WPF Custom Control Default Databinding

Question

I'm just now entering the realm of WPF, and I would like to create a custom control. I'm not too concerned about the styling of it, but rather the functionality.

I'm trying to create a custom Tree View that auto-magically fills up with data from a different library so that other WPF applications are able to use this control, and expose this data to their users, and get feedback with ease.

IE:

+-----------------------------+
|+Project                     |
|+-- File                     |
|+---- Patch                  |
|+Other Project               |
|+-- Files Are Nifty          |
|+---- Yup.                   |
+-----------------------------+

I want ^that^ to be a re-useable control that should always have the same data among all of its instances. Essentially, a default data-binding. I've done a bit of googling, and I searched in here but all of the questions / answers either weren't relevant, were over my head, or both. The only bit of useful information I found was that in the data-provider to have two branches, return a CompositeCollection.

If somebody could explain this, step-by-step for a WPF Custom Control library, I would much appreciate it.

Answer 1

If your data is always in the same pattern (eg Projects have Files, which have Patches), you dont necessarily need a CompositeCollection. You could also use HierarchicalDataTemplates to display your data like so:

    <HierarchicalDataTemplate x:Key="ProjectTemplate"
ItemsSource="{Binding ChildCollection}"
ItemTemplate="{StaticResource FileTemplate}">
        <here comes the actual TreeViewItem of this Template>
    </HierarchicalDataTemplate>

Your FileTemplate is another HierarchicalDataTemplate, this goes on until you reached the lowest level, this will be a DataTemplate. All these templates are placed in the resources, now all you have to to is setting the TreeView's ItemTemplate to the top level HierarchicalDataTemplate (ProjectTemplate):

                    <TreeView ItemsSource="{Binding Path=ChildCollection, UpdateSourceTrigger=PropertyChanged}" ItemTemplate="{StaticResource ResourceKey=ProjectTemplate}">
                    </TreeView>

Your Data could look like the following:

public class Project
{
     public ObservableCollection<File> ChildCollection {get;set;}
}

A File has another ChildCollection (eg ObservableCollection<Patch> ) aso
To set a default DataContext, you could set the DataContext in the constructor to a ViewModel which has a ChildCollection of Type ObservableCollection<Project> .