संपादित करें

इसके माध्यम से साझा किया गया

ItemsControl.ItemTemplateSelector Property

  • Reference

Definition

Namespace:
System.Windows.Controls
Assembly:
PresentationFramework.dll

Gets or sets the custom logic for choosing a template used to display each item.

public:
 property System::Windows::Controls::DataTemplateSelector ^ ItemTemplateSelector { System::Windows::Controls::DataTemplateSelector ^ get(); void set(System::Windows::Controls::DataTemplateSelector ^ value); };
[System.ComponentModel.Bindable(true)]
public System.Windows.Controls.DataTemplateSelector ItemTemplateSelector { get; set; }
[<System.ComponentModel.Bindable(true)>]
member this.ItemTemplateSelector : System.Windows.Controls.DataTemplateSelector with get, set
Public Property ItemTemplateSelector As DataTemplateSelector

Property Value

DataTemplateSelector

A custom DataTemplateSelector object that provides logic and returns a DataTemplate. The default is null.

Attributes
BindableAttribute

Examples

In the following example, the auctionItemDataTemplateSelector resource name (corresponding to an AuctionItemDataTemplateSelector class) is assigned to the ItemTemplateSelector property of the ItemsControl.

<ItemsControl 
   Template="{StaticResource ScrollTemplate}" 
   ItemsSource="{Binding Source={StaticResource items_list}}"
   ItemTemplateSelector="{StaticResource auctionItemDataTemplateSelector}" >
   <ItemsControl.ItemsPanel>
      <ItemsPanelTemplate>
         <StackPanel />
      </ItemsPanelTemplate>
   </ItemsControl.ItemsPanel>
</ItemsControl>

The following example shows the implementation of the AuctionItemDataTemplateSelector class with an override of the SelectTemplate method:

using System.Windows;
using System.Windows.Controls;

namespace SDKSample
{
    public class AuctionItemDataTemplateSelector : DataTemplateSelector
    {
        public override DataTemplate 
            SelectTemplate(object item, DependencyObject container)
        {
            FrameworkElement element = container as FrameworkElement;

            if (element != null && item != null && item is AuctionItem)
            {
                AuctionItem auctionItem = item as AuctionItem;
                Window window = Application.Current.MainWindow;

                switch (auctionItem.SpecialFeatures)
                {
                    case SpecialFeatures.None:
                        return 
                            element.FindResource("AuctionItem_None") 
                            as DataTemplate;
                    case SpecialFeatures.Color:
                        return 
                            element.FindResource("AuctionItem_Color") 
                            as DataTemplate;
                }
            }

            return null;
        }
    }
}


Namespace SDKSample
    Public Class AuctionItemDataTemplateSelector
        Inherits DataTemplateSelector
        Public Overrides Function SelectTemplate(ByVal item As Object, ByVal container As DependencyObject) As DataTemplate

            Dim element As FrameworkElement = TryCast(container, FrameworkElement)

            If element isnot Nothing andalso item IsNot Nothing AndAlso TypeOf item Is AuctionItem Then

                Dim auctionItem As AuctionItem = TryCast(item, AuctionItem)

                Select Case auctionItem.SpecialFeatures
                    Case SpecialFeatures.None
                        Return TryCast(element.FindResource("AuctionItem_None"), DataTemplate)
                    Case SpecialFeatures.Color
                        Return TryCast(element.FindResource("AuctionItem_Color"), DataTemplate)
                End Select
            End If

            Return Nothing
        End Function
    End Class
End Namespace

In this case, within the SelectTemplate method of the class, there is logic to return the appropriate template based on the value of the SpecialFeatures property of the item object passed. The template to return is found in the resources of the enveloping Window element.

When you set the ItemTemplateSelector property, the ItemsControl is directed to automatically call the SelectTemplate method of AuctionItemDataTemplateSelector for each of the items in the collection to which the ItemsControl is bound. The call passes the data item as an object. The DataTemplate that is returned by the method is then used to display that data item.

For another example, see Data Templating Overview.

Remarks

You use the ItemTemplate to specify the visualization of the data objects. If you have more than one template defined and want to supply logic to return a template to use, then you use this property. Note that this property is ignored if ItemTemplate is set.

The ItemsControl provides great flexibility for visual customization and provides many styling and templating properties. Use the ItemContainerStyle property or the ItemContainerStyleSelector property to set a style to affect the appearance of the elements that contain the data items. For example, for ListBox, the generated containers are ListBoxItem controls; for ComboBox, they are ComboBoxItem controls. To affect the layout of the items, use the ItemsPanel property. If you are using grouping on your control, you can use the GroupStyle or GroupStyleSelector property.

For more information, see Data Templating Overview.

XAML Attribute Usage

<object ItemTemplateSelector="ResourceExtension SelectorResourceKey"/>

XAML Values

ResourceExtension One of the following: StaticResource, or DynamicResource. Unless the styles themselves contain references to potential run-time references such as system resources or user preferences, StaticResource reference to a style is usually recommended for performance.

SelectorResourceKey x:Key string value referring to the selector being requested as a resource.

Dependency Property Information
Identifier field ItemTemplateSelectorProperty
Metadata properties set to true None

Applies to

See also