Improved MapProjection.Center handling

MapControl/Shared/MapBase.cs

@@ -734,7 +734,10 @@ namespace MapControl
             var viewScale = ViewTransform.ZoomLevelToScale(ZoomLevel);
             var projection = MapProjection;
 
+            if (projection.Type == MapProjectionType.Azimuthal)
+            {
                 projection.Center = ProjectionCenter ?? Center;
+            }
 
             var mapCenter = projection.LocationToMap(transformCenter ?? Center);
 
@@ -767,7 +770,11 @@ namespace MapControl
                         {
                             ResetTransformCenter();
 
-                            projection.Center = ProjectionCenter ?? center;
+                            if (projection.Type == MapProjectionType.Azimuthal)
+                            {
+                                projection.Center = ProjectionCenter ?? Center;
+                            }
+
                             mapCenter = projection.LocationToMap(center);
 
                             if (MapProjection.IsValid(mapCenter))

MapControl/Shared/MapProjection.cs

@@ -44,7 +44,7 @@ namespace MapControl
         public string CrsId { get; protected set; } = string.Empty;
 
         /// <summary>
-        /// Gets or sets the projection center.
+        /// Gets or sets an optional projection center.
         /// </summary>
         public Location Center { get; set; } = new Location();
 

MapControl/WPF/MapGraticule.WPF.cs

@@ -137,20 +137,30 @@ namespace MapControl
             var latPoints = latSegments * interpolationCount;
 
             var centerLon = Math.Round(ParentMap.Center.Longitude / lineDistance) * lineDistance;
+            var westLimit = centerLon - 180d;
+            var eastLimit = centerLon + 180d;
+
+            if (ParentMap.MapProjection.Type == MapProjectionType.TransverseCylindrical)
+            {
+                westLimit = ParentMap.MapProjection.Center.Longitude - 15d;
+                eastLimit = ParentMap.MapProjection.Center.Longitude + 15d;
+                westLimit = Math.Floor(westLimit / lineDistance) * lineDistance;
+                eastLimit = Math.Ceiling(eastLimit / lineDistance) * lineDistance;
+            }
+
             var minLon = centerLon - lineDistance;
             var maxLon = centerLon + lineDistance;
-            var lonRange = ParentMap.MapProjection.Type == MapProjectionType.TransverseCylindrical ? 15d : 180d;
 
             if (DrawMeridian(path.Figures, centerLon, minLat, interpolationDistance, latPoints))
             {
                 while (DrawMeridian(path.Figures, minLon, minLat, interpolationDistance, latPoints) &&
-                    minLon > centerLon - lonRange)
+                    minLon > westLimit)
                 {
                     minLon -= lineDistance;
                 }
 
                 while (DrawMeridian(path.Figures, maxLon, minLat, interpolationDistance, latPoints) &&
-                    maxLon <= centerLon + lonRange)
+                    maxLon < eastLimit)
                 {
                     maxLon += lineDistance;
                 }

MapProjections/Shared/GeoApiProjection.cs

@@ -25,6 +25,7 @@ namespace MapControl.Projections
     public class GeoApiProjection : MapProjection
     {
         private ICoordinateSystem coordinateSystem;
+        private Location center;
         private double scaleFactor;
         private string bboxFormat;
 
@@ -100,6 +101,10 @@ namespace MapControl.Projections
                         Type = MapProjectionType.TransverseCylindrical;
                     }
 
+                    Center = new Location(
+                        centralParallel != null ? centralParallel.Value : 0d,
+                        centralMeridian != null ? centralMeridian.Value : 0d);
+
                     scaleFactor = 1d;
                     bboxFormat = "{0},{1},{2},{3}";
                 }

MapProjections/Shared/PolarStereographicProjection.cs

@@ -19,7 +19,6 @@ namespace MapControl.Projections
         public static double ConvergenceTolerance { get; set; } = 1e-6;
         public static int MaxIterations { get; set; } = 10;
 
-        public bool IsNorth { get; }
         public double ScaleFactor { get; }
         public double FalseEasting { get; }
         public double FalseNorthing { get; }
@@ -27,7 +26,7 @@ namespace MapControl.Projections
         public PolarStereographicProjection(string crsId, bool isNorth, double scaleFactor, double falseEasting, double falseNorthing)
         {
             CrsId = crsId;
-            IsNorth = isNorth;
+            Center = new Location(isNorth ? 90d : -90d, 0d);
             ScaleFactor = scaleFactor;
             FalseEasting = falseEasting;
             FalseNorthing = falseNorthing;
@@ -35,7 +34,7 @@ namespace MapControl.Projections
 
         public override Vector GetRelativeScale(Location location)
         {
-            var lat = (IsNorth ? location.Latitude : -location.Latitude) * Math.PI / 180d;
+            var lat = Math.Sign(Center.Latitude) * location.Latitude * Math.PI / 180d;
             var a = Wgs84EquatorialRadius;
             var e = Wgs84Eccentricity;
             var s = Math.Sqrt(Math.Pow(1 + e, 1 + e) * Math.Pow(1 - e, 1 - e));
@@ -53,7 +52,7 @@ namespace MapControl.Projections
             var lat = location.Latitude * Math.PI / 180d;
             var lon = location.Longitude * Math.PI / 180d;
 
-            if (IsNorth)
+            if (Center.Latitude > 0d)
             {
                 lon = Math.PI - lon;
             }
@@ -92,7 +91,7 @@ namespace MapControl.Projections
                 lat = newLat;
             }
 
-            if (IsNorth)
+            if (Center.Latitude > 0d)
             {
                 lon = Math.PI - lon;
             }