How to "Navigate" with a Prism Custom adapter? - wpf

Question

I've a Prism Custom Region Adapter, to display every view in a different tab of our DevExpress "DocumentGroup".
In order to do this, I've the following RegionAdapter:
public class DocumentGroupRegionAdapter : RegionAdapterBase<DocumentGroup>
{
public DocumentGroupRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory)
: base(regionBehaviorFactory)
{
}
protected override void Adapt(IRegion region, DocumentGroup regionTarget)
{
region.Views.CollectionChanged += (sender, args) =>
{
if (args.Action == NotifyCollectionChangedAction.Add)
{
foreach (FrameworkElement element in args.NewItems)
{
DocumentPanel documentPanel = new DocumentPanel {Content = element, DataContext = element.DataContext};
regionTarget.Items.Add(documentPanel);
}
}
};
}
protected override IRegion CreateRegion()
{
return new AllActiveRegion();
}
}
With AllActiveRegion being:
public class AllActiveRegion : Region
{
public override IViewsCollection ActiveViews
{
get { return Views; }
}
public override void Deactivate(object view)
{
throw new InvalidOperationException(Resources.DeactiveNotPossibleException);
}
}
And we were registering several View for this region:
_regionManager.RegisterViewWithRegion(Regions.MainSections, typeof(Views.Layout.RootView));
_regionManager.RegisterViewWithRegion(Regions.MainSections, typeof(Views.Configure.RootView));
_regionManager.RegisterViewWithRegion(Regions.MainSections, typeof(Views.Dashboard.RootView));
It worked fine up until now, but now, on certain options, we need to activate one of the tab. This would be done by calling item.IsActive = true.
How do I specify which item I want to navigate too?
What should I override to set this active item?

Answer 1

For the interested ones, I had to do several things to resolve the issue:
Switch to the SingleActiveRegion instead of the AllActiveRegion. The AllActiveRegion doesn't keep track of the selected(active) item, basically, the region.Views = region.ActiveViews. So you cannot register to ActiveViews changes.
Listen to the region.ActiveViews.CollectionChanged event. When it fires, I've to activate the DevExpress component
Listen to the DevExpress component for when the user clicks on the tabs. This is required, because otherwise Prism might think the control is already active and not active it again.
The code look like this:
public class DocumentGroupRegionAdapter : RegionAdapterBase<DocumentGroup>
{
public DocumentGroupRegionAdapter(IRegionBehaviorFactory regionBehaviorFactory)
: base(regionBehaviorFactory)
{
}
protected override void Adapt(IRegion region, DocumentGroup regionTarget)
{
region.Views.CollectionChanged += (_, args) =>
{
if (args.Action == NotifyCollectionChangedAction.Add)
{
foreach (FrameworkElement element in args.NewItems)
{
DocumentPanel documentPanel = new() {Content = element, DataContext = element.DataContext};
regionTarget.Items.Add(documentPanel);
}
}
};
region.ActiveViews.CollectionChanged += (_, args) =>
{
if (args.Action == NotifyCollectionChangedAction.Add)
{
foreach (FrameworkElement element in args.NewItems)
{
DocumentPanel existingItem = regionTarget.Items.Cast<DocumentPanel>().FirstOrDefault(i => i.Content == element);
if (existingItem != null)
{
existingItem.IsActive = true;
}
}
}
};
regionTarget.SelectedItemChanged += ((_, args) =>
{
region.Activate(((DocumentPanel)args.Item).Content);
});
}
protected override IRegion CreateRegion()
{
return new SingleActiveRegion();
}
}
Now that I've seen the source code of Prism, I think writing a custom Region could maybe also do the job, I'm not totally sure when the Activate() is called