From c17092cd38c94f9f9a7242798e19d4ead3c047ac Mon Sep 17 00:00:00 2001
From: Clemens <fischer.clemens@gmail.com>
Date: Thu, 11 Nov 2021 22:27:57 +0100
Subject: [PATCH] Add IsBaseMapLayer property

---
 MapControl/Shared/MapTileLayer.cs               | 2 +-
 MapControl/Shared/MapTileLayerBase.cs           | 9 +++++++--
 MapControl/Shared/WmtsTileLayer.cs              | 6 +++---
 SampleApps/ProjectionDemo/ProjectionDemo.csproj | 2 +-
 4 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/MapControl/Shared/MapTileLayer.cs b/MapControl/Shared/MapTileLayer.cs
index 4b77e5ad..9849df10 100644
--- a/MapControl/Shared/MapTileLayer.cs
+++ b/MapControl/Shared/MapTileLayer.cs
@@ -211,7 +211,7 @@ namespace MapControl
             }
             else
             {
-                var minZoomLevel = LoadBackgroundTiles
+                var minZoomLevel = IsBaseMapLayer
                     ? Math.Max(TileMatrix.ZoomLevel - MaxBackgroundLevels, MinZoomLevel)
                     : maxZoomLevel;
 
diff --git a/MapControl/Shared/MapTileLayerBase.cs b/MapControl/Shared/MapTileLayerBase.cs
index cf3f96a1..0ec2c284 100644
--- a/MapControl/Shared/MapTileLayerBase.cs
+++ b/MapControl/Shared/MapTileLayerBase.cs
@@ -176,9 +176,14 @@ namespace MapControl
             }
         }
 
-        protected bool LoadBackgroundTiles
+        protected bool IsBaseMapLayer
         {
-            get { return this == parentMap?.MapLayer; }
+            get
+            {
+                return parentMap != null
+                    && parentMap.Children.Count > 0
+                    && parentMap.Children[0] == this;
+            }
         }
 
         private async void OnViewportChanged(object sender, ViewportChangedEventArgs e)
diff --git a/MapControl/Shared/WmtsTileLayer.cs b/MapControl/Shared/WmtsTileLayer.cs
index b5718fad..d10520ff 100644
--- a/MapControl/Shared/WmtsTileLayer.cs
+++ b/MapControl/Shared/WmtsTileLayer.cs
@@ -120,15 +120,15 @@ namespace MapControl
             var layersChanged = false;
             var maxScale = 1.001 * ParentMap.ViewTransform.Scale; // avoid rounding issues
 
-            // show all TileMatrix layers with Scale <= maxScale, at least the first layer
+            // show all WmtsTileMatrix layers with Scale <= maxScale, at least the first layer
             //
             var currentMatrixes = tileMatrixSet.TileMatrixes
                 .Where((matrix, i) => i == 0 || matrix.Scale <= maxScale)
                 .ToList();
 
-            if (!LoadBackgroundTiles)
+            if (!IsBaseMapLayer) // show only the last layer
             {
-                currentMatrixes = currentMatrixes.Skip(currentMatrixes.Count - 1).ToList(); // last element only
+                currentMatrixes = currentMatrixes.Skip(currentMatrixes.Count - 1).ToList();
             }
             else if (currentMatrixes.Count > MaxBackgroundLevels + 1)
             {
diff --git a/SampleApps/ProjectionDemo/ProjectionDemo.csproj b/SampleApps/ProjectionDemo/ProjectionDemo.csproj
index b501a207..2472a479 100644
--- a/SampleApps/ProjectionDemo/ProjectionDemo.csproj
+++ b/SampleApps/ProjectionDemo/ProjectionDemo.csproj
@@ -2,7 +2,7 @@
 
     <PropertyGroup>
         <OutputType>WinExe</OutputType>
-        <TargetFramework>net5.0-windows</TargetFramework>
+        <TargetFramework>net6.0-windows</TargetFramework>
         <UseWPF>true</UseWPF>
         <Version>6.1.0</Version>
         <Authors>Clemens Fischer</Authors>