How can I add additional item templates to an extended WPF treeview

I'm trying to set up a Treeview descendent class that can be used as a common template for all Treeview instances in my application, but with additional formatting and templates for each instance.

For the base, I have a UserControl that descends from Treeview, with the common styles and a single standard data template

<TreeView x:Class="BaseTreeView" ... >
    <TreeView.ItemContainerStyle> ... </TreeView.ItemContainerStyle>
    <TreeView.Resources>
        <HierarchicalDataTemplate ItemsSource="{Binding Children}"  DataType="{x:Type local:BaseTreeViewItem}">
            <TextBlock Text="{Binding Caption}" />
        </HierarchicalDataTemplate>
    </TreeView.Resources>
</TreeView>

Then in each window, I use this extended Treeview and add additional data templates for the specific TreeviewItems I'm displaying.

e.g.

<Window x:Class="Window1" ... >
    ...
    <BaseTreeView ItemsSource="{Binding RootTreeItems}" >
        <MyTreeView.Resources>
            <HierarchicalDataTemplate ItemsSource="{Binding Children}"  DataType="{x:Type ExtendedTreeViewItem1}">
                <StackPanel Orientation="Horizo开发者_如何学JAVAntal">
                    <Image Source="Images/Image1.png" />
                    <TextBlock Text="{Binding Caption}" />
                </StackPanel>
            </HierarchicalDataTemplate>
            <DataTemplate DataType="{x:Type ExtendedTreeViewItem2}">
                <StackPanel Orientation="Horizontal">
                    <Image Source="Images/Image2.png" />
                    <TextBlock Text="{Binding Caption}" />
                </StackPanel>
            </DataTemplate>
        </MyTreeView.Resources>
    </BaseTreeView>
    ...
</Window>

This compiles fine, but at runtime I get an error

"'Set property 'System.Windows.ResourceDictionary.DeferrableContent' threw an exception.' Line number '27' and line position '59'."

"Cannot re-initialize ResourceDictionary instance."

Is there any way around this, or can someone suggest a better way to set up a base treeview template and multiple descedent versions.

You could try moving your templates to the <Window.Resources> instead of <MyTreeView.Resources>

If it doesn't work, maybe using a DataTemplateSelector suits your case best. You can create a DataTemplateSelector class like this:

public class ExtendedTreeViewTemplateSelector : DataTemplateSelector
{
    public DataTemplate ExtendedTreeViewItem1Template { get; set; }
    public DataTemplate ExtendedTreeViewItem2Template { get; set; }


    public override DataTemplate SelectTemplate(object item, DependencyObject container)
    {
        if (item is ExtendedTreeViewItem1)
            return ExtendedTreeViewItem1Template;
        if (item is ExtendedTreeViewItem2)
            return ExtendedTreeViewItem2Template;
    }
}

And then use it in your XAML like this:

<Window x:Class="Window1" ... >
    <Window.Resources>
        <HierarchicalDataTemplate x:Key="extendedTreeViewItem1Template" ItemsSource="{Binding Children}"  DataType="{x:Type ExtendedTreeViewItem1}">
            <StackPanel Orientation="Horizontal">
                <Image Source="Images/Image1.png" />
                <TextBlock Text="{Binding Caption}" />
            </StackPanel>
        </HierarchicalDataTemplate>
        <DataTemplate x:Key="extendedTreeViewItem2Template" DataType="{x:Type ExtendedTreeViewItem2}">
            <StackPanel Orientation="Horizontal">
                <Image Source="Images/Image2.png" />
                <TextBlock Text="{Binding Caption}" />
            </StackPanel>
        </DataTemplate>
        <selector:ExtendedTreeViewTemplateSelector x:Key="treeViewTemplateSelector"
                                                   ExtendedTreeViewItem1Template="{StaticResource extendedTreeViewItem1Template}"
                                                   ExtendedTreeViewItem2Template="{StaticResource extendedTreeViewItem2Template}" />
    </Window.Resources>
    ...
    <BaseTreeView ItemsSource="{Binding RootTreeItems}"
                  ItemTemplateSelector={StaticResource treeViewTemplateSelector}" />
    ...
</Window>