Rotate and skew, shorter code fewer if, better math

Former-commit-id: 1c43328c71d549a566fe1c3a655f97c9ce9fad05
Former-commit-id: db8c7b880c3f17b85feb7277477eddc50f6dffb5
Former-commit-id: 405ff7e2dccdc33b5cbf53a07208a57528616c6b

src/ImageProcessorCore/Samplers/Processors/ProcessMatrixHelper.cs

@@ -0,0 +1,41 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Numerics;
+using System.Threading.Tasks;
+
+namespace ImageProcessorCore
+{
+
+    public static class ProcessMatrixHelper
+    {
+        public static void CreateNewTarget(ImageBase target, Rectangle sourceRectangle, Matrix3x2 processMatrix)
+        {
+            Matrix3x2 sizeMatrix;
+            if (Matrix3x2.Invert(processMatrix, out sizeMatrix))
+            {
+                Rectangle rectangle = ImageMaths.GetBoundingRectangle(sourceRectangle, sizeMatrix);
+                target.SetPixels(rectangle.Width, rectangle.Height, new float[rectangle.Width*rectangle.Height*4]);
+            }
+        }
+        public static Matrix3x2 Matrix3X2(ImageBase target, ImageBase source, Matrix3x2 processMatrix)
+        {
+            Matrix3x2 translationToTargetCenter = Matrix3x2.CreateTranslation(-target.Width / 2f, -target.Height / 2f);
+            Matrix3x2 translateToSourceCenter = Matrix3x2.CreateTranslation(source.Width / 2f, source.Height / 2f);
+            Matrix3x2 apply = (translationToTargetCenter * processMatrix) * translateToSourceCenter;
+            return apply;
+        }
+
+        public static void DrawHorizontalData(ImageBase target, ImageBase source, int y, Matrix3x2 apply)
+        {
+            for (int x = 0; x < target.Width; x++)
+            {
+                Point rotated = Point.Rotate(new Point(x, y), apply);
+                if (source.Bounds.Contains(rotated.X, rotated.Y))
+                {
+                    target[x, y] = source[rotated.X, rotated.Y];
+                }
+            }
+        }
+    }
+}

src/ImageProcessorCore/Samplers/Processors/RotateProcessor.cs

@@ -13,12 +13,10 @@ namespace ImageProcessorCore
     /// </summary>
     public class RotateProcessor : ImageSampler
     {
-        /// <summary>
-        /// The image used for storing the first pass pixels.
-        /// </summary>
+        private Matrix3x2 processMatrix;
 
         /// <summary>
-        /// The angle of rotation in degrees.
+        /// The angle of processMatrix in degrees.
         /// </summary>
         private float angle;
 
@@ -26,7 +24,7 @@ namespace ImageProcessorCore
         public override int Parallelism { get; set; } = 1;
 
         /// <summary>
-        /// Gets or sets the angle of rotation in degrees.
+        /// Gets or sets the angle of processMatrix in degrees.
         /// </summary>
         public float Angle
         {
@@ -40,8 +38,6 @@ namespace ImageProcessorCore
                 this.angle = value;
             }
         }
-
-
         /// <summary>
         /// Gets or sets a value indicating whether to expand the canvas to fit the rotated image.
         /// </summary>
@@ -50,50 +46,26 @@ namespace ImageProcessorCore
         /// <inheritdoc/>
         protected override void OnApply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
+            processMatrix = Point.CreateRotation(new Point(0, 0), -this.angle);
             if (this.Expand)
             {
-                // First find out how big the target rectangle should be.
-                Point centre = Rectangle.Center(sourceRectangle);
-                Matrix3x2 rotation = Point.CreateRotation(centre, -this.angle);
-                Rectangle rectangle = ImageMaths.GetBoundingRectangle(sourceRectangle, rotation);
-                target.SetPixels(rectangle.Width, rectangle.Height, new float[rectangle.Width * rectangle.Height * 4]);
+                processMatrix = Point.CreateRotation(new Point(0,0), -this.angle);
+                ProcessMatrixHelper.CreateNewTarget(target, sourceRectangle,processMatrix);
             }
         }
 
         /// <inheritdoc/>
         protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
         {
-
-            Matrix3x2 rotation = Point.CreateRotation(new Point(0, 0), -this.angle);
-            Matrix3x2 tran = Matrix3x2.CreateTranslation(-target.Width / 2f, -target.Height / 2f);
-            rotation = tran * rotation;
-            Matrix3x2 tran2 = Matrix3x2.CreateTranslation(source.Width / 2f, source.Height / 2f);
-            rotation = rotation * tran2;
-
-
+            var apply = ProcessMatrixHelper.Matrix3X2(target, source,processMatrix);
             Parallel.For(
                 0,
                 target.Height,
                 y =>
                 {
-                    for (int x = 0; x < target.Width; x++)
-                    {
-                        // Rotate at the centre point
-                        Point rotated = Point.Rotate(new Point(x, y), rotation);
-                        if (source.Bounds.Contains(rotated.X, rotated.Y))
-                        {
-                            target[x, y] = source[rotated.X, rotated.Y];
-                        }
-                    }
-
-                    this.OnRowProcessed();
+                    ProcessMatrixHelper.DrawHorizontalData(target, source, y, apply);
+                    OnRowProcessed();
                 });
         }
-
-        /// <inheritdoc/>
-        protected override void AfterApply(ImageBase source, ImageBase target, Rectangle targetRectangle, Rectangle sourceRectangle)
-        {
-
-        }
     }
 }

src/ImageProcessorCore/Samplers/Processors/SkewProcessor.cs

@@ -13,10 +13,7 @@ namespace ImageProcessorCore
     /// </summary>
     public class SkewProcessor : ImageSampler
     {
-        /// <summary>
-        /// The image used for storing the first pass pixels.
-        /// </summary>
-        private Image firstPass;
+        private Matrix3x2 processMatrix;
 
         /// <summary>
         /// The angle of rotation along the x-axis.
@@ -43,16 +40,6 @@ namespace ImageProcessorCore
 
             set
             {
-                if (value > 360)
-                {
-                    value -= 360;
-                }
-
-                if (value < 0)
-                {
-                    value += 360;
-                }
-
                 this.angleX = value;
             }
         }
@@ -69,16 +56,6 @@ namespace ImageProcessorCore
 
             set
             {
-                if (value > 360)
-                {
-                    value -= 360;
-                }
-
-                if (value < 0)
-                {
-                    value += 360;
-                }
-
                 this.angleY = value;
             }
         }
@@ -96,69 +73,26 @@ namespace ImageProcessorCore
         /// <inheritdoc/>
         protected override void OnApply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle)
         {
-            // If we are expanding we need to pad the bounds of the source rectangle.
-            // We can use the resizer in nearest neighbor mode to do this fairly quickly.
+            processMatrix = Point.CreateSkew(new Point(0, 0), -this.angleX, -this.angleY);
             if (this.Expand)
             {
-                // First find out how big the target rectangle should be.
-                Point centre = this.Center == Point.Empty ? Rectangle.Center(sourceRectangle) : this.Center;
-                Matrix3x2 skew = Point.CreateSkew(centre, -this.angleX, -this.angleY);
-                Rectangle rectangle = ImageMaths.GetBoundingRectangle(sourceRectangle, skew);
-                ResizeOptions options = new ResizeOptions
-                {
-                    Size = new Size(rectangle.Width, rectangle.Height),
-                    Mode = ResizeMode.BoxPad
-                };
-
-                // Get the padded bounds and resize the image.
-                Rectangle bounds = ResizeHelper.CalculateTargetLocationAndBounds(source, options);
-                this.firstPass = new Image(rectangle.Width, rectangle.Height);
-                target.SetPixels(rectangle.Width, rectangle.Height, new float[rectangle.Width * rectangle.Height * 4]);
-                new ResizeProcessor(new NearestNeighborResampler()).Apply(this.firstPass, source, rectangle.Width, rectangle.Height, bounds, sourceRectangle);
-            }
-            else
-            {
-                // Just clone the pixels across.
-                this.firstPass = new Image(source.Width, source.Height);
-                this.firstPass.ClonePixels(source.Width, source.Height, source.Pixels);
+                ProcessMatrixHelper.CreateNewTarget(target, sourceRectangle, processMatrix);
             }
         }
 
         /// <inheritdoc/>
         protected override void Apply(ImageBase target, ImageBase source, Rectangle targetRectangle, Rectangle sourceRectangle, int startY, int endY)
         {
-            int height = this.firstPass.Height;
-            int startX = 0;
-            int endX = this.firstPass.Width;
-            Point centre = this.Center == Point.Empty ? Rectangle.Center(this.firstPass.Bounds) : this.Center;
-            Matrix3x2 skew = Point.CreateSkew(centre, -this.angleX, -this.angleY);
-
-            // Since we are not working in parallel we use full height and width 
-            // of the first pass image.
+            var apply = ProcessMatrixHelper.Matrix3X2(target, source, processMatrix);
             Parallel.For(
                 0,
-                height,
+                target.Height,
                 y =>
                 {
-                    for (int x = startX; x < endX; x++)
-                    {
-                        // Skew at the centre point
-                        Point skewed = Point.Skew(new Point(x, y), skew);
-                        if (this.firstPass.Bounds.Contains(skewed.X, skewed.Y))
-                        {
-                            target[x, y] = this.firstPass[skewed.X, skewed.Y];
-                        }
-                    }
-
-                    this.OnRowProcessed();
+                    ProcessMatrixHelper.DrawHorizontalData(target, source, y, apply);
+                    OnRowProcessed();
                 });
-        }
 
-        /// <inheritdoc/>
-        protected override void AfterApply(ImageBase source, ImageBase target, Rectangle targetRectangle, Rectangle sourceRectangle)
-        {
-            // Cleanup.
-            this.firstPass.Dispose();
         }
     }
 }

tests/ImageProcessorCore.Tests/Processors/Samplers/SamplerTests.cs

@@ -471,7 +471,7 @@
                     using (Image image = new Image(stream))
                     using (FileStream output = File.OpenWrite($"TestOutput/Rotate/{filename}"))
                     {
-                        image.Rotate(20, this.ProgressUpdate)
+                        image.Rotate(-170, this.ProgressUpdate)
                              .Save(output);
                     }
 
@@ -500,7 +500,7 @@
                     using (Image image = new Image(stream))
                     using (FileStream output = File.OpenWrite($"TestOutput/Skew/{filename}"))
                     {
-                        image.Skew(20, 10, this.ProgressUpdate)
+                        image.Skew(-20, -10, this.ProgressUpdate)
                              .Save(output);
                     }