Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-03-2008 8:46 AM |

Hi all!

I have created a custom contentcontrol which basicly is a button.
When I add this button to the xaml it all works fine:  

<UserControl x:Class="MyControls.MyButtonParent"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" 
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" 
    xmlns:custom="clr-namespace:MyControls;assembly=MyControls" 
    Width="Auto" Height="Auto">
    <Grid x:Name="LayoutRoot" Background="White">
        <StackPanel x:Name="stackpanelAll" Width="Auto" Height="Auto" HorizontalAlignment="Left">
            <custom:MyButton Content="Hello world"></custom:MyButton>
        </StackPanel>
    </Grid>
</UserControl>

Now I want to do the same in the code behind:

1    MyButton button = new MyButton()
2    {
3      Height = 30,
4      Width = Double.NaN,
5      Content = "Hello2"
6    }
7    
8    LayoutRoot.Children.Add(button);

This works fine as well.

But now I want to do something differtent:

I have created a UserControl which has a Grid and inside this grid a StackPanel. 
The StackPanels height is set to Auto. I add this UserControl to the Page.Xaml.
Then in the code behind of the Page I try to create the button again and add it 
to the StackPanel of my UserControl. 
To do this I have added a method in my UserControl which basicly does nothing else than: 

1    private void AddElement(FrameworkElement element)
2    {
3      stackPanelContent.Children.Add(element);
4    }

But now the button will NOT show! When I debug in de AddElement method I 
can see that the ActualHeight of the button is 0.0.  
I have tried to force the layout of the button by using button.UpdateLayout() 
but still no luck.

Can anybody tell me how to create this control and be able to (pre)render it 
so that I can get it's (actual)height?

Thanks!

Regards,
Marrik

Ps: This is done in Silverlight 2 RC0.

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-03-2008 11:34 AM |

Hi! Thanks for your reply.

The problem is that in the code behind I do some calculations on the FrameworkElement that is added to the stackpanel.
At runtime the actualsize on adding is always 0.0. I am not able to test your code now but I am sure that the same will happen.

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-03-2008 11:53 AM |

 Hi,

In my code also initial Height is Zero as i have not Specified that.

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-03-2008 12:00 PM |

I have specified it (30) but it still appears as 0.0. Only after a "postback" (so to say) the value of the height is set to 30.

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-06-2008 5:11 AM |

Hi,

After Rendering it take some time.

Before that it will show you 0 only.

You can use dispatcher timer here and Put a delay and after that you can check that..

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-06-2008 5:19 AM |

This can't be done either: I am adding some (own built) ContentControls to my usercontrol at runtime (right after the page load event).

So a delay at any point won't do any good since the moment I add the contentcontrols I do some calculations (for example: calculate the total needed height for my usercontrol). And this is done immediatly.

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-07-2008 1:16 AM |

Hello, can you post more code? After you call button.UpdateLayout, the ActualWidth/Height should be ready...

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-07-2008 12:34 PM |

Yes, I will try to post a complete sample application which has this behaviour later this evening.

But I am doing a button.UpdateLayout() and still both the Height and ActualHeight are 0.0. :(

Re: Creating a custom contentcontrol at runtime gives an ActualHeight of 0.0

10-12-2008 7:52 AM |

Closing this question. I solved it by instead of creating a contentcontrol creating a usercontrol that derives from a StackPanel.
Inside this usercontrol I can do the things needed in the Page_Loaded event.

Thanks all.