IMultiValueConverter Interface
Assembly: PresentationFramework (in presentationframework.dll)
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.
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:c="clr-namespace:SDKSample" x:Class="SDKSample.Window1" Width="400" Height="280" Title="MultiBinding Sample"> <Window.Resources> <c:NameList x:Key="NameListData"/> <c:NameConverter x:Key="myNameConverter"/> ... </Window.Resources> ... <TextBlock Name="textBox2" DataContext="{StaticResource NameListData}"> <TextBlock.Text> <MultiBinding Converter="{StaticResource myNameConverter}" ConverterParameter="FormatLastFirst"> <Binding Path="FirstName"/> <Binding Path="LastName"/> </MultiBinding> </TextBlock.Text> </TextBlock> ... </Window>
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.
Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition
The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.Reference
IMultiValueConverter MembersSystem.Windows.Data Namespace