MapPolypoint implementation

MapControl/Avalonia/MapPolypoint.Avalonia.cs

@@ -51,31 +51,39 @@ namespace MapControl
 
         protected void UpdateData(IEnumerable<Location> locations, bool closed)
         {
-            var pathFigure = new PathFigure();
+            var pathFigures = new PathFigures();
 
-            if (ParentMap != null && locations?.Count() >= 2)
+            if (ParentMap != null && locations != null)
             {
-                var longitudeOffset = GetLongitudeOffset(Location ?? locations.First());
+                var longitudeOffset = GetLongitudeOffset(Location ?? locations.FirstOrDefault());
 
-                AddPolylinePoints(pathFigure, locations, longitudeOffset, closed);
+                AddPolylinePoints(pathFigures, locations, longitudeOffset, closed);
             }
 
-            ((PathGeometry)Data).Figures = new PathFigures { pathFigure };
+            ((PathGeometry)Data).Figures = pathFigures;
 
-            InvalidateGeometry(); // ignores an empty PathGeometry.Figures collection
+            InvalidateGeometry();
         }
 
-        private void AddPolylinePoints(PathFigure pathFigure, IEnumerable<Location> locations, double longitudeOffset, bool closed)
+        private void AddPolylinePoints(PathFigures pathFigures, IEnumerable<Location> locations, double longitudeOffset, bool closed)
         {
             var points = locations
                 .Select(location => LocationToView(location, longitudeOffset))
                 .Where(point => point.HasValue)
                 .Select(point => point.Value);
 
-            pathFigure.StartPoint = points.First();
+            if (points.Any())
-            pathFigure.Segments.Add(new PolyLineSegment(points.Skip(1)));
+            {
-            pathFigure.IsClosed = closed;
+                var figure = new PathFigure
-            pathFigure.IsFilled = true;
+                {
+                    StartPoint = points.First(),
+                    IsClosed = closed,
+                    IsFilled = true
+                };
+
+                figure.Segments.Add(new PolyLineSegment(points.Skip(1)));
+                pathFigures.Add(figure);
+            }
         }
     }
 }

MapControl/WPF/MapPolypoint.WPF.cs

@@ -60,9 +60,9 @@ namespace MapControl
         {
             using (var context = ((StreamGeometry)Data).Open())
             {
-                if (ParentMap != null && locations?.Count() >= 2)
+                if (ParentMap != null && locations != null)
                 {
-                    var longitudeOffset = GetLongitudeOffset(Location ?? locations.First());
+                    var longitudeOffset = GetLongitudeOffset(Location ?? locations.FirstOrDefault());
 
                     AddPolylinePoints(context, locations, longitudeOffset, closed);
                 }
@@ -77,7 +77,7 @@ namespace MapControl
                 {
                     var longitudeOffset = GetLongitudeOffset(Location);
 
-                    foreach (var polygon in polygons.Where(p => p?.Count() >= 2))
+                    foreach (var polygon in polygons)
                     {
                         AddPolylinePoints(context, polygon, longitudeOffset, true);
                     }
@@ -92,8 +92,11 @@ namespace MapControl
                 .Where(point => point.HasValue)
                 .Select(point => point.Value);
 
+            if (points.Any())
+            {
                 context.BeginFigure(points.First(), true, closed);
                 context.PolyLineTo(points.Skip(1).ToList(), true, true);
             }
         }
+    }
 }

MapControl/WinUI/MapPolypoint.WinUI.cs

@@ -2,7 +2,6 @@
 // Copyright © 2024 Clemens Fischer
 // Licensed under the Microsoft Public License (Ms-PL)
 
-using System;
 using System.Collections;
 using System.Collections.Generic;
 using System.Collections.Specialized;
@@ -62,9 +61,9 @@ namespace MapControl
             var pathFigures = ((PathGeometry)Data).Figures;
             pathFigures.Clear();
 
-            if (ParentMap != null && locations?.Count() >= 2)
+            if (ParentMap != null && locations != null)
             {
-                var longitudeOffset = GetLongitudeOffset(Location ?? locations.First());
+                var longitudeOffset = GetLongitudeOffset(Location ?? locations.FirstOrDefault());
 
                 AddPolylinePoints(pathFigures, locations, longitudeOffset, closed);
             }
@@ -77,12 +76,12 @@ namespace MapControl
                 .Where(point => point.HasValue)
                 .Select(point => point.Value);
 
-            if (closed)
+            if (points.Any())
             {
                 var figure = new PathFigure
                 {
                     StartPoint = points.First(),
-                    IsClosed = true,
+                    IsClosed = closed,
                     IsFilled = true
                 };
 
@@ -96,133 +95,6 @@ namespace MapControl
                 figure.Segments.Add(polyline);
                 pathFigures.Add(figure);
             }
-            else
-            {
-                PathFigure figure = null;
-                PolyLineSegment polyline = null;
-                var viewport = new Rect(0, 0, ParentMap.RenderSize.Width, ParentMap.RenderSize.Height);
-                var pointList = points.ToList();
-
-                for (int i = 1; i < pointList.Count; i++)
-                {
-                    var p1 = pointList[i - 1];
-                    var p2 = pointList[i];
-                    var inside = GetIntersections(ref p1, ref p2, viewport);
-
-                    if (inside)
-                    {
-                        if (figure == null)
-                        {
-                            figure = new PathFigure
-                            {
-                                StartPoint = p1,
-                                IsClosed = false,
-                                IsFilled = true
-                            };
-
-                            polyline = new PolyLineSegment();
-                            figure.Segments.Add(polyline);
-                            pathFigures.Add(figure);
-                        }
-
-                        polyline.Points.Add(p2);
-                    }
-
-                    if (!inside || p2 != pointList[i])
-                    {
-                        figure = null;
-                    }
-                }
-            }
-        }
-
-        /// <summary>
-        /// Calculates the potential intersections of a line segment given by (p1,p2) with a rectangle.
-        /// Updates either p1, p2, or both with any found intersection and returns a value that indicates
-        /// whether the segment intersects or lies inside the rectangle.
-        /// </summary>
-        private static bool GetIntersections(ref Point p1, ref Point p2, Rect rect)
-        {
-            if (rect.Contains(p1) && rect.Contains(p2))
-            {
-                return true;
-            }
-
-            var topLeft = new Point(rect.X, rect.Y);
-            var topRight = new Point(rect.X + rect.Width, rect.Y);
-            var bottomLeft = new Point(rect.X, rect.Y + rect.Height);
-            var bottomRight = new Point(rect.X + rect.Width, rect.Y + rect.Height);
-            var numIntersections = 0;
-
-            if (GetIntersection(ref p1, ref p2, topLeft, bottomLeft, p => p.X <= rect.X)) // left edge
-            {
-                numIntersections++;
-            }
-
-            if (GetIntersection(ref p1, ref p2, topLeft, topRight, p => p.Y <= rect.Y)) // top edge
-            {
-                numIntersections++;
-            }
-
-            if (numIntersections < 2 &&
-                GetIntersection(ref p1, ref p2, topRight, bottomRight, p => p.X >= rect.X + rect.Width)) // right edge
-            {
-                numIntersections++;
-            }
-
-            if (numIntersections < 2 &&
-                GetIntersection(ref p1, ref p2, bottomLeft, bottomRight, p => p.Y >= rect.Y + rect.Height)) // bottom edge
-            {
-                numIntersections++;
-            }
-
-            return numIntersections > 0;
-        }
-
-        private static bool GetIntersection(ref Point p1, ref Point p2, Point p3, Point p4, Predicate<Point> predicate)
-        {
-            var intersection = GetIntersection(p1, p2, p3, p4);
-
-            if (!intersection.HasValue)
-            {
-                return false;
-            }
-
-            if (predicate(p1))
-            {
-                p1 = intersection.Value;
-            }
-            else
-            {
-                p2 = intersection.Value;
-            }
-
-            return true;
-        }
-
-        /// <summary>
-        /// Returns the intersection point of two line segments given by (p1,p2) and (p3,p4),
-        /// or null if no intersection exists. See https://stackoverflow.com/a/1968345.
-        /// </summary>
-        private static Point? GetIntersection(Point p1, Point p2, Point p3, Point p4)
-        {
-            var x12 = p2.X - p1.X;
-            var y12 = p2.Y - p1.Y;
-            var x34 = p4.X - p3.X;
-            var y34 = p4.Y - p3.Y;
-            var x13 = p3.X - p1.X;
-            var y13 = p3.Y - p1.Y;
-
-            var d = x12 * y34 - x34 * y12;
-            var s = (x13 * y12 - y13 * x12) / d;
-            var t = (x13 * y34 - y13 * x34) / d;
-
-            if (s >= 0d && s <= 1d && t >= 0d && t <= 1d)
-            {
-                return new Point(p1.X + t * x12, p1.Y + t * y12);
-            }
-
-            return null;
         }
     }
 }