topic Re: how to access esri from excel in ArcGIS API for Silverlight Questions

how to access esri from excel

ThaoNguyen — Tue, 22 Feb 2011 14:23:56 GMT

I created a map using C# and esri wpf.
We have an Excel add-in application that can open my map code. After my queryTask execute completed method is called, I invoked a method to add graphics to map. I got the following error when adding graphics to graphic layer: graphicMapLayer.Graphics.Add(graphic);

System.InvalidOperationException: The calling thread cannot access this object because a different thread owns it.
   at System.Windows.Threading.Dispatcher.VerifyAccess()

I found a solution by calling Dispatcher.Invoke
e.g. this.Dispatcher.Invoke( new AddGraphicDelegate(AddGraphic), graphic);

private void AddGraphic(Graphic g)
{
       graphicMapLayer.Graphics.Add(g);
}

However, after I got the above problem fixed, I got another thread exception for another arcgis method as following:

at System.Windows.Threading.Dispatcher.VerifyAccess()
   at System.Windows.DependencyObject.GetValue(DependencyProperty dp)
   at ESRI.ArcGIS.Client.Graphic.get_Visibility()
   at ESRI.ArcGIS.Client.GraphicsLayer.RenderGraphics(Double resolution, MapPoint canvasOrigin, Envelope env, Envelope bufferedExtent, IEnumerable`1 gfxs, Boolean isClustering, IRenderer renderer, Boolean interactive)
   at ESRI.ArcGIS.Client.GraphicsLayer.Draw(Envelope extent, Double resolution, MapPoint canvasOrigin, Boolean useTransitions)
   at ESRI.ArcGIS.Client.Map.loadLayerInView(Boolean useTransitions, Envelope drawExtent, Layer layer)
   at ESRI.ArcGIS.Client.Map.loadLayersInView(Boolean useTransitions, Envelope drawExtent)
   at ESRI.ArcGIS.Client.Map.panTo(Geometry geometry, Boolean skipAnimation)
   at ESRI.ArcGIS.Client.Map.zoomTo(Geometry geom, Boolean skipAnimation)
   at ESRI.ArcGIS.Client.Map.set_Extent(Envelope value)

Please help! I don't know where is the right place to call Invoke() in this case that handles all arcgis calls.

Thanks!

Re: how to access esri from excel

ThaoNguyen — Wed, 23 Feb 2011 13:48:28 GMT

I created a map using C# and esri wpf.
We have an Excel add-in application that can open my map code. After my queryTask execute completed method is called, I invoked a method to add graphics to map. I got the following error when adding graphics to graphic layer: graphicMapLayer.Graphics.Add(graphic);

System.InvalidOperationException: The calling thread cannot access this object because a different thread owns it.
   at System.Windows.Threading.Dispatcher.VerifyAccess()

I found a solution by calling Dispatcher.Invoke
e.g. this.Dispatcher.Invoke( new AddGraphicDelegate(AddGraphic), graphic);

private void AddGraphic(Graphic g)
{
       graphicMapLayer.Graphics.Add(g);
}

However, after I got the above problem fixed, I got another thread exception for another arcgis method as following:

at System.Windows.Threading.Dispatcher.VerifyAccess()
   at System.Windows.DependencyObject.GetValue(DependencyProperty dp)
   at ESRI.ArcGIS.Client.Graphic.get_Visibility()
   at ESRI.ArcGIS.Client.GraphicsLayer.RenderGraphics(Double resolution, MapPoint canvasOrigin, Envelope env, Envelope bufferedExtent, IEnumerable`1 gfxs, Boolean isClustering, IRenderer renderer, Boolean interactive)
   at ESRI.ArcGIS.Client.GraphicsLayer.Draw(Envelope extent, Double resolution, MapPoint canvasOrigin, Boolean useTransitions)
   at ESRI.ArcGIS.Client.Map.loadLayerInView(Boolean useTransitions, Envelope drawExtent, Layer layer)
   at ESRI.ArcGIS.Client.Map.loadLayersInView(Boolean useTransitions, Envelope drawExtent)
   at ESRI.ArcGIS.Client.Map.panTo(Geometry geometry, Boolean skipAnimation)
   at ESRI.ArcGIS.Client.Map.zoomTo(Geometry geom, Boolean skipAnimation)
   at ESRI.ArcGIS.Client.Map.set_Extent(Envelope value)

Please help! I don't know where is the right place to call Invoke() in this case that handles all arcgis calls.

Thanks!

Please help me as soon as possible because it is urgent for us :(. The map cannot be displayed and we cannot test it. Escalate the problem if you don't know an answer for this. I really appreciate your concern and understanding.

Re: how to access esri from excel

JenniferNery — Wed, 23 Feb 2011 16:04:18 GMT

I checked with Morten and he explained that you are using the wrong Dispatcher. You will need to get to the root visual, and use its Dispatcher. You can try using Application.Current.MainWindow.Dispatcher.

Re: how to access esri from excel

ThaoNguyen — Wed, 23 Feb 2011 16:35:02 GMT

I checked with Morten and he explained that you are using the wrong Dispatcher. You will need to get to the root visual, and use its Dispatcher. You can try using Application.Current.MainWindow.Dispatcher.

I tried this and the line Application.Current.MainWindow... threw the same exception.

Let me rewrite my original code structure

private void QueryTask_ExecuteCompleted(object sender, QueryEventArgs args)
{
    //do some work here that's not related to the question
    Update();
}

private delegate void NullDelegate();
private void Update()
{
            try
            {
                if (this.Dispatcher.Thread != System.Threading.Thread.CurrentThread)
                {
                    this.Dispatcher.Invoke(new NullDelegate(Update), null);
                    return;
                }

                //some work here

            }catch (Exception e) { //do something here }
}

With your suggestion, I did the following:

private void Update()
{
            try
            {
                if (Application.Current.MainWindow.Dispatcher.Thread != System.Threading.Thread.CurrentThread)
                {
                    Application.Current.MainWindow.Dispatcher.Invoke(new NullDelegate(Update), null);
                    return;
                }

                //some work here

            }catch (Exception e) { //do something here }
}

The if line already threw an exception.

Re: how to access esri from excel

JenniferNery — Sat, 11 Dec 2021 18:23:35 GMT

Does it hit this line?

Application.Current.MainWindow.Dispatcher.Invoke(new NullDelegate(Update), null);

I think the best way to find the parent of your Map control is to use VisualTreeHelper. If you do this in while loop until GetParent() returns null, you will have the Visual root and use its Dispatcher.
Something like this if Map is not a descendant of your Application.Current.MainWindow:

DependencyObject dependencyObject = VisualTreeHelper.GetParent(element);
if (dependencyObject == null)
 return element;
while (VisualTreeHelper.GetParent(dependencyObject) != null)   
 dependencyObject = VisualTreeHelper.GetParent(dependencyObject);
rootVisual = dependencyObject as Visual;

You will be able to then use rootVisual.Dispatcher.

Re: how to access esri from excel

ThaoNguyen — Sat, 11 Dec 2021 18:23:38 GMT

Does it hit this line?

I think the best way to find the parent of your Map control is to use VisualTreeHelper. If you do this in while loop until GetParent() returns null, you will have the Visual root and use its Dispatcher.
Something like this if Map is not a descendant of your Application.Current.MainWindow:
DependencyObject dependencyObject = VisualTreeHelper.GetParent(element);
if (dependencyObject == null)
 return element;
while (VisualTreeHelper.GetParent(dependencyObject) != null)   
 dependencyObject = VisualTreeHelper.GetParent(dependencyObject);
rootVisual = dependencyObject as Visual;
You will be able to then use rootVisual.Dispatcher.

Tried that, got same exception when doing VisualTreeHelper.GetParent(element).

Re: how to access esri from excel

ThaoNguyen — Fri, 25 Feb 2011 15:21:50 GMT

Tried that, got same exception when doing VisualTreeHelper.GetParent(element).

Do you have any other ideas after all of these solutions failed? You can tell me the big picture like where I should invoke the map container dispatcher or you can give me an example that worked on excel.
Thanks!

Re: how to access esri from excel

ThaoNguyen — Wed, 02 Mar 2011 14:11:35 GMT

Do you have any other ideas after all of these solutions failed? You can tell me the big picture like where I should invoke the map container dispatcher or you can give me an example that worked on excel.
Thanks!

We found that the Graphic instances created by Arcgis after QueryTask was completed in another thread. Temporarily, we have to create a new Graphic for each Graphic returned and pass in only info that we need. This resolved the problem.
I don't have to call dispatcher from mainwindow with this solution.