From db7ed3cb11f3eed020d7eba8d1ba18f3d9494164 Mon Sep 17 00:00:00 2001
From: David Moor <dave@ducks-n-tworms.co.uk>
Date: Wed, 15 Jul 2026 08:43:59 +0100
Subject: [PATCH] Implement initial map reference system in BaseMapLayer

Added initial map reference system handling for tile source changes.
---
 EGIS.Controls/BaseMapLayer.cs | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/EGIS.Controls/BaseMapLayer.cs b/EGIS.Controls/BaseMapLayer.cs
index c95564b..d938834 100644
--- a/EGIS.Controls/BaseMapLayer.cs
+++ b/EGIS.Controls/BaseMapLayer.cs
@@ -32,6 +32,7 @@
 using System.Linq;
 using System.Text;
 using System.Threading.Tasks;
+using EGIS.Projections;
 
 
 namespace EGIS.Controls
@@ -105,6 +106,7 @@ private void Map_ZoomLevelChanged(object sender, EventArgs e)
         }
 
 		private TileSource _tileSource;
+		private ICRS _initialMapReferenceSystem;
 		private bool disposedValue;
 
 		/// <summary>
@@ -124,9 +126,14 @@ public TileSource TileSource
 					_tileSource = value;
 					if (previousTileSource == null)
 					{
+						_initialMapReferenceSystem = mapReference.MapCoordinateReferenceSystem;
 						//if TileSource changed from null set the maps CRS to Wgs84PseudoMercator
 						mapReference.MapCoordinateReferenceSystem = EGIS.Projections.CoordinateReferenceSystemFactory.Default.GetCRSById(EGIS.Projections.CoordinateReferenceSystemFactory.Wgs84PseudoMercatorEpsgCode);
 					}
+					else if (_tileSource == null)
+					{
+						mapReference.MapCoordinateReferenceSystem = _initialMapReferenceSystem;
+					}
 					mapReference.Invalidate(RefreshMode.BaseMapLayer);
 				}
 			}