Question

I have a ComboBox whose ItemsSource is bound to an ObjectDataProvider that has its IsAsynchronous property set to true. Inside the method that loads the data , I put a Wait for 10 seconds, to simulate a long loading time for this data.

The Asynchronous loading works great – the entire window is still responsive, and after 10 seconds I see the ComboBox dropdown populated.

I would like to alert the user that this specific ComboBox is loading data, during that 10 second wait time. Something like a progressBar in the background of the control, that is enabled only while a certain ‘isLoading’ property or whatever is set to true. Is it possible to accomplish this?

Thanks.

Answer 1

this looks like the Priority Binding could be a solution for you

<ListBox>
    <ListBox.ItemsSource>
    <PriorityBinding>
        <!-- highest priority sources are first in the list -->
        <Binding Path="LongLoadingCollection" IsAsync="True" />
        <!-- this contains only one item like "loading data..." -->
        <Binding Path="LoadMessage" IsAsync="True" />
    </PriorityBinding>
    </ListBox.ItemsSource>
</ListBox>

here is an good tutorial for Priority Bindings
http://www.switchonthecode.com/tutorials/wpf-tutorial-priority-bindings

or take a look at msdn
http://msdn.microsoft.com/en-us/library/system.windows.data.prioritybinding.aspx

hope this helps