Logo Questions Linux Laravel Mysql Ubuntu Git Menu
 

How can data templates in generic.xaml get applied automatically?

I have a custom control that has a ContentPresenter that will have an arbitrary object set as it content. This object does not have any constraint on its type, so I want this control to display its content based on any data templates defined by application or by data templates defined in Generic.xaml. If in a application I define some data template(without a key because I want it to be applied automatically to objects of that type) and I use the custom control bound to an object of that type, the data template gets applied automatically. But I have some data templates defined for some types in the generic.xaml where I define the custom control style, and these templates are not getting applied automatically. Here is the generic.xaml :

<DataTemplate DataType="{x:Type PredefinedType>
    <!-- template definition -->
<DataTemplate>

<Style TargetType="{x:Type CustomControl}">
    <!-- control style -->
</Style>

If I set an object of type 'PredefinedType' as the content in the contentpresenter, the data template does not get applied. However, If it works if I define the data template in the app.xaml for the application thats using the custom control.

Does someone got a clue? I really cant assume that the user of the control will define this data template, so I need some way to tie it up with the custom control.

like image 877
Thiago Padilha Avatar asked May 01 '10 22:05

Thiago Padilha


People also ask

What is data template in XAML?

Data template is a bit of XAML that describes how bound data is displayed. A data template can contain elements that are each bound to a data property along with additional markup that describes layout, color and other appearance.

What is difference between a control template and DataTemplate in WPF?

A ControlTemplate will generally only contain TemplateBinding expressions, binding back to the properties on the control itself, while a DataTemplate will contain standard Binding expressions, binding to the properties of its DataContext (the business/domain object or view model).

What are data templates in WPF?

DataTemplate is about the presentation of data and is one of the many features provided by the WPF styling and templating model. For an introduction of the WPF styling and templating model, such as how to use a Style to set properties on controls, see the Styling and Templating topic.

What is a data template?

The data template is the method by which you communicate your request for data to the data engine. It is an XML document whose elements collectively define how the data engine will process the template to generate the XML. The data engine supports the following functionality: Single and multiple data queries.


1 Answers

Resources declared in Generic.xaml are only pulled in if they are directly referenced by the template being applied to a control (usually by a StaticResource reference). In this case you can't set up a direct reference so you need to use another method to package the DataTemplates with your ControlTemplate. You can do this by including them in a more local Resources collection, like ControlTemplate.Resources:

<Style TargetType="{x:Type local:MyControl}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:MyControl}">
                <ControlTemplate.Resources>
                    <DataTemplate DataType="{x:Type local:MyDataObject}">
                        <TextBlock Text="{Binding Name}"/>
                    </DataTemplate>
                </ControlTemplate.Resources>
                <Border BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}"
                        Padding="{TemplateBinding Padding}" Background="{TemplateBinding Background}">
                    <ContentPresenter/>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>
like image 197
John Bowen Avatar answered Sep 23 '22 10:09

John Bowen