Simplified TextBox focus in WPF 4

While prepping for some session I have to present, I started revisiting WPF 4 and taking a deeper look at what's new! One of the new markup extensions I noticed is the {x:Reference …} markup extension!

“References an instance that is declared elsewhere in XAML markup. The reference refers to an element's x:Name.”

So, where is this used! One of the first scenarios that comes to mind is the focus target… In WPF 3.0/3.5, If I wanted to associate keyboard shortcut with setting focus on a TextBox, I needed to write the following code.

WPF 3.0/3.5

<Window x:Class="WpfApplication5.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Label Content="_Name:" Target="{Binding ElementName=nameTextBox}" 
               Grid.Row="0" Grid.Column="0" />
        <TextBox x:Name="nameTextBox" 
               Grid.Row="0" Grid.Column="1" Width="200" />
        <Label Content="_Surname:" Target="{Binding ElementName=surnameTextBox}" 
               Grid.Row="1" Grid.Column="0" />
        <TextBox x:Name="surnameTextBox" 
               Grid.Row="1" Grid.Column="1" Width="200" />
    </Grid>
</Window>

With WPF 4.0, this has become way easier… check this out.

WPF 4.0

<Window x:Class="WpfApplication5.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Label Content="_Name:" Target="{x:Reference nameTextBox}" 
               Grid.Row="0" Grid.Column="0" />
        <TextBox x:Name="nameTextBox" 
               Grid.Row="0" Grid.Column="1" Width="200" />
        <Label Content="_Surname:" Target="{x:Reference surnameTextBox}" 
               Grid.Row="1" Grid.Column="0" />
        <TextBox x:Name="surnameTextBox" 
               Grid.Row="1" Grid.Column="1" Width="200" />
    </Grid>
</Window>

And if the property you are binding to is marked with System.Windows.Markup.NameReferenceConverter:

<Window x:Class="WpfApplication5.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        Title="MainWindow" Height="350" Width="525">
    <Grid>
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="Auto" />
        </Grid.ColumnDefinitions>
        <Label Content="_Name:" Target="nameTextBox" 
               Grid.Row="0" Grid.Column="0" />
        <TextBox x:Name="nameTextBox" 
               Grid.Row="0" Grid.Column="1" Width="200" />
        <Label Content="_Surname:" Target="surnameTextBox" 
               Grid.Row="1" Grid.Column="0" />
        <TextBox x:Name="surnameTextBox" 
               Grid.Row="1" Grid.Column="1" Width="200" />
    </Grid>
</Window>

[NOTE] If you try this in WPF 3.5, you will get a “'UIElement' type does not have a public TypeConverter class.” exception message.

Simple, isn’t it?

CodeProject