Merge pull request #145 from obayomy/master

Added wrapper for ClipperOffset algorithm to fix internal exception

Author: JimBobSquarePants

src/ImageSharp.Drawing/Shapes/ClipPathExtensions.cs

@@ -17,6 +17,7 @@ public static class ClipPathExtensions
         /// <param name="shape">The shape.</param>
         /// <param name="holes">The holes.</param>
         /// <returns>Returns a new shape with the holes clipped out of the shape.</returns>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         public static IPath Clip(this IPath shape, IEnumerable<IPath> holes)
         {
             var clipper = new Clipper();
@@ -35,6 +36,7 @@ public static IPath Clip(this IPath shape, IEnumerable<IPath> holes)
         /// <param name="shape">The shape.</param>
         /// <param name="holes">The holes.</param>
         /// <returns>Returns a new shape with the holes clipped out of the shape.</returns>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         public static IPath Clip(this IPath shape, params IPath[] holes)
             => shape.Clip((IEnumerable<IPath>)holes);
     }

src/ImageSharp.Drawing/Shapes/Clipper/clipper.cs

@@ -1,4 +1,4 @@
-// <auto-generated />
+// <auto-generated />
 // not really auto generated but is a code based dependency from https://sourceforge.net/projects/polyclipping/
 // only update is to make everything internal
 /*******************************************************************************
@@ -54,6 +54,7 @@
 
 using System;
 using System.Collections.Generic;
+using ClipperException = SixLabors.ImageSharp.Drawing.PolygonClipper.ClipperException;
 //using System.Text;          //for Int128.AsString() & StringBuilder
 //using System.IO;            //debugging with streamReader & StreamWriter
 //using System.Windows.Forms; //debugging to clipboard
@@ -4986,11 +4987,6 @@ internal void DoRound(int j, int k)
         }
         //------------------------------------------------------------------------------
     }
-
-    class ClipperException : Exception
-    {
-        public ClipperException(string description) : base(description) { }
-    }
     //------------------------------------------------------------------------------
 
-} //end ClipperLib namespace
+} //end ClipperLib namespace

src/ImageSharp.Drawing/Shapes/OutlinePathExtensions.cs

@@ -3,10 +3,8 @@
 
 using System;
 using System.Collections.Generic;
-using System.Linq;
 using System.Numerics;
-using System.Runtime.InteropServices;
-using ClipperLib;
+using SixLabors.ImageSharp.Drawing.PolygonClipper;
 
 namespace SixLabors.ImageSharp.Drawing
 {
@@ -16,7 +14,6 @@ namespace SixLabors.ImageSharp.Drawing
     public static class OutlinePathExtensions
     {
         private const double MiterOffsetDelta = 20;
-        private const float ScalingFactor = 1000.0f;
 
         /// <summary>
         /// Generates a outline of the path with alternating on and off segments based on the pattern.
@@ -25,6 +22,7 @@ public static class OutlinePathExtensions
         /// <param name="width">The final width outline</param>
         /// <param name="pattern">The pattern made of multiples of the width.</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, float[] pattern)
             => path.GenerateOutline(width, new ReadOnlySpan<float>(pattern));
 
@@ -35,6 +33,7 @@ public static IPath GenerateOutline(this IPath path, float width, float[] patter
         /// <param name="width">The final width outline</param>
         /// <param name="pattern">The pattern made of multiples of the width.</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<float> pattern)
             => path.GenerateOutline(width, pattern, false);
 
@@ -46,6 +45,7 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
         /// <param name="pattern">The pattern made of multiples of the width.</param>
         /// <param name="startOff">Weather the first item in the pattern is on or off.</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, float[] pattern, bool startOff)
             => path.GenerateOutline(width, new ReadOnlySpan<float>(pattern), startOff);
 
@@ -57,6 +57,7 @@ public static IPath GenerateOutline(this IPath path, float width, float[] patter
         /// <param name="pattern">The pattern made of multiples of the width.</param>
         /// <param name="startOff">Weather the first item in the pattern is on or off.</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<float> pattern, bool startOff)
             => GenerateOutline(path, width, pattern, startOff, JointStyle.Square, EndCapStyle.Butt);
 
@@ -70,24 +71,18 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
         /// <param name="jointStyle">The style to render the joints.</param>
         /// <param name="patternSectionCapStyle">The style to render between sections of the specified pattern.</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<float> pattern, bool startOff, JointStyle jointStyle = JointStyle.Square, EndCapStyle patternSectionCapStyle = EndCapStyle.Butt)
         {
             if (pattern.Length < 2)
             {
                 return path.GenerateOutline(width, jointStyle: jointStyle);
             }
 
-            JoinType style = Convert(jointStyle);
-            EndType patternSectionCap = Convert(patternSectionCapStyle);
-
             IEnumerable<ISimplePath> paths = path.Flatten();
 
-            var offset = new ClipperOffset()
-            {
-                MiterLimit = MiterOffsetDelta
-            };
-
-            var buffer = new List<IntPoint>(3);
+            var offset = new ClipperOffset(MiterOffsetDelta);
+            var buffer = new List<PointF>();
             foreach (ISimplePath p in paths)
             {
                 bool online = !startOff;
@@ -116,13 +111,13 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
                         float t = targetLength / distToNext;
 
                         Vector2 point = (currentPoint * (1 - t)) + (targetPoint * t);
-                        buffer.Add(currentPoint.ToPoint());
-                        buffer.Add(point.ToPoint());
+                        buffer.Add(currentPoint);
+                        buffer.Add(point);
 
                         // we now inset a line joining
                         if (online)
                         {
-                            offset.AddPath(buffer, style, patternSectionCap);
+                            offset.AddPath(new ReadOnlySpan<PointF>(buffer.ToArray()), jointStyle, patternSectionCapStyle);
                         }
 
                         online = !online;
@@ -137,7 +132,7 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
                     }
                     else if (distToNext <= targetLength)
                     {
-                        buffer.Add(currentPoint.ToPoint());
+                        buffer.Add(currentPoint);
                         currentPoint = targetPoint;
                         i++;
                         targetLength -= distToNext;
@@ -148,16 +143,16 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
                 {
                     if (p.IsClosed)
                     {
-                        buffer.Add(points[0].ToPoint());
+                        buffer.Add(points[0]);
                     }
                     else
                     {
-                        buffer.Add(points[points.Length - 1].ToPoint());
+                        buffer.Add(points[points.Length - 1]);
                     }
 
                     if (online)
                     {
-                        offset.AddPath(buffer, style, patternSectionCap);
+                        offset.AddPath(new ReadOnlySpan<PointF>(buffer.ToArray()), jointStyle, patternSectionCapStyle);
                     }
 
                     online = !online;
@@ -168,7 +163,7 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
                 }
             }
 
-            return ExecuteOutliner(width, offset);
+            return offset.Execute(width);
         }
 
         /// <summary>
@@ -177,6 +172,7 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
         /// <param name="path">the path to outline</param>
         /// <param name="width">The final width outline</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width) => GenerateOutline(path, width, JointStyle.Square, EndCapStyle.Butt);
 
         /// <summary>
@@ -187,69 +183,13 @@ public static IPath GenerateOutline(this IPath path, float width, ReadOnlySpan<f
         /// <param name="jointStyle">The style to render the joints.</param>
         /// <param name="endCapStyle">The style to render the end caps of open paths (ignored on closed paths).</param>
         /// <returns>A new path representing the outline.</returns>
+        /// <exception cref="ClipperException">Couldn't calculate offset.</exception>
         public static IPath GenerateOutline(this IPath path, float width, JointStyle jointStyle = JointStyle.Square, EndCapStyle endCapStyle = EndCapStyle.Square)
         {
-            var offset = new ClipperOffset()
-            {
-                MiterLimit = MiterOffsetDelta
-            };
-
-            JoinType style = Convert(jointStyle);
-            EndType openEndCapStyle = Convert(endCapStyle);
-
-            // Pattern can be applied to the path by cutting it into segments
-            IEnumerable<ISimplePath> paths = path.Flatten();
-            foreach (ISimplePath p in paths)
-            {
-                ReadOnlySpan<Vector2> vectors = MemoryMarshal.Cast<PointF, Vector2>(p.Points.Span);
-                var points = new List<IntPoint>(vectors.Length);
-                foreach (Vector2 v in vectors)
-                {
-                    points.Add(new IntPoint(v.X * ScalingFactor, v.Y * ScalingFactor));
-                }
-
-                EndType type = p.IsClosed ? EndType.etClosedLine : openEndCapStyle;
-
-                offset.AddPath(points, style, type);
-            }
-
-            return ExecuteOutliner(width, offset);
-        }
-
-        private static ComplexPolygon ExecuteOutliner(float width, ClipperOffset offset)
-        {
-            var tree = new List<List<IntPoint>>();
-            offset.Execute(ref tree, width * ScalingFactor / 2);
-            var polygons = new List<Polygon>();
-            foreach (List<IntPoint> pt in tree)
-            {
-                PointF[] points = pt.Select(p => new PointF(p.X / ScalingFactor, p.Y / ScalingFactor)).ToArray();
-                polygons.Add(new Polygon(new LinearLineSegment(points)));
-            }
+            var offset = new ClipperOffset(MiterOffsetDelta);
+            offset.AddPath(path, jointStyle, endCapStyle);
 
-            return new ComplexPolygon(polygons.ToArray());
+            return offset.Execute(width);
         }
-
-        private static IntPoint ToPoint(this PointF vector)
-            => new IntPoint(vector.X * ScalingFactor, vector.Y * ScalingFactor);
-
-        private static IntPoint ToPoint(this Vector2 vector)
-            => new IntPoint(vector.X * ScalingFactor, vector.Y * ScalingFactor);
-
-        private static JoinType Convert(JointStyle style)
-            => style switch
-            {
-                JointStyle.Round => JoinType.jtRound,
-                JointStyle.Miter => JoinType.jtMiter,
-                _ => JoinType.jtSquare,
-            };
-
-        private static EndType Convert(EndCapStyle style)
-            => style switch
-            {
-                EndCapStyle.Round => EndType.etOpenRound,
-                EndCapStyle.Square => EndType.etOpenSquare,
-                _ => EndType.etOpenButt,
-            };
     }
 }

src/ImageSharp.Drawing/Shapes/PolygonClipper/Clipper.cs

@@ -1,4 +1,4 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
@@ -11,7 +11,7 @@ namespace SixLabors.ImageSharp.Drawing.PolygonClipper
     /// <summary>
     /// Library to clip polygons.
     /// </summary>
-    public class Clipper
+    internal class Clipper
     {
         private const float ScalingFactor = 1000.0f;
 
@@ -42,6 +42,7 @@ public Clipper(params ClippablePath[] shapes)
         /// <returns>
         /// Returns the <see cref="IPath" /> array containing the converted polygons.
         /// </returns>
+        /// <exception cref="ClipperException">GenerateClippedShapes: Open paths have been disabled.</exception>
         public IPath[] GenerateClippedShapes()
         {
             var results = new List<PolyNode>();
@@ -79,12 +80,10 @@ public IPath[] GenerateClippedShapes()
         /// Adds the paths.
         /// </summary>
         /// <param name="paths">The paths.</param>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         public void AddPaths(ClippablePath[] paths)
         {
-            if (paths == null)
-            {
-                throw new ArgumentNullException(nameof(paths));
-            }
+            Guard.NotNull(paths, nameof(paths));
 
             for (int i = 0; i < paths.Length; i++)
             {
@@ -99,12 +98,10 @@ public void AddPaths(ClippablePath[] paths)
         /// </summary>
         /// <param name="paths">The paths.</param>
         /// <param name="clippingType">The clipping type.</param>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         public void AddPaths(IEnumerable<IPath> paths, ClippingType clippingType)
         {
-            if (paths is null)
-            {
-                throw new ArgumentNullException(nameof(paths));
-            }
+            Guard.NotNull(paths, nameof(paths));
 
             foreach (IPath p in paths)
             {
@@ -117,12 +114,10 @@ public void AddPaths(IEnumerable<IPath> paths, ClippingType clippingType)
         /// </summary>
         /// <param name="path">The path.</param>
         /// <param name="clippingType">The clipping type.</param>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         public void AddPath(IPath path, ClippingType clippingType)
         {
-            if (path is null)
-            {
-                throw new ArgumentNullException(nameof(path));
-            }
+            Guard.NotNull(path, nameof(path));
 
             foreach (ISimplePath p in path.Flatten())
             {
@@ -135,7 +130,7 @@ public void AddPath(IPath path, ClippingType clippingType)
         /// </summary>
         /// <param name="path">The path.</param>
         /// <param name="clippingType">Type of the poly.</param>
-        /// <exception cref="ClipperException">AddPath: Open paths have been disabled.</exception>
+        /// <exception cref="ClipperException">Open paths have been disabled.</exception>
         internal void AddPath(ISimplePath path, ClippingType clippingType)
         {
             ReadOnlySpan<PointF> vectors = path.Points.Span;
@@ -153,4 +148,4 @@ internal void AddPath(ISimplePath path, ClippingType clippingType)
             }
         }
     }
-}
+}

src/ImageSharp.Drawing/Shapes/PolygonClipper/ClipperException.cs

@@ -1,23 +1,22 @@
-// Copyright (c) Six Labors.
+// Copyright (c) Six Labors.
 // Licensed under the Apache License, Version 2.0.
 
 using System;
 
 namespace SixLabors.ImageSharp.Drawing.PolygonClipper
 {
     /// <summary>
-    /// Clipper Exception
+    /// The exception that is thrown when an error occurs clipping a polygon.
     /// </summary>
-    /// <seealso cref="System.Exception" />
-    internal class ClipperException : Exception
+    public class ClipperException : Exception
     {
         /// <summary>
         /// Initializes a new instance of the <see cref="ClipperException"/> class.
         /// </summary>
-        /// <param name="description">The description.</param>
-        public ClipperException(string description)
-            : base(description)
+        /// <param name="message">The message that describes the error.</param>
+        public ClipperException(string message)
+            : base(message)
         {
         }
     }
-}
+}