Crystal report (crystalReportsViewer) crash with null pointer exception

Question

Hi,
My application are simple : m_crystalReportsViewer.ViewerCore.ReportSource = report; but in throw exception null pointer when I call showDialog.
I see in code, we have method ShowTabHeader.
private void ShowTabHeader(bool isShow)
    Grid child = VisualTreeHelper.GetChild(this.tabViews, 0) as Grid;
    TabPanel panel = child.FindName("HeaderPanel") as TabPanel;
    if (!isShow)
        panel.Visibility = Visibility.Collapsed;
    else
        panel.Visibility = Visibility.Visible;
My problem :  child.FindName("HeaderPanel") as TabPanel return null
=>  if (!isShow)
        panel.Visibility = Visibility.Collapsed;
    else
        panel.Visibility = Visibility.Visible;
throws null pointer exception.
Do you have any idea about this?
Thanks.
Here is stack trace :
Unerwarteter Fehler im System ---> System.NullReferenceException: Object reference not set to an instance of an object.
   at SAPBusinessObjects.WPF.Viewer.ReportAlbum.ShowTabHeader(Boolean isShow)
   at SAPBusinessObjects.WPF.Viewer.ReportAlbum.ItemsChangedEventHandler(Object sender, ItemsChangedEventArgs e)
   at System.Windows.Controls.Primitives.ItemsChangedEventHandler.Invoke(Object sender, ItemsChangedEventArgs e)
   at System.Windows.Controls.ItemContainerGenerator.OnItemAdded(Object item, Int32 index)
   at System.Windows.Controls.ItemContainerGenerator.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Windows.Controls.ItemContainerGenerator.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
   at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
   at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
   at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Collections.Specialized.NotifyCollectionChangedEventHandler.Invoke(Object sender, NotifyCollectionChangedEventArgs e)
   at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Controls.ItemCollection.System.Windows.IWeakEventListener.ReceiveWeakEvent(Type managerType, Object sender, EventArgs e)
   at System.Windows.WeakEventManager.DeliverEventToList(Object sender, EventArgs args, ListenerList list)
   at System.Windows.WeakEventManager.DeliverEvent(Object sender, EventArgs args)
   at System.Collections.Specialized.CollectionChangedEventManager.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.CollectionView.OnCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.ListCollectionView.ProcessCollectionChangedWithAdjustedIndex(NotifyCollectionChangedEventArgs args, Int32 adjustedOldIndex, Int32 adjustedNewIndex)
   at System.Windows.Data.ListCollectionView.ProcessCollectionChanged(NotifyCollectionChangedEventArgs args)
   at System.Windows.Data.CollectionView.OnCollectionChanged(Object sender, NotifyCollectionChangedEventArgs args)
   at System.Collections.ObjectModel.ObservableCollection`1.OnCollectionChanged(NotifyCollectionChangedEventArgs e)
   at System.Collections.ObjectModel.ObservableCollection`1.InsertItem(Int32 index, T item)
   at System.Collections.ObjectModel.Collection`1.Add(T item)
   at SAPBusinessObjects.WPF.Viewer.ReportAlbum.OnCreateNewDocumentViewComplete(CreateNewDocumentArgs args)
   at SAPBusinessObjects.WPF.Viewer.DelegateMarshaler.<>c__DisplayClass6`1.<Invoke>b__4(Object )
   at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
   at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)
   --- End of inner exception stack trace ---
Edited by: duyhai707 on Jul 13, 2011 7:42 PM
Edited by: duyhai707 on Jul 13, 2011 8:09 PM

Answer 1

A lot I don't understand in here... actually, I don't understand anything in your post:
When you call ShowDialog, what exactly are you trying to show?  The code is the decompiled showtabheader method of the viewer. So, are you trying to override the viewer control and reportalbum?  My guess is that the null reference is for the reportalbum's child object which is not the reportalbum object of the viewer.  I don't understand why the code since its all handled internally to the viewer anyhow.
Perhaps searching the forum for code sample will help?
Also, see the [WPF Demo|http://www.sdn.sap.com/irj/scn/elearn?rid=/library/uuid/a09f7025-0629-2d10-d7ae-df006a51d1a8]
Other good WPF resources to consult:
http://www.redmondpie.com/incorporate-crystal-reports-in-a-c-wpf-application/
http://www.sdn.sap.com/irj/scn/elearn?rid=/library/uuid/a09f7025-0629-2d10-d7ae-df006a51d1a8
http://www.codeproject.com/Tips/74499/Crystal-Report-in-WPF.aspx
Re: Crystal Reports for Visual Studio 2010 - WPF Viewer for .Net 4.0
http://codegain.com/articles/crystalreports/howto/incorporate-crystal-reports-in-wpf-using-c-sharp.aspx
CRVS2010 Beta - WPF Viewer, how to hide the GroupTree control?
Re: CRVS2010 Beta - WPF Viewer, how to hide the GroupTree control?
Ludek
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