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[Solved] Delay in instantiating objects?

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Docking

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C Bates asked on 19 Jan 2010, 05:52 PM

Hello,

We are trying to use the MVVM pattern with our application. We have a custom control based on a template. We create RadTabItems programmatically and add our custom control to Canvas contained by the RadTabItem.

The first time a RadTabItem is created, and a control added, there seems to be a delay in the custom control's OnApplyTemplate() being called (suggesting that the control isn't getting added to the visual tree). When a ViewModel object is updated, and the corresponding View object tries to update itself, not all the parts are instantiated.

I have a test app, w/o the MVVM and events and handlers, that I think demonstrates this.

The xaml:

                    <dock:RadDocking x:Name="Docking" Grid.Column="0" Grid.Row="1" >         
                 <dock:RadDocking.DocumentHost>         
                    <dock:RadSplitContainer x:Name="splitContainer1">         
                        <dock:RadPaneGroup x:Name="leftMapGroup" >         
                            <dock:RadPane x:Name="_leftPane" CanDockInDocumentHost="False" CanFloat="False" CanUserClose="False"         
            CanUserPin="False" >         
                                <nav:RadTabControl x:Name="_leftTabCntrl" AllowDragReorder="True">         
                                </nav:RadTabControl>         
                            </dock:RadPane>         
                        </dock:RadPaneGroup>         
                    </dock:RadSplitContainer>         
                </dock:RadDocking.DocumentHost>         
            </dock:RadDocking>         
                                 
            <Canvas Grid.Column="1" x:Name="rightCanvas"> </Canvas>         

Code to add a custom control:

                    private void addNode_Click(object sender, RoutedEventArgs e)         
            {         
                // Add a node to both the docking container and the plain canvas         
                if (_leftTabCntrl.Items.Count < 1) {         
                    RadTabItem ti = new RadTabItem() { Content = new Canvas()          
                       };         
                    _leftTabCntrl.Items.Add(ti);         
                }         
                Thing nod = new Thing(cntr++ );         
                RadTabItem tii = _leftTabCntrl.Items[0] as RadTabItem;         
                if (null != tii) {         
                    Canvas cvs = tii.Content as Canvas;         
                    if (null != cvs) {         
                        cvs.Children.Add(nod);         
                    }         
                }         
                nod.ApplyTemplate(); // This does not execute; can't step in, breakpoint not hit        
                     
                Thing nod2 = new Thing(cntr++ );         
                rightCanvas.Children.Add(nod2);         
                nod2.ApplyTemplate();   // This DOES execute, can step in        
            }         
                     

To reiterate, it is possible in our application for the ViewModel object to try to update the View object before the View object (the Thing control) is fully instantiated.

Any suggestions would be appreciated....

[Solved] Delay in instantiating objects?

2 Answers, 1 is accepted