Question

I’m trying to understand the HelloScreens sample that comes with Caliburn.Micro. The ShellView.xaml includes a ContentControl at the bottom. Can someone please explain the importance of this element? I have tried to comment it out without seeing any difference.

<UserControl x:Class="Caliburn.Micro.HelloScreens.Shell.ShellView"
             xmlns:...>
    <Grid>
    <local:TiledBackground SourceUri="/Resources/Images/backgroundtexture.png" />
        <Image Source="/Resources/Images/backgroundshadow.png"
               Stretch="Fill" />

        <ct:DockPanel>
          <.../>
        </ct:DockPanel>

        <!--  Whats this one for?  --/>
        <ContentControl x:Name="Dialogs" 
                        VerticalContentAlignment="Stretch"
                        HorizontalContentAlignment="Stretch"/>
    </Grid>

</UserControl>

It’s binded to the viewmodels Dialogs-property, which is an custom implementation of IConductActiveItem, but what is it used for?

Answer 1

Whenever you have a ContentControl with the same name as a view model property, Caliburn.Micro will find the corresponding view for that view model, inject the view into the ContentControl, and bind up the view model to the view.

In this case, the Dialogs property is an IDialogManager type as you say, which resolves to DialogConductorViewModel (a conductor type). So the DialogConductorView is injected into the content control.

This view displays the dialogs in the application, and if you look at the view, it also has a ContentControl which displays the current ActiveItem. This is typical of a Caliburn.Micro conductor.

<Controls:CustomTransitionControl x:Name="ActiveItem" Margin="8" />

Note that the DialogConductorView is always displayed over the content of the application in ShellView, but the Grid inside the DialogConductorView is only visible if the ActiveItem is not null.

<Grid Visibility="{Binding ActiveItem, Mode=TwoWay, 
Converter={StaticResource nullToCollapsed}}"