Merge pull request #1181 from SixLabors/js/fix-966

Add DegenerateTransformException

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;
@@ -10,6 +10,13 @@ namespace SixLabors.ImageSharp
     /// </summary>
     public sealed 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 @@ public ImageProcessingException(string errorMessage, Exception innerException)
         {
         }
     }
-}
+}

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;
@@ -247,15 +247,33 @@ public AffineTransformBuilder AppendTranslation(Vector2 position)
         /// Prepends a raw matrix.
         /// </summary>
         /// <param name="matrix">The matrix to prepend.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
-        public AffineTransformBuilder PrependMatrix(Matrix3x2 matrix) => this.Prepend(_ => matrix);
+        public AffineTransformBuilder PrependMatrix(Matrix3x2 matrix)
+        {
+            CheckDegenerate(matrix);
+            return this.Prepend(_ => matrix);
+        }
 
         /// <summary>
         /// Appends a raw matrix.
         /// </summary>
         /// <param name="matrix">The matrix to append.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
-        public AffineTransformBuilder AppendMatrix(Matrix3x2 matrix) => this.Append(_ => matrix);
+        public AffineTransformBuilder AppendMatrix(Matrix3x2 matrix)
+        {
+            CheckDegenerate(matrix);
+            return this.Append(_ => matrix);
+        }
 
         /// <summary>
         /// Returns the combined matrix for a given source size.
@@ -268,6 +286,11 @@ public AffineTransformBuilder AppendTranslation(Vector2 position)
         /// Returns the combined matrix for a given source rectangle.
         /// </summary>
         /// <param name="sourceRectangle">The rectangle in the source image.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="Matrix3x2"/>.</returns>
         public Matrix3x2 BuildMatrix(Rectangle sourceRectangle)
         {
@@ -284,9 +307,19 @@ public Matrix3x2 BuildMatrix(Rectangle sourceRectangle)
                 matrix *= factory(size);
             }
 
+            CheckDegenerate(matrix);
+
             return matrix;
         }
 
+        private static void CheckDegenerate(Matrix3x2 matrix)
+        {
+            if (TransformUtilities.IsDegenerate(matrix))
+            {
+                throw new DegenerateTransformException("Matrix is degenerate. Check input values.");
+            }
+        }
+
         private AffineTransformBuilder Prepend(Func<Size, Matrix3x2> factory)
         {
             this.matrixFactories.Insert(0, factory);
@@ -299,4 +332,4 @@ private AffineTransformBuilder Append(Func<Size, Matrix3x2> factory)
             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 : Exception
+    {
+        /// <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 +12,57 @@ namespace SixLabors.ImageSharp.Processing.Processors.Transforms
     /// </summary>
     internal static class TransformUtilities
     {
+        /// <summary>
+        /// Returns a value that indicates whether the specified matrix is degenerate
+        /// containing one or more values equivalent to <see cref="float.NaN"/> or a
+        /// zero determinant and therefore cannot be used for linear transforms.
+        /// </summary>
+        /// <param name="matrix">The transform matrix.</param>
+        public static bool IsDegenerate(Matrix3x2 matrix)
+            => IsNaN(matrix) || IsZero(matrix.GetDeterminant());
+
+        /// <summary>
+        /// Returns a value that indicates whether the specified matrix is degenerate
+        /// containing one or more values equivalent to <see cref="float.NaN"/> or a
+        /// zero determinant and therefore cannot be used for linear transforms.
+        /// </summary>
+        /// <param name="matrix">The transform matrix.</param>
+        public static bool IsDegenerate(Matrix4x4 matrix)
+            => IsNaN(matrix) || IsZero(matrix.GetDeterminant());
+
+        [MethodImpl(InliningOptions.ShortMethod)]
+        private static bool IsZero(float a)
+            => a > -Constants.EpsilonSquared && a < Constants.EpsilonSquared;
+
+        /// <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

@@ -1,9 +1,10 @@
-// Copyright (c) Six Labors and contributors.
+// Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
 using System.Collections.Generic;
 using System.Numerics;
+using System.Runtime.CompilerServices;
 using SixLabors.ImageSharp.Processing.Processors.Transforms;
 
 namespace SixLabors.ImageSharp.Processing
@@ -263,27 +264,51 @@ public ProjectiveTransformBuilder AppendTranslation(Vector2 position)
         /// Prepends a raw matrix.
         /// </summary>
         /// <param name="matrix">The matrix to prepend.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="ProjectiveTransformBuilder"/>.</returns>
-        public ProjectiveTransformBuilder PrependMatrix(Matrix4x4 matrix) => this.Prepend(_ => matrix);
+        public ProjectiveTransformBuilder PrependMatrix(Matrix4x4 matrix)
+        {
+            CheckDegenerate(matrix);
+            return this.Prepend(_ => matrix);
+        }
 
         /// <summary>
         /// Appends a raw matrix.
         /// </summary>
         /// <param name="matrix">The matrix to append.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="ProjectiveTransformBuilder"/>.</returns>
-        public ProjectiveTransformBuilder AppendMatrix(Matrix4x4 matrix) => this.Append(_ => matrix);
+        public ProjectiveTransformBuilder AppendMatrix(Matrix4x4 matrix)
+        {
+            CheckDegenerate(matrix);
+            return this.Append(_ => matrix);
+        }
 
         /// <summary>
         /// Returns the combined matrix for a given source size.
         /// </summary>
         /// <param name="sourceSize">The source image size.</param>
         /// <returns>The <see cref="Matrix4x4"/>.</returns>
-        public Matrix4x4 BuildMatrix(Size sourceSize) => this.BuildMatrix(new Rectangle(Point.Empty, sourceSize));
+        public Matrix4x4 BuildMatrix(Size sourceSize)
+            => this.BuildMatrix(new Rectangle(Point.Empty, sourceSize));
 
         /// <summary>
         /// Returns the combined matrix for a given source rectangle.
         /// </summary>
         /// <param name="sourceRectangle">The rectangle in the source image.</param>
+        /// <exception cref="DegenerateTransformException">
+        /// The resultant matrix is degenerate containing one or more values equivalent
+        /// to <see cref="float.NaN"/> or a zero determinant and therefore cannot be used
+        /// for linear transforms.
+        /// </exception>
         /// <returns>The <see cref="Matrix4x4"/>.</returns>
         public Matrix4x4 BuildMatrix(Rectangle sourceRectangle)
         {
@@ -300,9 +325,19 @@ public Matrix4x4 BuildMatrix(Rectangle sourceRectangle)
                 matrix *= factory(size);
             }
 
+            CheckDegenerate(matrix);
+
             return matrix;
         }
 
+        private static void CheckDegenerate(Matrix4x4 matrix)
+        {
+            if (TransformUtilities.IsDegenerate(matrix))
+            {
+                throw new DegenerateTransformException("Matrix is degenerate. Check input values.");
+            }
+        }
+
         private ProjectiveTransformBuilder Prepend(Func<Size, Matrix4x4> factory)
         {
             this.matrixFactories.Insert(0, factory);
@@ -315,4 +350,4 @@ private ProjectiveTransformBuilder Append(Func<Size, Matrix4x4> factory)
             return this;
         }
     }
-}
+}

tests/ImageSharp.Tests/Drawing/DrawImageExtensionsTests.cs

@@ -1,25 +1,17 @@
 // Copyright (c) Six Labors and contributors.
 // Licensed under the Apache License, Version 2.0.
 
-using System;
-using System.Linq;
-using Moq;
-using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.Advanced;
-using SixLabors.ImageSharp.Formats.Png;
 using SixLabors.ImageSharp.PixelFormats;
 using SixLabors.ImageSharp.Processing;
 using SixLabors.ImageSharp.Processing.Processors.Drawing;
 using SixLabors.ImageSharp.Tests.Processing;
-using SixLabors.ImageSharp.Tests.TestUtilities.ImageComparison;
 
 using Xunit;
 
 namespace SixLabors.ImageSharp.Tests.Drawing
 {
     public class DrawImageExtensionsTests : BaseImageOperationsExtensionTest
     {
-
         [Fact]
         public void DrawImage_OpacityOnly_VerifyGraphicOptionsTakenFromContext()
         {
@@ -28,7 +20,7 @@ public void DrawImage_OpacityOnly_VerifyGraphicOptionsTakenFromContext()
             this.options.ColorBlendingMode = PixelColorBlendingMode.Screen;
 
             this.operations.DrawImage(null, 0.5f);
-            var dip = this.Verify<DrawImageProcessor>();
+            DrawImageProcessor dip = this.Verify<DrawImageProcessor>();
 
             Assert.Equal(0.5, dip.Opacity);
             Assert.Equal(this.options.AlphaCompositionMode, dip.AlphaCompositionMode);
@@ -43,7 +35,7 @@ public void DrawImage_OpacityAndBlending_VerifyGraphicOptionsTakenFromContext()
             this.options.ColorBlendingMode = PixelColorBlendingMode.Screen;
 
             this.operations.DrawImage(null, PixelColorBlendingMode.Multiply, 0.5f);
-            var dip = this.Verify<DrawImageProcessor>();
+            DrawImageProcessor dip = this.Verify<DrawImageProcessor>();
 
             Assert.Equal(0.5, dip.Opacity);
             Assert.Equal(this.options.AlphaCompositionMode, dip.AlphaCompositionMode);
@@ -58,7 +50,7 @@ public void DrawImage_LocationAndOpacity_VerifyGraphicOptionsTakenFromContext()
             this.options.ColorBlendingMode = PixelColorBlendingMode.Screen;
 
             this.operations.DrawImage(null, Point.Empty, 0.5f);
-            var dip = this.Verify<DrawImageProcessor>();
+            DrawImageProcessor dip = this.Verify<DrawImageProcessor>();
 
             Assert.Equal(0.5, dip.Opacity);
             Assert.Equal(this.options.AlphaCompositionMode, dip.AlphaCompositionMode);
@@ -73,7 +65,7 @@ public void DrawImage_LocationAndOpacityAndBlending_VerifyGraphicOptionsTakenFro
             this.options.ColorBlendingMode = PixelColorBlendingMode.Screen;
 
             this.operations.DrawImage(null, Point.Empty, PixelColorBlendingMode.Multiply, 0.5f);
-            var dip = this.Verify<DrawImageProcessor>();
+            DrawImageProcessor dip = this.Verify<DrawImageProcessor>();
 
             Assert.Equal(0.5, dip.Opacity);
             Assert.Equal(this.options.AlphaCompositionMode, dip.AlphaCompositionMode);

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 @@ protected override void PrependTranslation(AffineTransformBuilder builder, Point
             return Vector2.Transform(sourcePoint, matrix);
         }
     }
-}
+}