+                {
+                    TBuilder builder = this.CreateBuilder();
+                    this.AppendSkewDegrees(builder, 45, 45);
+                    this.Execute(builder, new Rectangle(0, 0, 150, 150), Vector2.Zero);
+                });
+        }
 
-        protected abstract TBuilder CreateBuilder(Rectangle rectangle);
+        protected abstract TBuilder CreateBuilder();
 
         protected abstract void AppendRotationDegrees(TBuilder builder, float degrees);