topic Re: Map.MouseMove Event issues in ArcGIS API for Silverlight Questions

Map.MouseMove Event issues

jonataspovoas — Sat, 11 Dec 2021 11:49:06 GMT

Hi,

I'm making a funcion to show the mouse position on the map, but I'm having trouble fixing the following problem.

If the user moves the mouse through the application before it finishes loading, this error occurs:

Runtime Error in Microsoft JScript: Unhandled Error in Silverlight Application Object reference not set to an instance of an object. 
   in MDSalvador.MainPage.Mapa_MouseMove (Object sender, MouseEventArgs e)
   in MS.Internal.CoreInvokeHandler.InvokeEventHandler (Int32 typeIndex, handlerDelegate Delegate, Object sender, Object args)
   in MS.Internal.JoltHelper.FireEvent (unmanagedObj IntPtr, IntPtr unmanagedObjArgs, argsTypeIndex Int32, String eventName)

I'm basicaly using the function shown here : http://help.arcgis.com/en/webapi/silverlight/samples/start.htm#MouseCoords except for that i'm showing only the coordinates of the map.

Re: Map.MouseMove Event issues

JenniferNery — Tue, 21 Sep 2010 15:54:02 GMT

I'm not able to replicate the issue using the SDK sample. What might be causing delay loading the map? I tried moving the mouse while the map is still loading and I do not get object reference not set to an instance exception. Have you tried setting breakpoint in the MouseMove event handler?

Re: Map.MouseMove Event issues

AliMirzabeigi — Sat, 11 Dec 2021 11:49:09 GMT

Add the following on your page constructor. MyMap is your map control:

MyMap.Layers.LayersInitialized += new ESRI.ArcGIS.Client.LayerCollection.LayersInitializedHandler(Layers_LayersInitialized);

The LayersInitialized event handler will hook up the mouse move handler of your map control:

private void Layers_LayersInitialized(object sender, EventArgs args)
{
   MyMap.MouseMove += new MouseEventHandler(MyMap_MouseMove);
}

Re: Map.MouseMove Event issues

jonataspovoas — Sat, 11 Dec 2021 11:49:12 GMT

Add the following on your page constructor. MyMap is your map control:
MyMap.Layers.LayersInitialized += new ESRI.ArcGIS.Client.LayerCollection.LayersInitializedHandler(Layers_LayersInitialized);
The LayersInitialized event handler will hook up the mouse move handler of your map control:
private void Layers_LayersInitialized(object sender, EventArgs args)
{
   MyMap.MouseMove += new MouseEventHandler(MyMap_MouseMove);
}

Thanks a lot, this solved the problem 🙂

Re: Map.MouseMove Event issues

AliMirzabeigi — Wed, 22 Sep 2010 14:17:45 GMT

Great! Just a quick comment that you should also make sure that you are not hooking up the map's MouseMove event handler more than once. This could be the case where you have a GraphicsLayer that could be initialized later in your application.