Fix transform bounds calculations

Author: JimBobSquarePants

src/ImageSharp/Processing/AffineTransformBuilder.cs

@@ -12,7 +12,6 @@ namespace SixLabors.ImageSharp.Processing;
 public class AffineTransformBuilder
 {
     private readonly List<Func<Size, Matrix3x2>> transformMatrixFactories = new();
-    private readonly List<Func<Size, Matrix3x2>> boundsMatrixFactories = new();
 
     /// <summary>
     /// Prepends a rotation matrix using the given rotation angle in degrees
@@ -31,8 +30,7 @@ public AffineTransformBuilder PrependRotationDegrees(float degrees)
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder PrependRotationRadians(float radians)
         => this.Prepend(
-            size => TransformUtils.CreateRotationTransformMatrixRadians(radians, size),
-            size => TransformUtils.CreateRotationBoundsMatrixRadians(radians, size));
+            size => TransformUtils.CreateRotationTransformMatrixRadians(radians, size));
 
     /// <summary>
     /// Prepends a rotation matrix using the given rotation in degrees at the given origin.
@@ -68,9 +66,7 @@ public AffineTransformBuilder AppendRotationDegrees(float degrees)
     /// <param name="radians">The amount of rotation, in radians.</param>
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder AppendRotationRadians(float radians)
-        => this.Append(
-            size => TransformUtils.CreateRotationTransformMatrixRadians(radians, size),
-            size => TransformUtils.CreateRotationBoundsMatrixRadians(radians, size));
+        => this.Append(size => TransformUtils.CreateRotationTransformMatrixRadians(radians, size));
 
     /// <summary>
     /// Appends a rotation matrix using the given rotation in degrees at the given origin.
@@ -145,9 +141,7 @@ public AffineTransformBuilder AppendScale(Vector2 scales)
     /// <param name="degreesY">The Y angle, in degrees.</param>
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder PrependSkewDegrees(float degreesX, float degreesY)
-        => this.Prepend(
-            size => TransformUtils.CreateSkewTransformMatrixDegrees(degreesX, degreesY, size),
-            size => TransformUtils.CreateSkewBoundsMatrixDegrees(degreesX, degreesY, size));
+        => this.Prepend(size => TransformUtils.CreateSkewTransformMatrixDegrees(degreesX, degreesY, size));
 
     /// <summary>
     /// Prepends a centered skew matrix from the give angles in radians.
@@ -156,9 +150,7 @@ public AffineTransformBuilder PrependSkewDegrees(float degreesX, float degreesY)
     /// <param name="radiansY">The Y angle, in radians.</param>
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder PrependSkewRadians(float radiansX, float radiansY)
-        => this.Prepend(
-            size => TransformUtils.CreateSkewTransformMatrixRadians(radiansX, radiansY, size),
-            size => TransformUtils.CreateSkewBoundsMatrixRadians(radiansX, radiansY, size));
+        => this.Prepend(size => TransformUtils.CreateSkewTransformMatrixRadians(radiansX, radiansY, size));
 
     /// <summary>
     /// Prepends a skew matrix using the given angles in degrees at the given origin.
@@ -187,9 +179,7 @@ public AffineTransformBuilder PrependSkewRadians(float radiansX, float radiansY,
     /// <param name="degreesY">The Y angle, in degrees.</param>
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder AppendSkewDegrees(float degreesX, float degreesY)
-        => this.Append(
-            size => TransformUtils.CreateSkewTransformMatrixDegrees(degreesX, degreesY, size),
-            size => TransformUtils.CreateSkewBoundsMatrixDegrees(degreesX, degreesY, size));
+        => this.Append(size => TransformUtils.CreateSkewTransformMatrixDegrees(degreesX, degreesY, size));
 
     /// <summary>
     /// Appends a centered skew matrix from the give angles in radians.
@@ -198,9 +188,7 @@ public AffineTransformBuilder AppendSkewDegrees(float degreesX, float degreesY)
     /// <param name="radiansY">The Y angle, in radians.</param>
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder AppendSkewRadians(float radiansX, float radiansY)
-        => this.Append(
-            size => TransformUtils.CreateSkewTransformMatrixRadians(radiansX, radiansY, size),
-            size => TransformUtils.CreateSkewBoundsMatrixRadians(radiansX, radiansY, size));
+        => this.Append(size => TransformUtils.CreateSkewTransformMatrixRadians(radiansX, radiansY, size));
 
     /// <summary>
     /// Appends a skew matrix using the given angles in degrees at the given origin.
@@ -267,7 +255,7 @@ public AffineTransformBuilder AppendTranslation(Vector2 position)
     public AffineTransformBuilder PrependMatrix(Matrix3x2 matrix)
     {
         CheckDegenerate(matrix);
-        return this.Prepend(_ => matrix, _ => matrix);
+        return this.Prepend(_ => matrix);
     }
 
     /// <summary>
@@ -283,7 +271,7 @@ public AffineTransformBuilder PrependMatrix(Matrix3x2 matrix)
     public AffineTransformBuilder AppendMatrix(Matrix3x2 matrix)
     {
         CheckDegenerate(matrix);
-        return this.Append(_ => matrix, _ => matrix);
+        return this.Append(_ => matrix);
     }
 
     /// <summary>
@@ -340,13 +328,13 @@ public Size GetTransformedSize(Rectangle sourceRectangle)
         // Translate the origin matrix to cater for source rectangle offsets.
         Matrix3x2 matrix = Matrix3x2.CreateTranslation(-sourceRectangle.Location);
 
-        foreach (Func<Size, Matrix3x2> factory in this.boundsMatrixFactories)
+        foreach (Func<Size, Matrix3x2> factory in this.transformMatrixFactories)
         {
             matrix *= factory(size);
             CheckDegenerate(matrix);
         }
 
-        return TransformUtils.GetTransformedSize(size, matrix);
+        return TransformUtils.GetTransformedSize(matrix, size);
     }
 
     private static void CheckDegenerate(Matrix3x2 matrix)
@@ -357,17 +345,15 @@ private static void CheckDegenerate(Matrix3x2 matrix)
         }
     }
 
-    private AffineTransformBuilder Prepend(Func<Size, Matrix3x2> transformFactory, Func<Size, Matrix3x2> boundsFactory)
+    private AffineTransformBuilder Prepend(Func<Size, Matrix3x2> transformFactory)
     {
         this.transformMatrixFactories.Insert(0, transformFactory);
-        this.boundsMatrixFactories.Insert(0, boundsFactory);
         return this;
     }
 
-    private AffineTransformBuilder Append(Func<Size, Matrix3x2> transformFactory, Func<Size, Matrix3x2> boundsFactory)
+    private AffineTransformBuilder Append(Func<Size, Matrix3x2> transformFactory)
     {
         this.transformMatrixFactories.Add(transformFactory);
-        this.boundsMatrixFactories.Add(boundsFactory);
         return this;
     }
 }

src/ImageSharp/Processing/Processors/Transforms/Linear/LinearTransformUtility.cs

@@ -43,7 +43,7 @@ public static float GetSamplingRadius<TResampler>(in TResampler sampler, int sou
     /// <returns>The <see cref="int"/>.</returns>
     [MethodImpl(InliningOptions.ShortMethod)]
     public static int GetRangeStart(float radius, float center, int min, int max)
-        => Numerics.Clamp((int)MathF.Ceiling(center - radius), min, max);
+        => Numerics.Clamp((int)MathF.Floor(center - radius), min, max);
 
     /// <summary>
     /// Gets the end position (inclusive) for a sampling range given
@@ -56,5 +56,5 @@ public static int GetRangeStart(float radius, float center, int min, int max)
     /// <returns>The <see cref="int"/>.</returns>
     [MethodImpl(InliningOptions.ShortMethod)]
     public static int GetRangeEnd(float radius, float center, int min, int max)
-        => Numerics.Clamp((int)MathF.Floor(center + radius), min, max);
+        => Numerics.Clamp((int)MathF.Ceiling(center + radius), min, max);
 }

src/ImageSharp/Processing/Processors/Transforms/Linear/RotateProcessor.cs

@@ -29,14 +29,13 @@ public RotateProcessor(float degrees, Size sourceSize)
     public RotateProcessor(float degrees, IResampler sampler, Size sourceSize)
         : this(
             TransformUtils.CreateRotationTransformMatrixDegrees(degrees, sourceSize),
-            TransformUtils.CreateRotationBoundsMatrixDegrees(degrees, sourceSize),
             sampler,
             sourceSize)
         => this.Degrees = degrees;
 
     // Helper constructor
-    private RotateProcessor(Matrix3x2 rotationMatrix, Matrix3x2 boundsMatrix, IResampler sampler, Size sourceSize)
-        : base(rotationMatrix, sampler, TransformUtils.GetTransformedSize(sourceSize, boundsMatrix))
+    private RotateProcessor(Matrix3x2 rotationMatrix, IResampler sampler, Size sourceSize)
+        : base(rotationMatrix, sampler, TransformUtils.GetTransformedSize(rotationMatrix, sourceSize))
     {
     }
 

src/ImageSharp/Processing/Processors/Transforms/Linear/SkewProcessor.cs

@@ -31,7 +31,6 @@ public SkewProcessor(float degreesX, float degreesY, Size sourceSize)
     public SkewProcessor(float degreesX, float degreesY, IResampler sampler, Size sourceSize)
         : this(
              TransformUtils.CreateSkewTransformMatrixDegrees(degreesX, degreesY, sourceSize),
-             TransformUtils.CreateSkewBoundsMatrixDegrees(degreesX, degreesY, sourceSize),
              sampler,
              sourceSize)
     {
@@ -40,8 +39,8 @@ public SkewProcessor(float degreesX, float degreesY, IResampler sampler, Size so
     }
 
     // Helper constructor:
-    private SkewProcessor(Matrix3x2 skewMatrix, Matrix3x2 boundsMatrix, IResampler sampler, Size sourceSize)
-        : base(skewMatrix, sampler, TransformUtils.GetTransformedSize(sourceSize, boundsMatrix))
+    private SkewProcessor(Matrix3x2 skewMatrix, IResampler sampler, Size sourceSize)
+        : base(skewMatrix, sampler, TransformUtils.GetTransformedSize(skewMatrix, sourceSize))
     {
     }