MapPanel longitude coercion

MapControl/Avalonia/MapControl.Avalonia.csproj

@@ -12,7 +12,6 @@
 
     <ItemGroup>
         <Compile Include="..\Shared\*.cs" />
-        <Compile Remove="..\Shared\ViewTransform.cs" />
     </ItemGroup>
 
     <ItemGroup>

MapControl/Avalonia/ViewTransform.Avalonia.cs

@@ -2,47 +2,10 @@
 // Copyright © 2024 Clemens Fischer
 // Licensed under the Microsoft Public License (Ms-PL)
 
-using System;
-
 namespace MapControl
 {
-    /// <summary>
+    public partial class ViewTransform
-    /// Defines the transformation between projected map coordinates in meters
-    /// and view coordinates in pixels.
-    /// </summary>
-    public class ViewTransform
     {
-        public static double ZoomLevelToScale(double zoomLevel)
-        {
-            return 256d * Math.Pow(2d, zoomLevel) / (360d * MapProjection.Wgs84MeterPerDegree);
-        }
-
-        public static double ScaleToZoomLevel(double scale)
-        {
-            return Math.Log(scale * 360d * MapProjection.Wgs84MeterPerDegree / 256d, 2d);
-        }
-
-        /// <summary>
-        /// Gets the scaling factor from projected map coordinates to view coordinates,
-        /// as pixels per meter.
-        /// </summary>
-        public double Scale { get; private set; }
-
-        /// <summary>
-        /// Gets the rotation angle of the transform matrix.
-        /// </summary>
-        public double Rotation { get; private set; }
-
-        /// <summary>
-        /// Gets the transform matrix from projected map coordinates to view coordinates.
-        /// </summary>
-        public Matrix MapToViewMatrix { get; private set; }
-
-        /// <summary>
-        /// Gets the transform matrix from view coordinates to projected map coordinates.
-        /// </summary>
-        public Matrix ViewToMapMatrix { get; private set; }
-
         /// <summary>
         /// Initializes a ViewTransform from a map center point in projected coordinates,
         /// a view conter point, a scaling factor from projected coordinates to view coordinates
@@ -62,31 +25,6 @@ namespace MapControl
             ViewToMapMatrix = MapToViewMatrix.Invert();
         }
 
-        /// <summary>
-        /// Transforms a Point from projected map coordinates to view coordinates.
-        /// </summary>
-        public Point MapToView(Point point)
-        {
-            return MapToViewMatrix.Transform(point);
-        }
-
-        /// <summary>
-        /// Transforms a Point from view coordinates to projected map coordinates.
-        /// </summary>
-        public Point ViewToMap(Point point)
-        {
-            return ViewToMapMatrix.Transform(point);
-        }
-
-        /// <summary>
-        /// Transform relative to absolute map scale. Returns horizontal and vertical
-        /// scaling factors from meters to view coordinates.
-        /// </summary>
-        public Point GetMapScale(Point relativeScale)
-        {
-            return new Point(Scale * relativeScale.X, Scale * relativeScale.Y);
-        }
-
         /// <summary>
         /// Gets a transform Matrix from meters to view coordinates for a relative map scale.
         /// </summary>

MapControl/Shared/BoundingBox.cs

@@ -17,7 +17,7 @@ namespace MapControl
 #endif
     public class BoundingBox
     {
-        public BoundingBox()
+        protected BoundingBox()
         {
         }
 
@@ -34,15 +34,27 @@ namespace MapControl
         {
         }
 
-        public double South { get; }
+        public double South { get; private set; }
-        public double North { get; }
+        public double North { get; private set; }
-        public double West { get; }
+        public double West { get; private set; }
-        public double East { get; }
+        public double East { get; private set; }
 
         public virtual double Width => East - West;
         public virtual double Height => North - South;
 
-        public virtual Location Center => new Location((South + North) / 2d, (West + East) / 2d);
+        public virtual Location Center
+        {
+            get => new Location((South + North) / 2d, (West + East) / 2d);
+            set
+            {
+                var latOffset = value.Latitude - (South + North) / 2d;
+                var lonOffset = value.Longitude - (West + East) / 2d;
+                South += latOffset;
+                North += latOffset;
+                West += lonOffset;
+                East += lonOffset;
+            }
+        }
 
         /// <summary>
         /// Creates a BoundingBox instance from a string containing a comma-separated sequence of four floating point numbers.

MapControl/Shared/CenteredBoundingBox.cs

@@ -8,19 +8,15 @@ namespace MapControl
 {
     public class CenteredBoundingBox : BoundingBox
     {
-        private readonly Location center;
+        public CenteredBoundingBox(Location center, double width, double height)
-        private readonly double width;
-        private readonly double height;
-
-        public CenteredBoundingBox(Location c, double w, double h)
         {
-            center = c;
+            Center = center;
-            width = Math.Max(w, 0d);
+            Width = Math.Max(width, 0d);
-            height = Math.Max(h, 0d);
+            Height = Math.Max(height, 0d);
         }
 
-        public override Location Center => center;
+        public override Location Center { get; set; }
-        public override double Width => width;
+        public override double Width { get; }
-        public override double Height => height;
+        public override double Height { get; }
     }
 }

MapControl/Shared/MapBase.cs

@@ -31,6 +31,10 @@ namespace MapControl
     /// </summary>
     public partial class MapBase : MapPanel
     {
+        public static double ZoomLevelToScale(double zoomLevel) => 256d * Math.Pow(2d, zoomLevel) / (360d * MapProjection.Wgs84MeterPerDegree);
+
+        public static double ScaleToZoomLevel(double scale) => Math.Log(scale * 360d * MapProjection.Wgs84MeterPerDegree / 256d, 2d);
+
         public static TimeSpan ImageFadeDuration { get; set; } = TimeSpan.FromSeconds(0.1);
 
         public static readonly DependencyProperty AnimationDurationProperty =
@@ -361,7 +365,7 @@ namespace MapControl
                 {
                     var scale = Math.Min(ActualWidth / rect.Value.Width, ActualHeight / rect.Value.Height);
 
-                    TargetZoomLevel = ViewTransform.ScaleToZoomLevel(scale);
+                    TargetZoomLevel = ScaleToZoomLevel(scale);
                     TargetCenter = targetCenter;
                     TargetHeading = 0d;
                 }
@@ -497,7 +501,7 @@ namespace MapControl
         private void UpdateTransform(bool resetTransformCenter = false, bool projectionChanged = false)
         {
             var transformCenterChanged = false;
-            var viewScale = ViewTransform.ZoomLevelToScale(ZoomLevel);
+            var viewScale = ZoomLevelToScale(ZoomLevel);
             var projection = MapProjection;
 
             projection.Center = ProjectionCenter ?? Center;

MapControl/Shared/MapPanel.cs

@@ -189,66 +189,53 @@ namespace MapControl
 
         protected Point? GetViewPosition(Location location)
         {
-            var position = parentMap.LocationToView(location);
+            if (parentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
-
-            if (parentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical &&
-                position.HasValue &&
-                !InsideViewport(position.Value))
             {
-                position = parentMap.LocationToView(
+                var longitude = parentMap.CoerceLongitude(location.Longitude);
-                    new Location(location.Latitude, parentMap.CoerceLongitude(location.Longitude)));
+
+                if (longitude != location.Longitude)
+                {
+                    location = new Location(location.Latitude, longitude);
+                }
             }
 
-            return position;
+            return parentMap.LocationToView(location);
         }
 
         protected ViewRect? GetViewRect(BoundingBox boundingBox)
         {
-            var mapRect = parentMap.MapProjection.BoundingBoxToMap(boundingBox);
+            if (parentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
-
-            if (!mapRect.HasValue)
             {
-                return null;
+                var center = boundingBox.Center;
+                var longitude = parentMap.CoerceLongitude(center.Longitude);
+
+                if (longitude != center.Longitude)
+                {
+                    boundingBox.Center = new Location(center.Latitude, longitude);
+                }
             }
 
+            var mapRect = parentMap.MapProjection.BoundingBoxToMap(boundingBox);
+
+            if (mapRect.HasValue)
+            {
                 return GetViewRect(mapRect.Value);
             }
 
+            return null;
+        }
+
         protected ViewRect GetViewRect(Rect mapRect)
         {
+            var transform = parentMap.ViewTransform;
             var center = new Point(mapRect.X + mapRect.Width / 2d, mapRect.Y + mapRect.Height / 2d);
-            var position = parentMap.ViewTransform.MapToView(center);
+            var position = transform.MapToView(center);
-            var projection = parentMap.MapProjection;
+            var width = mapRect.Width * transform.Scale;
-
+            var height = mapRect.Height * transform.Scale;
-            if (projection.Type <= MapProjectionType.NormalCylindrical &&
-                !InsideViewport(position))
-            {
-                var location = projection.MapToLocation(center);
-
-                if (location != null)
-                {
-                    var pos = parentMap.LocationToView(
-                        new Location(location.Latitude, parentMap.CoerceLongitude(location.Longitude)));
-
-                    if (pos.HasValue)
-                    {
-                        position = pos.Value;
-                    }
-                }
-            }
-
-            var width = mapRect.Width * parentMap.ViewTransform.Scale;
-            var height = mapRect.Height * parentMap.ViewTransform.Scale;
             var x = position.X - width / 2d;
             var y = position.Y - height / 2d;
 
-            return new ViewRect(x, y, width, height, parentMap.ViewTransform.Rotation);
+            return new ViewRect(x, y, width, height, transform.Rotation);
-        }
-
-        private bool InsideViewport(Point point)
-        {
-            return point.X >= 0d && point.X <= parentMap.ActualWidth
-                && point.Y >= 0d && point.Y <= parentMap.ActualHeight;
         }
 
         private void ArrangeChildElement(FrameworkElement element, Size panelSize)
@@ -263,7 +250,10 @@ namespace MapControl
 
                 if (GetAutoCollapse(element))
                 {
-                    SetVisible(element, position.HasValue && InsideViewport(position.Value));
+                    SetVisible(element,
+                        position.HasValue &&
+                        position.Value.X >= 0d && position.Value.X <= parentMap.ActualWidth &&
+                        position.Value.Y >= 0d && position.Value.Y <= parentMap.ActualHeight);
                 }
 
                 if (position.HasValue)

MapControl/Shared/MapPath.cs

@@ -4,13 +4,10 @@
 
 #if WPF
 using System.Windows;
-using System.Windows.Media;
 #elif UWP
 using Windows.UI.Xaml;
-using Windows.UI.Xaml.Media;
 #elif WINUI
 using Microsoft.UI.Xaml;
-using Microsoft.UI.Xaml.Media;
 #endif
 
 namespace MapControl
@@ -79,6 +76,18 @@ namespace MapControl
             MapPanel.SetLocation(this, Location);
         }
 
+        protected double GetLongitudeOffset(Location location)
+        {
+            var longitudeOffset = 0d;
+
+            if (location != null && parentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
+            {
+                longitudeOffset = parentMap.CoerceLongitude(location.Longitude) - location.Longitude;
+            }
+
+            return longitudeOffset;
+        }
+
         protected Point? LocationToMap(Location location, double longitudeOffset)
         {
             if (longitudeOffset != 0d)
@@ -107,31 +116,12 @@ namespace MapControl
         {
             var point = LocationToMap(location, longitudeOffset);
 
-            if (!point.HasValue)
+            if (point.HasValue)
             {
-                return null;
+                point = parentMap.ViewTransform.MapToView(point.Value);
             }
 
-            return parentMap.ViewTransform.MapToView(point.Value);
+            return point;
-        }
-
-        protected double GetLongitudeOffset(Location location)
-        {
-            var longitudeOffset = 0d;
-
-            if (location != null && parentMap.MapProjection.Type <= MapProjectionType.NormalCylindrical)
-            {
-                var point = parentMap.LocationToView(location);
-
-                if (point.HasValue &&
-                    (point.Value.X < 0d || point.Value.X > parentMap.ActualWidth ||
-                     point.Value.Y < 0d || point.Value.Y > parentMap.ActualHeight))
-                {
-                    longitudeOffset = parentMap.CoerceLongitude(location.Longitude) - location.Longitude;
-                }
-            }
-
-            return longitudeOffset;
         }
     }
 }

MapControl/Shared/MapTileLayer.cs

@@ -156,7 +156,7 @@ namespace MapControl
                 //
                 var tileMatrixOrigin = new Point(TileSize * TileMatrix.XMin, TileSize * TileMatrix.YMin);
 
-                var tileMatrixScale = ViewTransform.ZoomLevelToScale(TileMatrix.ZoomLevel);
+                var tileMatrixScale = MapBase.ZoomLevelToScale(TileMatrix.ZoomLevel);
 
                 ((MatrixTransform)RenderTransform).Matrix =
                     ParentMap.ViewTransform.GetTileLayerTransform(tileMatrixScale, MapTopLeft, tileMatrixOrigin);
@@ -169,7 +169,7 @@ namespace MapControl
             //
             var tileMatrixZoomLevel = (int)Math.Floor(ParentMap.ZoomLevel - ZoomLevelOffset + 0.001);
 
-            var tileMatrixScale = ViewTransform.ZoomLevelToScale(tileMatrixZoomLevel);
+            var tileMatrixScale = MapBase.ZoomLevelToScale(tileMatrixZoomLevel);
 
             // Bounds in tile pixels from view size.
             //

MapControl/Shared/ViewTransform.cs

@@ -2,7 +2,6 @@
 // Copyright © 2024 Clemens Fischer
 // Licensed under the Microsoft Public License (Ms-PL)
 
-using System;
 #if WPF
 using System.Windows;
 using System.Windows.Media;
@@ -18,18 +17,8 @@ namespace MapControl
     /// Defines the transformation between projected map coordinates in meters
     /// and view coordinates in pixels.
     /// </summary>
-    public class ViewTransform
+    public partial class ViewTransform
     {
-        public static double ZoomLevelToScale(double zoomLevel)
-        {
-            return 256d * Math.Pow(2d, zoomLevel) / (360d * MapProjection.Wgs84MeterPerDegree);
-        }
-
-        public static double ScaleToZoomLevel(double scale)
-        {
-            return Math.Log(scale * 360d * MapProjection.Wgs84MeterPerDegree / 256d, 2d);
-        }
-
         /// <summary>
         /// Gets the scaling factor from projected map coordinates to view coordinates,
         /// as pixels per meter.
@@ -51,6 +40,32 @@ namespace MapControl
         /// </summary>
         public Matrix ViewToMapMatrix { get; private set; }
 
+        /// <summary>
+        /// Transforms a Point from projected map coordinates to view coordinates.
+        /// </summary>
+        public Point MapToView(Point point)
+        {
+            return MapToViewMatrix.Transform(point);
+        }
+
+        /// <summary>
+        /// Transforms a Point from view coordinates to projected map coordinates.
+        /// </summary>
+        public Point ViewToMap(Point point)
+        {
+            return ViewToMapMatrix.Transform(point);
+        }
+
+        /// <summary>
+        /// Transform relative to absolute map scale. Returns horizontal and vertical
+        /// scaling factors from meters to view coordinates.
+        /// </summary>
+        public Point GetMapScale(Point relativeScale)
+        {
+            return new Point(Scale * relativeScale.X, Scale * relativeScale.Y);
+        }
+
+#if WPF || UWP || WINUI
         /// <summary>
         /// Initializes a ViewTransform from a map center point in projected coordinates,
         /// a view conter point, a scaling factor from projected coordinates to view coordinates
@@ -72,30 +87,6 @@ namespace MapControl
             ViewToMapMatrix = transform;
         }
 
-        /// <summary>
-        /// Transforms a Point from projected map coordinates to view coordinates.
-        /// </summary>
-        public Point MapToView(Point point)
-        {
-            return MapToViewMatrix.Transform(point);
-        }
-
-        /// <summary>
-        /// Transforms a Point from view coordinates to projected map coordinates.
-        /// </summary>
-        public Point ViewToMap(Point point)
-        {
-            return ViewToMapMatrix.Transform(point);
-        }
-
-        /// <summary>
-        /// Gets scaling factors from meters to view coordinates for a relative map scale.
-        /// </summary>
-        public Point GetMapScale(Point relativeScale)
-        {
-            return new Point(Scale * relativeScale.X, Scale * relativeScale.Y);
-        }
-
         /// <summary>
         /// Gets a transform Matrix from meters to view coordinates for a relative map scale.
         /// </summary>
@@ -170,5 +161,6 @@ namespace MapControl
 
             return transform;
         }
+#endif
     }
 }