Merge pull request #3011 from SixLabors/js/fix-3000

Fix off-by-one errors when transforming images.

Author: JimBobSquarePants

src/ImageSharp/Metadata/Profiles/Exif/ExifProfile.cs

@@ -318,7 +318,7 @@ internal void SyncSubject(int width, int height, Matrix4x4 matrix)
         {
             if (location.Value?.Length == 2)
             {
-                Vector2 point = TransformUtils.ProjectiveTransform2D(location.Value[0], location.Value[1], matrix);
+                Vector2 point = TransformUtilities.ProjectiveTransform2D(location.Value[0], location.Value[1], matrix);
 
                 // Ensure the point is within the image dimensions.
                 point = Vector2.Clamp(point, Vector2.Zero, new Vector2(width - 1, height - 1));
@@ -340,18 +340,18 @@ internal void SyncSubject(int width, int height, Matrix4x4 matrix)
             if (area.Value?.Length == 4)
             {
                 RectangleF rectangle = new(area.Value[0], area.Value[1], area.Value[2], area.Value[3]);
-                if (!TransformUtils.TryGetTransformedRectangle(rectangle, matrix, out Rectangle bounds))
+                if (!TransformUtilities.TryGetTransformedRectangle(rectangle, matrix, out RectangleF bounds))
                 {
                     return;
                 }
 
                 // Ensure the bounds are within the image dimensions.
-                bounds = Rectangle.Intersect(bounds, new Rectangle(0, 0, width, height));
+                bounds = RectangleF.Intersect(bounds, new Rectangle(0, 0, width, height));
 
-                area.Value[0] = (ushort)bounds.X;
-                area.Value[1] = (ushort)bounds.Y;
-                area.Value[2] = (ushort)bounds.Width;
-                area.Value[3] = (ushort)bounds.Height;
+                area.Value[0] = (ushort)MathF.Floor(bounds.X);
+                area.Value[1] = (ushort)MathF.Floor(bounds.Y);
+                area.Value[2] = (ushort)MathF.Ceiling(bounds.Width);
+                area.Value[3] = (ushort)MathF.Ceiling(bounds.Height);
                 this.SetValue(ExifTag.SubjectArea, area.Value);
             }
             else

src/ImageSharp/Primitives/Point.cs

@@ -69,7 +69,7 @@ public Point(Size size)
     /// Gets a value indicating whether this <see cref="Point"/> is empty.
     /// </summary>
     [EditorBrowsable(EditorBrowsableState.Never)]
-    public bool IsEmpty => this.Equals(Empty);
+    public readonly bool IsEmpty => this.Equals(Empty);
 
     /// <summary>
     /// Creates a <see cref="PointF"/> with the coordinates of the specified <see cref="Point"/>.
@@ -239,7 +239,7 @@ public Point(Size size)
     /// </summary>
     /// <param name="x">The out value for X.</param>
     /// <param name="y">The out value for Y.</param>
-    public void Deconstruct(out int x, out int y)
+    public readonly void Deconstruct(out int x, out int y)
     {
         x = this.X;
         y = this.Y;
@@ -268,17 +268,17 @@ public void Offset(int dx, int dy)
     public void Offset(Point point) => this.Offset(point.X, point.Y);
 
     /// <inheritdoc/>
-    public override int GetHashCode() => HashCode.Combine(this.X, this.Y);
+    public override readonly int GetHashCode() => HashCode.Combine(this.X, this.Y);
 
     /// <inheritdoc/>
-    public override string ToString() => $"Point [ X={this.X}, Y={this.Y} ]";
+    public override readonly string ToString() => $"Point [ X={this.X}, Y={this.Y} ]";
 
     /// <inheritdoc/>
-    public override bool Equals(object? obj) => obj is Point other && this.Equals(other);
+    public override readonly bool Equals(object? obj) => obj is Point other && this.Equals(other);
 
     /// <inheritdoc/>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public bool Equals(Point other) => this.X.Equals(other.X) && this.Y.Equals(other.Y);
+    public readonly bool Equals(Point other) => this.X.Equals(other.X) && this.Y.Equals(other.Y);
 
     private static short HighInt16(int n) => unchecked((short)((n >> 16) & 0xffff));
 

src/ImageSharp/Primitives/PointF.cs

@@ -58,7 +58,7 @@ public PointF(SizeF size)
     /// Gets a value indicating whether this <see cref="PointF"/> is empty.
     /// </summary>
     [EditorBrowsable(EditorBrowsableState.Never)]
-    public bool IsEmpty => this.Equals(Empty);
+    public readonly bool IsEmpty => this.Equals(Empty);
 
     /// <summary>
     /// Creates a <see cref="Vector2"/> with the coordinates of the specified <see cref="PointF"/>.
@@ -251,7 +251,7 @@ public PointF(SizeF size)
     /// </summary>
     /// <param name="x">The out value for X.</param>
     /// <param name="y">The out value for Y.</param>
-    public void Deconstruct(out float x, out float y)
+    public readonly void Deconstruct(out float x, out float y)
     {
         x = this.X;
         y = this.Y;
@@ -277,15 +277,15 @@ public void Offset(float dx, float dy)
     public void Offset(PointF point) => this.Offset(point.X, point.Y);
 
     /// <inheritdoc/>
-    public override int GetHashCode() => HashCode.Combine(this.X, this.Y);
+    public override readonly int GetHashCode() => HashCode.Combine(this.X, this.Y);
 
     /// <inheritdoc/>
-    public override string ToString() => $"PointF [ X={this.X}, Y={this.Y} ]";
+    public override readonly string ToString() => $"PointF [ X={this.X}, Y={this.Y} ]";
 
     /// <inheritdoc/>
-    public override bool Equals(object? obj) => obj is PointF pointF && this.Equals(pointF);
+    public override readonly bool Equals(object? obj) => obj is PointF pointF && this.Equals(pointF);
 
     /// <inheritdoc/>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public bool Equals(PointF other) => this.X.Equals(other.X) && this.Y.Equals(other.Y);
+    public readonly bool Equals(PointF other) => this.X.Equals(other.X) && this.Y.Equals(other.Y);
 }

src/ImageSharp/Primitives/SizeF.cs

@@ -67,7 +67,7 @@ public SizeF(PointF point)
     /// Gets a value indicating whether this <see cref="SizeF"/> is empty.
     /// </summary>
     [EditorBrowsable(EditorBrowsableState.Never)]
-    public bool IsEmpty => this.Equals(Empty);
+    public readonly bool IsEmpty => this.Equals(Empty);
 
     /// <summary>
     /// Creates a <see cref="Vector2"/> with the coordinates of the specified <see cref="PointF"/>.
@@ -201,24 +201,24 @@ public static SizeF Transform(SizeF size, Matrix3x2 matrix)
     /// </summary>
     /// <param name="width">The out value for the width.</param>
     /// <param name="height">The out value for the height.</param>
-    public void Deconstruct(out float width, out float height)
+    public readonly void Deconstruct(out float width, out float height)
     {
         width = this.Width;
         height = this.Height;
     }
 
     /// <inheritdoc/>
-    public override int GetHashCode() => HashCode.Combine(this.Width, this.Height);
+    public override readonly int GetHashCode() => HashCode.Combine(this.Width, this.Height);
 
     /// <inheritdoc/>
-    public override string ToString() => $"SizeF [ Width={this.Width}, Height={this.Height} ]";
+    public override readonly string ToString() => $"SizeF [ Width={this.Width}, Height={this.Height} ]";
 
     /// <inheritdoc/>
-    public override bool Equals(object? obj) => obj is SizeF && this.Equals((SizeF)obj);
+    public override readonly bool Equals(object? obj) => obj is SizeF sizeF && this.Equals(sizeF);
 
     /// <inheritdoc/>
     [MethodImpl(MethodImplOptions.AggressiveInlining)]
-    public bool Equals(SizeF other) => this.Width.Equals(other.Width) && this.Height.Equals(other.Height);
+    public readonly bool Equals(SizeF other) => this.Width.Equals(other.Width) && this.Height.Equals(other.Height);
 
     /// <summary>
     /// Multiplies <see cref="SizeF"/> by a <see cref="float"/> producing <see cref="SizeF"/>.

src/ImageSharp/Processing/AffineTransformBuilder.cs

@@ -17,24 +17,9 @@ public class AffineTransformBuilder
     /// Initializes a new instance of the <see cref="AffineTransformBuilder"/> class.
     /// </summary>
     public AffineTransformBuilder()
-        : this(TransformSpace.Pixel)
     {
     }
 
-    /// <summary>
-    /// Initializes a new instance of the <see cref="AffineTransformBuilder"/> class.
-    /// </summary>
-    /// <param name="transformSpace">
-    /// The <see cref="TransformSpace"/> to use when applying the affine transform.
-    /// </param>
-    public AffineTransformBuilder(TransformSpace transformSpace)
-        => this.TransformSpace = transformSpace;
-
-    /// <summary>
-    /// Gets the <see cref="TransformSpace"/> to use when applying the affine transform.
-    /// </summary>
-    public TransformSpace TransformSpace { get; }
-
     /// <summary>
     /// Prepends a rotation matrix using the given rotation angle in degrees
     /// and the image center point as rotation center.
@@ -52,7 +37,7 @@ public AffineTransformBuilder PrependRotationDegrees(float degrees)
     /// <returns>The <see cref="AffineTransformBuilder"/>.</returns>
     public AffineTransformBuilder PrependRotationRadians(float radians)
         => this.Prepend(
-            size => TransformUtils.CreateRotationTransformMatrixRadians(radians, size, this.TransformSpace));
+            size => TransformUtilities.CreateRotationTransformMatrixRadians(radians, size));
 
     /// <summary>
     /// Prepends a rotation matrix using the given rotation in degrees at the given origin.
@@ -88,7 +73,7 @@ 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, this.TransformSpace));
+        => this.Append(size => TransformUtilities.CreateRotationTransformMatrixRadians(radians, size));
 
     /// <summary>
     /// Appends a rotation matrix using the given rotation in degrees at the given origin.
@@ -172,7 +157,7 @@ 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, this.TransformSpace));
+        => this.Prepend(size => TransformUtilities.CreateSkewTransformMatrixRadians(radiansX, radiansY, size));
 
     /// <summary>
     /// Prepends a skew matrix using the given angles in degrees at the given origin.
@@ -210,7 +195,7 @@ 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, this.TransformSpace));
+        => this.Append(size => TransformUtilities.CreateSkewTransformMatrixRadians(radiansX, radiansY, size));
 
     /// <summary>
     /// Appends a skew matrix using the given angles in degrees at the given origin.
@@ -344,15 +329,29 @@ public Matrix3x2 BuildMatrix(Rectangle sourceRectangle)
     /// for linear transforms.
     /// </exception>
     /// <returns>The <see cref="Size"/>.</returns>
-    public Size GetTransformedSize(Rectangle sourceRectangle)
+    public SizeF GetTransformedSize(Rectangle sourceRectangle)
     {
         Matrix3x2 matrix = this.BuildMatrix(sourceRectangle);
-        return TransformUtils.GetTransformedSize(matrix, sourceRectangle.Size, this.TransformSpace);
+        return GetTransformedSize(sourceRectangle, matrix);
     }
 
+    /// <summary>
+    /// Returns the size of a rectangle large enough to contain the transformed source rectangle.
+    /// </summary>
+    /// <param name="sourceRectangle">The rectangle in the source image.</param>
+    /// <param name="matrix">The transformation matrix.</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="Size"/>.</returns>
+    internal static SizeF GetTransformedSize(Rectangle sourceRectangle, Matrix3x2 matrix)
+        => TransformUtilities.GetRawTransformedSize(matrix, sourceRectangle.Size);
+
     private static void CheckDegenerate(Matrix3x2 matrix)
     {
-        if (TransformUtils.IsDegenerate(matrix))
+        if (TransformUtilities.IsDegenerate(matrix))
         {
             throw new DegenerateTransformException("Matrix is degenerate. Check input values.");
         }

src/ImageSharp/Processing/Extensions/Transforms/TransformExtensions.cs

@@ -7,8 +7,8 @@
 namespace SixLabors.ImageSharp.Processing;
 
 /// <summary>
-/// Defines extensions that allow the application of composable transform operations on an <see cref="Image"/>
-/// using Mutate/Clone.
+/// Defines extensions that allow the application of composable transform operations
+/// on an <see cref="IImageProcessingContext"/> using Mutate/Clone.
 /// </summary>
 public static class TransformExtensions
 {
@@ -51,7 +51,7 @@ public static IImageProcessingContext Transform(
         IResampler sampler)
     {
         Matrix3x2 transform = builder.BuildMatrix(sourceRectangle);
-        Size targetDimensions = builder.GetTransformedSize(sourceRectangle);
+        Size targetDimensions = TransformUtilities.GetTransformedCanvasSize(transform, sourceRectangle.Size);
         return source.Transform(sourceRectangle, transform, targetDimensions, sampler);
     }
 
@@ -113,7 +113,7 @@ public static IImageProcessingContext Transform(
         IResampler sampler)
     {
         Matrix4x4 transform = builder.BuildMatrix(sourceRectangle);
-        Size targetDimensions = builder.GetTransformedSize(sourceRectangle);
+        Size targetDimensions = TransformUtilities.GetTransformedCanvasSize(transform, sourceRectangle.Size);
         return source.Transform(sourceRectangle, transform, targetDimensions, sampler);
     }
 

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

@@ -21,7 +21,7 @@ public AffineTransformProcessor(Matrix3x2 matrix, IResampler sampler, Size targe
         Guard.NotNull(sampler, nameof(sampler));
         Guard.MustBeValueType(sampler);
 
-        if (TransformUtils.IsDegenerate(matrix))
+        if (TransformUtilities.IsDegenerate(matrix))
         {
             throw new DegenerateTransformException("Matrix is degenerate. Check input values.");
         }

src/ImageSharp/Processing/Processors/Transforms/Linear/AffineTransformProcessor{TPixel}.cs

@@ -77,7 +77,9 @@ public void ApplyTransform<TResampler>(in TResampler sampler)
             return;
         }
 
-        // Convert from screen to world space.
+        // All matrices are defined in normalized coordinate space so we need to convert to pixel space.
+        // After normalization we need to invert the matrix for correct sampling.
+        matrix = TransformUtilities.NormalizeToPixel(matrix);
         Matrix3x2.Invert(matrix, out matrix);
 
         if (sampler is NearestNeighborResampler)

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

@@ -21,7 +21,7 @@ public ProjectiveTransformProcessor(Matrix4x4 matrix, IResampler sampler, Size t
         Guard.NotNull(sampler, nameof(sampler));
         Guard.MustBeValueType(sampler);
 
-        if (TransformUtils.IsDegenerate(matrix))
+        if (TransformUtilities.IsDegenerate(matrix))
         {
             throw new DegenerateTransformException("Matrix is degenerate. Check input values.");
         }

src/ImageSharp/Processing/Processors/Transforms/Linear/ProjectiveTransformProcessor{TPixel}.cs

@@ -75,7 +75,9 @@ public void ApplyTransform<TResampler>(in TResampler sampler)
             return;
         }
 
-        // Convert from screen to world space.
+        // All matrices are defined in normalized coordinate space so we need to convert to pixel space.
+        // After normalization we need to invert the matrix for correct sampling.
+        matrix = TransformUtilities.NormalizeToPixel(matrix);
         Matrix4x4.Invert(matrix, out matrix);
 
         if (sampler is NearestNeighborResampler)
@@ -135,7 +137,7 @@ public void Invoke(int y)
 
             for (int x = 0; x < destinationRowSpan.Length; x++)
             {
-                Vector2 point = TransformUtils.ProjectiveTransform2D(x, y, this.matrix);
+                Vector2 point = TransformUtilities.ProjectiveTransform2D(x, y, this.matrix);
                 int px = (int)MathF.Round(point.X);
                 int py = (int)MathF.Round(point.Y);
 
@@ -207,7 +209,7 @@ public void Invoke(in RowInterval rows, Span<Vector4> span)
 
                 for (int x = 0; x < span.Length; x++)
                 {
-                    Vector2 point = TransformUtils.ProjectiveTransform2D(x, y, matrix);
+                    Vector2 point = TransformUtilities.ProjectiveTransform2D(x, y, matrix);
                     float pY = point.Y;
                     float pX = point.X;