Wpf Core: Error message when adding an overlay on the map

[Stephanie_COURRILLAU]

Hi,

We are migrating Thinkgeo to a WPF core version.
When I run our application, in the loaded event, I get an “Object reference not set to an instance of an object” error.
However this error appears randomly, sometimes the application starts, everything works well and other times the error message appears.
The error appears when adding an overlay on the map (_wpfMap.Overlays.Add (overlay))

Have you ever encountered this problem ?

Thank you.
Regards.

Steph.

Error message :

at ThinkGeo.Core.MapViewBase.gEQ=(Object sender, AddedGeoCollectionEventArgs e)
at ThinkGeo.Core.GeoCollection1.OnAdded(AddedGeoCollectionEventArgs e) at ThinkGeo.Core.GeoCollection1.Add(String key, T item)
at ThinkGeo.Core.GeoCollection1.Add(T item) at Workspaces.Cartographie.Layers.LayerService.CréerOverlayRaster(IEnumerable1 couches, IEnumerable`1 coucheCartoIds, Boolean isBaseMap) in C:\StephTFSCore\Workspaces.Cartographie\Layers\LayerService.cs:line 204

• $exception {“Object reference not set to an instance of an object.”} System.NullReferenceException
• Data {System.Collections.ListDictionaryInternal} System.Collections.IDictionary {System.Collections.ListDictionaryInternal}
  HResult -2147467261 int
  HelpLink null string
• InnerException null System.Exception
  Message “Object reference not set to an instance of an object.” string
  Source “ThinkGeo.UI.Wpf” string
  StackTrace " at ThinkGeo.Core.MapViewBase.gEQ=(Object sender, AddedGeoCollectionEventArgs e)\r\n at ThinkGeo.Core.GeoCollection1.OnAdded(AddedGeoCollectionEventArgs e)\r\n at ThinkGeo.Core.GeoCollection1.Add(String key, T item)\r\n at ThinkGeo.Core.GeoCollection1.Add(T item)\r\n at Workspaces.Cartographie.Layers.LayerService.CréerOverlayRaster(IEnumerable1 couches, IEnumerable`1 coucheCartoIds, Boolean isBaseMap) in C:\StephTFSCore\Workspaces.Cartographie\Layers\LayerService.cs:line 204" string
• TargetSite {Void gEQ=(System.Object, ThinkGeo.Core.AddedGeoCollectionEventArgs)} System.Reflection.MethodBase {System.Reflection.RuntimeMethodInfo}
  Attributes Private | HideBySig System.Reflection.MethodAttributes
  CallingConvention Standard | HasThis System.Reflection.CallingConventions
  ContainsGenericParameters false bool
  CustomAttributes La méthode System.Reflection.MemberInfo.get_CustomAttributes ne peut pas être appelée dans ce contexte. System.Collections.Generic.IEnumerable<System.Reflection.CustomAttributeData>
• DeclaringType {Name = “MapViewBase” FullName = “ThinkGeo.Core.MapViewBase”} System.Type {System.RuntimeType}
  IsAbstract false bool
  IsAssembly false bool
  IsCollectible La méthode System.Reflection.RuntimeMethodInfo.get_IsCollectible ne peut pas être appelée dans ce contexte. bool
  IsConstructedGenericMethod La méthode System.Reflection.MethodBase.get_IsConstructedGenericMethod ne peut pas être appelée dans ce contexte. bool
  IsConstructor false bool
  IsFamily false bool
  IsFamilyAndAssembly false bool
  IsFamilyOrAssembly false bool
  IsFinal false bool
  IsGenericMethod false bool
  IsGenericMethodDefinition false bool
  IsHideBySig true bool
  IsPrivate true bool
  IsPublic false bool
  IsSecurityCritical La méthode System.Reflection.RuntimeMethodInfo.get_IsSecurityCritical ne peut pas être appelée dans ce contexte. bool
  IsSecuritySafeCritical La méthode System.Reflection.RuntimeMethodInfo.get_IsSecuritySafeCritical ne peut pas être appelée dans ce contexte. bool
  IsSecurityTransparent La méthode System.Reflection.RuntimeMethodInfo.get_IsSecurityTransparent ne peut pas être appelée dans ce contexte. bool
  IsSpecialName false bool
  IsStatic false bool
  IsVirtual false bool
  MemberType Method System.Reflection.MemberTypes
  MetadataToken 100663828 int
• MethodHandle {System.RuntimeMethodHandle} System.RuntimeMethodHandle
  MethodImplementationFlags La méthode System.Reflection.MethodBase.get_MethodImplementationFlags ne peut pas être appelée dans ce contexte. System.Reflection.MethodImplAttributes
• Module {ThinkGeo.UI.Wpf.dll} System.Reflection.Module {System.Reflection.RuntimeModule}
  Name “gEQ=” string
• ReflectedType ‘((System.Reflection.RuntimeMethodInfo)($exception).TargetSite).ReflectedType’ threw an exception of type ‘System.NotSupportedException’ System.Type {System.NotSupportedException}
• ReturnParameter {System.Void } System.Reflection.ParameterInfo
• ReturnType {Name = “Void” FullName = “System.Void”} System.Type {System.RuntimeType}
  ReturnTypeCustomAttributes La méthode System.Reflection.RuntimeMethodInfo.get_ReturnTypeCustomAttributes ne peut pas être appelée dans ce contexte. System.Reflection.ICustomAttributeProvider

[Frank4]

Thanks Stephanie,
We did saw this issue before. If the map component not put into the wpf container. This may happen. More detail you can check here.

V12.1 - Map object initialization

Thanks Peter, As talked with the development team. Looking into more detail. For the mapview object we have to add it to some WPF control. Basically this is the same as you mentioned. FirstMap = new MapView(); mainGrid.Children.Add(FirstMap); FirstMap.Loaded += FirstMap_Loaded; private void FirstMap_Loaded(object sender, RoutedEventArgs e) { FirstMap.MapUnit = GeographyUnit.Meter; FirstMap.CurrentExtent = new RectangleShape(-10000000, 10000000, …

If this is not your case. Could you create a simple sample to reproduce this issue. We could look into more detail.

Thanks

Frank

[Stephanie_COURRILLAU]

Hi Franck,

Thanks for your answer.

Compared to the solution provided in this post, does this mean that in core, we have to add the map to a grid, in code behind ?
Currently in our application, we are adding the map to the grid in xaml (ie below).

    <Grid x:Name="GridPrincipaleWorskpace">
            <Grid.RowDefinitions>         
                < RowDefinition Height="Auto" />
                < RowDefinition Height="Auto" />
                < RowDefinition Height="*" x:Name="RowLayer" />
                < RowDefinition Height="Auto" />
            </Grid.RowDefinitions>

            <wpf:MapView x:Name="Map"
                        Background="White"
                        Grid.Row="0"
                        Grid.RowSpan="4" />
.....
            </wpfMapView>
    </Grid>

.

With core, do we have to add the map to the grid in code behind ?

Thanks.
Regards.
Steph.

[Frank4]

Thanks Steph,
No. You don’t have to add the map to the gird in code behind. What you are doing is correct with xaml . The point in the post is we can not just initialize the map by the simple two lines.

var FirstMap = new MapView();
FirstMap.Overlays?.Add(new LayerOverlay()); // Crash here

More detail is here

V12 NullReferenceException when adding to MapView

Hello, I have some code that seemed to work prior to the upgrade to V12 involving MapView. I am attempting to add an Overlay like this: FirstMap = new MapView(); FirstMap.Overlays?.Add(new LayerOverlay()); // Crash here I am getting a NullReferenceException everytime I try to .add to this list, I crash out with this exception: [crash] Is there something else I need to do now before adding to the Overlays list? Thanks, Matt

Sorry for the confuse. Back to your original issue. Could you send us the LayerService.cs file to us. We could look into more detail.

Thanks

Frank