WPF: Binding an integer to a TextBlock with TemplateBinding

Question

I have a custom control in WPF. In this I have a DependencyProperty of the type integer. In the template for the custom control I have a TextBlock, I and would like to show the value of the integer in the TextBlock. But I can't get it to work.

I'm using TemplateBinding. If I use the same code but change the type of the DependencyProperty to string it works fine. But I really want it to be an integer for the rest of my application to work.

How can I do this?

I've written simplified code that shows the problem. First the custom control:

public class MyCustomControl : Control
{
    static MyCustomControl()
    {
        DefaultStyleKeyProperty.OverrideMetadata(typeof(MyCustomControl), new FrameworkPropertyMetadata(typeof(MyCustomControl)));

        MyIntegerProperty = DependencyProperty.Register("MyInteger", typeof(int), typeof(MyCustomControl), new FrameworkPropertyMetadata(0));
    }


    public int MyInteger
    {
        get
        {
            return (int)GetValue(MyCustomControl.MyIntegerProperty);
        }
        set
        {
            SetValue(MyCustomControl.MyIntegerProperty, value);
        }
    }
    public static readonly DependencyProperty MyIntegerProperty;
}

And this is my default template:

<Style TargetType="{x:Type local:MyCustomControl}">
    <Setter Property="Template">
        <Setter.Value>
            <ControlTemplate TargetType="{x:Type local:MyCustomControl}">
                <Border BorderThickness="1" CornerRadius="4" BorderBrush="Black" Background="Azure">
                    <StackPanel Orientation="Vertical">
                        <TextBlock Text="{TemplateBinding MyInteger}" HorizontalAlignment="Center" />
                    </StackPanel>
                </Border>
            </ControlTemplate>
        </Setter.Value>
    </Setter>
</Style>

And usage:

<Window x:Class="CustomControlBinding.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:CustomControlBinding"
    Title="MainWindow" Height="350" Width="525">
<Grid>
    <local:MyCustomControl Width="100" Height="100" MyInteger="456" />
</Grid>

What am I doing wrong?

Thanks // David

Answer 1

Try using a regular Binding with a RelativeSource of TemplatedParent:

<TextBlock Text="{Binding MyInteger, RelativeSource={RelativeSource TemplatedParent}}" HorizontalAlignment="Center" />

According to this thread, this is a limitation of TemplateBinding:

TemplateBinding is a lightweight "binding", it doesn't support some features of traditional Binding, such as automatically type conversion using the known type converters associated with the target property