From 28f65140c4d231fd4ac282bea0f820f8f3eb8699 Mon Sep 17 00:00:00 2001
From: Clemens <fischer.clemens@gmail.com>
Date: Thu, 28 Apr 2022 18:34:30 +0200
Subject: [PATCH] Reworked MapGraticule

---
 MapControl/Shared/MapGraticule.cs      | 159 ++++++++++++++-----------
 MapControl/WPF/MapGraticule.WPF.cs     |  50 ++++----
 MapControl/WinUI/MapGraticule.WinUI.cs |  20 +---
 3 files changed, 116 insertions(+), 113 deletions(-)

diff --git a/MapControl/Shared/MapGraticule.cs b/MapControl/Shared/MapGraticule.cs
index d59c6dcb..3c37466f 100644
--- a/MapControl/Shared/MapGraticule.cs
+++ b/MapControl/Shared/MapGraticule.cs
@@ -28,10 +28,20 @@ namespace MapControl
     {
         private class Label
         {
-            public string LatitudeText { get; set; }
-            public string LongitudeText { get; set; }
-            public Point Position { get; set; }
-            public double Rotation { get; set; }
+            public Label(string latText, string lonText, double x, double y, double rotation)
+            {
+                LatitudeText = latText;
+                LongitudeText = lonText;
+                X = x;
+                Y = y;
+                Rotation = rotation;
+            }
+
+            public string LatitudeText { get; }
+            public string LongitudeText { get; }
+            public double X { get; }
+            public double Y { get; }
+            public double Rotation { get; }
         }
 
         private const double LineInterpolationResolution = 2d;
@@ -96,7 +106,7 @@ namespace MapControl
                 labelFormat, hemisphere, seconds / 3600, seconds / 60 % 60, seconds % 60);
         }
 
-        private void AddLabel(ICollection<Label> labels, Point position, Location location, double? rotation = null)
+        private void AddLabel(ICollection<Label> labels, Location location, Point position, double? rotation = null)
         {
             if (MapProjection.IsValid(position) &&
                 position.X >= 0d && position.X <= ParentMap.RenderSize.Width &&
@@ -104,8 +114,9 @@ namespace MapControl
             {
                 if (!rotation.HasValue)
                 {
-                    var pos = ParentMap.LocationToView(new Location(
-                        location.Latitude, location.Longitude + 10d / PixelPerLongitudeDegree(location)));
+                    location.Longitude += 10d / PixelPerLongitudeDegree(location);
+
+                    var pos = ParentMap.LocationToView(location);
 
                     if (MapProjection.IsValid(pos))
                     {
@@ -115,68 +126,32 @@ namespace MapControl
 
                 if (rotation.HasValue)
                 {
-                    labels.Add(new Label
-                    {
-                        LatitudeText = GetLabelText(location.Latitude, "NS"),
-                        LongitudeText = GetLabelText(Location.NormalizeLongitude(location.Longitude), "EW"),
-                        Position = position,
-                        Rotation = rotation.Value
-                    });
+                    labels.Add(new Label(
+                        GetLabelText(location.Latitude, "NS"),
+                        GetLabelText(Location.NormalizeLongitude(location.Longitude), "EW"),
+                        position.X, position.Y, rotation.Value));
                 }
             }
         }
 
-        private void GetLatitudeRange(double lineDistance, ref double minLatitude, ref double maxLatitude)
+        private ICollection<Label> DrawGraticule(PathFigureCollection figures)
         {
-            var width = ParentMap.RenderSize.Width;
-            var height = ParentMap.RenderSize.Height;
-            var northPole = ParentMap.LocationToView(new Location(90d, 0d));
-            var southPole = ParentMap.LocationToView(new Location(-90d, 0d));
+            var labels = new List<Label>();
 
-            if (northPole.X >= 0d && northPole.Y >= 0d && northPole.X <= width && northPole.Y <= height)
+            figures.Clear();
+
+            SetLineDistance();
+
+            if (ParentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
             {
-                maxLatitude = 90d;
+                DrawCylindricalGraticule(figures, labels);
+            }
+            else
+            {
+                DrawGraticule(figures, labels);
             }
 
-            if (southPole.X >= 0d && southPole.Y >= 0d && southPole.X <= width && southPole.Y <= height)
-            {
-                minLatitude = -90d;
-            }
-
-            if (minLatitude > -90d || maxLatitude < 90d)
-            {
-                var locations = new Location[]
-                {
-                    ParentMap.ViewToLocation(new Point(0d, 0d)),
-                    ParentMap.ViewToLocation(new Point(width / 2d, 0d)),
-                    ParentMap.ViewToLocation(new Point(width, 0d)),
-                    ParentMap.ViewToLocation(new Point(width, height / 2d)),
-                    ParentMap.ViewToLocation(new Point(width, height)),
-                    ParentMap.ViewToLocation(new Point(width / 2d, height)),
-                    ParentMap.ViewToLocation(new Point(0d, height)),
-                    ParentMap.ViewToLocation(new Point(0d, height / 2)),
-                };
-
-                var latitudes = locations.Where(loc => loc != null).Select(loc => loc.Latitude);
-                var south = -90d;
-                var north = 90d;
-
-                if (latitudes.Distinct().Count() >= 2)
-                {
-                    south = latitudes.Min();
-                    north = latitudes.Max();
-                }
-
-                if (minLatitude > -90d)
-                {
-                    minLatitude = Math.Max(Math.Floor(south / lineDistance) * lineDistance, -90d);
-                }
-
-                if (maxLatitude < 90d)
-                {
-                    maxLatitude = Math.Min(Math.Ceiling(north / lineDistance) * lineDistance, 90d);
-                }
-            }
+            return labels;
         }
 
         private void DrawCylindricalGraticule(PathFigureCollection figures, ICollection<Label> labels)
@@ -205,16 +180,13 @@ namespace MapControl
                 {
                     figures.Add(CreateLineFigure(p1, p2));
                 }
-            }
 
-            for (var lat = latLabelStart; lat <= bounds.North; lat += lineDistance)
-            {
-                for (var lon = lonLabelStart; lon <= bounds.East; lon += lineDistance)
+                for (var lat = latLabelStart; lat <= bounds.North; lat += lineDistance)
                 {
                     var location = new Location(lat, lon);
                     var position = ParentMap.LocationToView(location);
 
-                    AddLabel(labels, position, location, ParentMap.ViewTransform.Rotation);
+                    AddLabel(labels, location, position, ParentMap.ViewTransform.Rotation);
                 }
             }
         }
@@ -274,7 +246,7 @@ namespace MapControl
                 if (MapProjection.IsValid(position))
                 {
                     points.Add(position);
-                    AddLabel(labels, position, location);
+                    AddLabel(labels, location, position);
                 }
 
                 for (int j = 0; j < lonSegments; j++)
@@ -291,7 +263,7 @@ namespace MapControl
                         }
                     }
 
-                    AddLabel(labels, position, location);
+                    AddLabel(labels, location, position);
                 }
 
                 if (points.Count >= 2)
@@ -329,6 +301,59 @@ namespace MapControl
             return visible;
         }
 
+        private void GetLatitudeRange(double lineDistance, ref double minLatitude, ref double maxLatitude)
+        {
+            var width = ParentMap.RenderSize.Width;
+            var height = ParentMap.RenderSize.Height;
+            var northPole = ParentMap.LocationToView(new Location(90d, 0d));
+            var southPole = ParentMap.LocationToView(new Location(-90d, 0d));
+
+            if (northPole.X >= 0d && northPole.Y >= 0d && northPole.X <= width && northPole.Y <= height)
+            {
+                maxLatitude = 90d;
+            }
+
+            if (southPole.X >= 0d && southPole.Y >= 0d && southPole.X <= width && southPole.Y <= height)
+            {
+                minLatitude = -90d;
+            }
+
+            if (minLatitude > -90d || maxLatitude < 90d)
+            {
+                var locations = new Location[]
+                {
+                    ParentMap.ViewToLocation(new Point(0d, 0d)),
+                    ParentMap.ViewToLocation(new Point(width / 2d, 0d)),
+                    ParentMap.ViewToLocation(new Point(width, 0d)),
+                    ParentMap.ViewToLocation(new Point(width, height / 2d)),
+                    ParentMap.ViewToLocation(new Point(width, height)),
+                    ParentMap.ViewToLocation(new Point(width / 2d, height)),
+                    ParentMap.ViewToLocation(new Point(0d, height)),
+                    ParentMap.ViewToLocation(new Point(0d, height / 2)),
+                };
+
+                var latitudes = locations.Where(loc => loc != null).Select(loc => loc.Latitude);
+                var south = -90d;
+                var north = 90d;
+
+                if (latitudes.Distinct().Count() >= 2)
+                {
+                    south = latitudes.Min();
+                    north = latitudes.Max();
+                }
+
+                if (minLatitude > -90d)
+                {
+                    minLatitude = Math.Max(Math.Floor(south / lineDistance) * lineDistance, -90d);
+                }
+
+                if (maxLatitude < 90d)
+                {
+                    maxLatitude = Math.Min(Math.Ceiling(north / lineDistance) * lineDistance, 90d);
+                }
+            }
+        }
+
         private static PathFigure CreateLineFigure(Point p1, Point p2)
         {
             var figure = new PathFigure
diff --git a/MapControl/WPF/MapGraticule.WPF.cs b/MapControl/WPF/MapGraticule.WPF.cs
index 492c7afa..275a553a 100644
--- a/MapControl/WPF/MapGraticule.WPF.cs
+++ b/MapControl/WPF/MapGraticule.WPF.cs
@@ -26,49 +26,41 @@ namespace MapControl
 
         protected override void OnRender(DrawingContext drawingContext)
         {
-            var projection = ParentMap?.MapProjection;
-
-            if (projection != null)
+            if (ParentMap != null)
             {
-                var typeface = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch);
-                var pixelsPerDip = VisualTreeHelper.GetDpi(this).PixelsPerDip;
                 var pathGeometry = new PathGeometry();
-                var labels = new List<Label>();
 
-                SetLineDistance();
-
-                if (projection.Type <= MapProjectionType.NormalCylindrical)
-                {
-                    DrawCylindricalGraticule(pathGeometry.Figures, labels);
-                }
-                else
-                {
-                    DrawGraticule(pathGeometry.Figures, labels);
-                }
+                var labels = DrawGraticule(pathGeometry.Figures);
 
                 drawingContext.DrawGeometry(null, CreatePen(), pathGeometry);
 
-                foreach (var label in labels)
+                if (labels.Count > 0)
                 {
-                    var latText = new FormattedText(label.LatitudeText,
-                        CultureInfo.InvariantCulture, FlowDirection.LeftToRight, typeface, FontSize, Foreground, pixelsPerDip);
+                    var typeface = new Typeface(FontFamily, FontStyle, FontWeight, FontStretch);
+                    var pixelsPerDip = VisualTreeHelper.GetDpi(this).PixelsPerDip;
 
-                    var lonText = new FormattedText(label.LongitudeText,
-                        CultureInfo.InvariantCulture, FlowDirection.LeftToRight, typeface, FontSize, Foreground, pixelsPerDip);
+                    foreach (var label in labels)
+                    {
+                        var latText = new FormattedText(label.LatitudeText,
+                            CultureInfo.InvariantCulture, FlowDirection.LeftToRight, typeface, FontSize, Foreground, pixelsPerDip);
 
-                    var x = label.Position.X + StrokeThickness / 2d + 2d;
-                    var y1 = label.Position.Y - StrokeThickness / 2d - latText.Height;
-                    var y2 = label.Position.Y + StrokeThickness / 2d;
+                        var lonText = new FormattedText(label.LongitudeText,
+                            CultureInfo.InvariantCulture, FlowDirection.LeftToRight, typeface, FontSize, Foreground, pixelsPerDip);
 
-                    drawingContext.PushTransform(new RotateTransform(label.Rotation, label.Position.X, label.Position.Y));
-                    drawingContext.DrawText(latText, new Point(x, y1));
-                    drawingContext.DrawText(lonText, new Point(x, y2));
-                    drawingContext.Pop();
+                        var x = label.X + StrokeThickness / 2d + 2d;
+                        var y1 = label.Y - StrokeThickness / 2d - latText.Height;
+                        var y2 = label.Y + StrokeThickness / 2d;
+
+                        drawingContext.PushTransform(new RotateTransform(label.Rotation, label.X, label.Y));
+                        drawingContext.DrawText(latText, new Point(x, y1));
+                        drawingContext.DrawText(lonText, new Point(x, y2));
+                        drawingContext.Pop();
+                    }
                 }
             }
         }
 
-        private static PathFigure CreatePolylineFigure(ICollection<Point> points)
+        private static PathFigure CreatePolylineFigure(IEnumerable<Point> points)
         {
             var figure = new PathFigure
             {
diff --git a/MapControl/WinUI/MapGraticule.WinUI.cs b/MapControl/WinUI/MapGraticule.WinUI.cs
index a71a7c78..3d54bdca 100644
--- a/MapControl/WinUI/MapGraticule.WinUI.cs
+++ b/MapControl/WinUI/MapGraticule.WinUI.cs
@@ -28,21 +28,7 @@ namespace MapControl
 
         protected override void OnViewportChanged(ViewportChangedEventArgs e)
         {
-            var labels = new List<Label>();
-            var pathFigures = ((PathGeometry)path.Data).Figures;
-            
-            pathFigures.Clear();
-
-            SetLineDistance();
-
-            if (ParentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
-            {
-                DrawCylindricalGraticule(pathFigures, labels);
-            }
-            else
-            {
-                DrawGraticule(pathFigures, labels);
-            }
+            var labels = DrawGraticule(((PathGeometry)path.Data).Figures);
 
             if (Children.Count == 0)
             {
@@ -89,7 +75,7 @@ namespace MapControl
 
                 matrix.Translate(StrokeThickness / 2d + 2d, -textBlock.DesiredSize.Height / 2d);
                 matrix.Rotate(label.Rotation);
-                matrix.Translate(label.Position.X, label.Position.Y);
+                matrix.Translate(label.X, label.Y);
 
                 ((MatrixTransform)textBlock.RenderTransform).Matrix = matrix;
 
@@ -104,7 +90,7 @@ namespace MapControl
             base.OnViewportChanged(e);
         }
 
-        private static PathFigure CreatePolylineFigure(ICollection<Point> points)
+        private static PathFigure CreatePolylineFigure(IEnumerable<Point> points)
         {
             var figure = new PathFigure
             {