findResource()不使用数据模板

<s:SurfaceWindow.Resources>
    <ImageBrush x:Key="WindowBackground" Stretch="None" Opacity="0.6" ImageSource="pack://application:,,,/Resources/WindowBackground.jpg"/>

        <DataTemplate x:Key="ContainerItemTemplate">
            <Grid>
                <Border BorderThickness="1" BorderBrush="White" Margin="3">
                    <s:SurfaceTextBox IsReadOnly="True" Width="120" Text="{Binding Path=name}" Padding="3"/>
                </Border>
                <s:SurfaceButton Content="Expand" Click="SourceFilePressed"></s:SurfaceButton>
            </Grid>
        </DataTemplate>

    </s:SurfaceWindow.Resources>

然后我用它将ItemTemplate添加到LibraryContainer:

<Grid Name="RootGrid" Background="{StaticResource WindowBackground}" >
        <s:ScatterView Name="RootScatter">
            <Viewbox>
                <s:LibraryContainer Name="RootContainer" Grid.Row="0" ViewingMode="Bar">
                    <s:LibraryContainer.BarView>
                        <s:BarView Rows="2" NormalizedTransitionSize="2.5,0.8" ItemTemplate="{StaticResource ContainerItemTemplate}">
                        </s:BarView>
                    </s:LibraryContainer.BarView>
                    <s:LibraryContainer.StackView>
                        <s:StackView NormalizedTransitionSize="1,1" ItemTemplate="{StaticResource ContainerItemTemplate}">
                        </s:StackView>
                    </s:LibraryContainer.StackView>
                </s:LibraryContainer>
            </Viewbox>
        </s:ScatterView>
    </Grid>

稍后,我将向ScatterView添加一个新的ScatterView项:

ScatterViewItem item = new ScatterViewItem();

                FrameworkElement element = surfaceWindow as FrameworkElement;
                DataTemplate tmpl = element.FindResource("ContainerItemTemplate") as DataTemplate;


                LibraryContainer container = new LibraryContainer();
                container.ViewingMode = LibraryContainerViewingMode.Bar;
                container.ItemsSource = itms;
                container.BarView.ItemTemplate = tmpl;

                item.Content = container;
                surfaceWindow.getRootScatter().Items.Add(item);

不幸的是,我总是在行中遇到一个空引用异常:

container.BarView.ItemTemplate = tmpl;

在此方法中传递对象surfaceWindow。它是对我定义DataTemplate的文件的引用。