Fixing RotateBounds maths.

Former-commit-id: 8c5aff0a42bb1f05d3a092b638a71cd9c9cad55b
Former-commit-id: 29461154ae78d77b8884fc7ce621ce346079a4ba

src/ImageProcessor.Playground/Program.cs

@@ -52,7 +52,7 @@ namespace ImageProcessor.PlayGround
             // Image mask = Image.FromFile(Path.Combine(resolvedPath, "mask.png"));
             // Image overlay = Image.FromFile(Path.Combine(resolvedPath, "imageprocessor.128.png"));
             //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "2008.jpg"));
-            //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "new-york.jpg"));
+            //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "stretched.jpg"));
             //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "mountain.jpg"));
             //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "Arc-de-Triomphe-France.jpg"));
             //FileInfo fileInfo = new FileInfo(Path.Combine(resolvedPath, "Martin-Schoeller-Jack-Nicholson-Portrait.jpeg"));
@@ -110,19 +110,19 @@ namespace ImageProcessor.PlayGround
                             //.DetectEdges(new LaplacianOfGaussianEdgeFilter())
                             //.EntropyCrop()
                             //.Halftone(true)
-                            .RotateBounded(5, false)
+                            .RotateBounded(150, false)
+                            //.Rotate(140)
                             //.Filter(MatrixFilters.Invert)
                             //.Contrast(50)
                             //.Filter(MatrixFilters.Comic)
                             //.Flip()
                             //.Filter(MatrixFilters.HiSatch)
                             //.Pixelate(8)
-                            //.Rotate(45)
                             //.GaussianSharpen(10)
                             //.Format(new PngFormat() { IsIndexed = true })
-                            //.Format(new PngFormat() { IsIndexed = true })
+                            //.Format(new PngFormat() )
                             .Save(Path.GetFullPath(Path.Combine(Path.GetDirectoryName(path), @"..\..\images\output", fileInfo.Name)));
-                        //.Save(Path.GetFullPath(Path.Combine(Path.GetDirectoryName(path), @"..\..\images\output", Path.GetFileNameWithoutExtension(fileInfo.Name) + ".png")));
+                            //.Save(Path.GetFullPath(Path.Combine(Path.GetDirectoryName(path), @"..\..\images\output", Path.GetFileNameWithoutExtension(fileInfo.Name) + ".png")));
 
                         stopwatch.Stop();
                     }

src/ImageProcessor/Imaging/Helpers/ImageMaths.cs

@@ -113,6 +113,7 @@ namespace ImageProcessor.Imaging.Helpers
         /// <returns>The new size of the image</returns>
         public static Rectangle GetBoundingRotatedRectangle(int width, int height, float angleInDegrees)
         {
+            // Check first clockwise.
             double radians = DegreesToRadians(angleInDegrees);
             double radiansSin = Math.Sin(radians);
             double radiansCos = Math.Cos(radians);
@@ -316,14 +317,8 @@ namespace ImageProcessor.Imaging.Helpers
         /// <returns>The zoom needed</returns>
         public static float ZoomAfterRotation(int imageWidth, int imageHeight, float angleInDegrees)
         {
-            double radians = Math.Abs(DegreesToRadians(angleInDegrees));
+            Rectangle rectangle = GetBoundingRotatedRectangle(imageWidth, imageHeight, angleInDegrees);
-            double radiansSin = Math.Sin(radians);
+            return Math.Max((float)rectangle.Width / imageWidth, (float)rectangle.Height / imageHeight);
-            double radiansCos = Math.Cos(radians);
-
-            double widthRotated = (imageWidth * radiansCos) + (imageHeight * radiansSin);
-            double heightRotated = (imageWidth * radiansSin) + (imageHeight * radiansCos);
-
-            return (float)Math.Max(widthRotated / imageWidth, heightRotated / imageHeight);
         }
     }
 }

src/ImageProcessor/Processors/RotateBounded.cs

@@ -15,6 +15,7 @@ namespace ImageProcessor.Processors
     using System.Drawing;
     using System.Drawing.Drawing2D;
     using ImageProcessor.Common.Exceptions;
+    using ImageProcessor.Imaging.Helpers;
 
     /// <summary>
     /// Encapsulates the methods to rotate an image without expanding the canvas.
@@ -98,13 +99,13 @@ namespace ImageProcessor.Processors
         {
             Size newSize = new Size(image.Width, image.Height);
 
-            float zoom = Imaging.Helpers.ImageMaths.ZoomAfterRotation(image.Width, image.Height, angleInDegrees);
+            float zoom = ImageMaths.ZoomAfterRotation(image.Width, image.Height, angleInDegrees);
 
             // if we don't keep the image dimensions, calculate the new ones
             if (!keepSize)
             {
-                newSize.Width = (int)(newSize.Width / zoom);
+                newSize.Width = (int)Math.Floor(newSize.Width / zoom);
-                newSize.Height = (int)(newSize.Height / zoom);
+                newSize.Height = (int)Math.Floor(newSize.Height / zoom);
             }
 
             // Center of the image
@@ -143,22 +144,22 @@ namespace ImageProcessor.Processors
                 }
                 else
                 {
-                    // Calculate the difference between the center of the original image and the center 
+                    float previousX = rotateAtX;
-                    // of the new image.
+                    float previousY = rotateAtY;
-                    int x = (image.Width - newSize.Width) / 2;
-                    int y = (image.Height - newSize.Height) / 2;
 
-                    // Put the rotation point in the "center" of the old image
+                    // Calculate the difference between the center of the original image 
-                    graphics.TranslateTransform(rotateAtX - x, rotateAtY - y);
+                    // and the center of the new image.
+                    rotateAtX = Math.Abs(newImage.Width / 2);
+                    rotateAtY = Math.Abs(newImage.Height / 2);
+
+                    // Put the rotation point in the "center" of the image
+                    graphics.TranslateTransform(rotateAtX, rotateAtY);
 
                     // Rotate the image
                     graphics.RotateTransform(angleInDegrees);
 
-                    // Move the image back
-                    graphics.TranslateTransform(-(rotateAtX - x), -(rotateAtY - y));
-
                     // Draw passed in image onto graphics object
-                    graphics.DrawImage(image, new PointF(-x, -y));
+                    graphics.DrawImage(image, new PointF(-previousX, -previousY));
                 }
             }