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Provides a way to apply custom logic in a MultiBinding.

Namespace: System.Windows.Data
Assembly: PresentationFramework (in presentationframework.dll)

Public Interface IMultiValueConverter
Dim instance As IMultiValueConverter

public interface IMultiValueConverter
public interface IMultiValueConverter
Schnittstellen können in XAML nicht direkt implementiert werden. Informationen finden Sie unter Typen, die diese Schnittstelle implementieren.

To associate a converter with a MultiBinding, create a class that implements the IMultiValueConverter interface, and then implement the Convert and ConvertBack methods.

Individual bindings in the collection can have their own value converters. For more information, see IValueConverter.

MultiBinding allows you to bind a binding target property to a list of source properties and then apply logic to produce a value with the given inputs. This example demonstrates how to use MultiBinding.

In the following example, NameListData refers to a collection of PersonName objects, which are objects that contain two properties, firstName and lastName. The following example produces a TextBlock that shows the first and last names of a person with the last name first.

  Title="MultiBinding Sample">
    <c:NameList x:Key="NameListData"/>
    <c:NameConverter x:Key="myNameConverter"/>


    <TextBlock Name="textBox2" DataContext="{StaticResource NameListData}">
        <MultiBinding Converter="{StaticResource myNameConverter}"
          <Binding Path="FirstName"/>
          <Binding Path="LastName"/>


To understand how the last-name-first format is produced, let's take a look at the implementation of the NameConverter:

Public Class NameConverter
    Implements IMultiValueConverter

Public Function Convert1(ByVal values() As Object, _
                         ByVal targetType As System.Type, _
                         ByVal parameter As Object, _
                         ByVal culture As System.Globalization.CultureInfo) As Object _
                         Implements System.Windows.Data.IMultiValueConverter.Convert
    Select Case CStr(parameter)
        Case "FormatLastFirst"
            Return (values(1) & ", " & values(0))
    End Select
    Return (values(0) & " " & values(1))
End Function

Public Function ConvertBack1(ByVal value As Object, _
                             ByVal targetTypes() As System.Type, _
                             ByVal parameter As Object, _
                             ByVal culture As System.Globalization.CultureInfo) As Object() _
                             Implements System.Windows.Data.IMultiValueConverter.ConvertBack
    Return CStr(value).Split(New Char() {" "c})
End Function
End Class

NameConverter implements the IMultiValueConverter interface. NameConverter takes the values from the individual bindings and stores them in the values object array. The order in which the Binding elements appear under the MultiBinding element is the order in which those values are stored in the array. The value of the ConverterParameter attribute is referenced by the parameter argument of the Converter method, which performs a switch on the parameter to determine how to format the name.

For the complete sample, see Implementing Parameterized MultiBinding Sample.

For another example of an IMultiValueConverter implementation, see Data Binding Demo.

Microsoft .NET Framework 3.0 wird unter Windows Vista, Microsoft Windows XP SP2 und Windows Server 2003 SP1 unterstützt.

.NET Framework

Unterstützt in: 3.0