DependencyProperty.RegisterReadOnly to create read only Dependency Property : DependencyProperty « Windows Presentation Foundation « C# / CSharp Tutorial

1. C# / CSharp Tutorial
2. Windows Presentation Foundation
3. DependencyProperty

<Window x:Name="winThis" x:Class="WpfApplication1.Window1"
  xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
  xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
  Title="Create a Read-Only Dependency Property" Height="300" Width="300">
    <Grid>
      <Viewbox>
        <TextBlock Text="{Binding ElementName=winThis, Path=Counter}" />
      </Viewbox>
    </Grid>
</Window>

//File:Window.xaml.cs
using System;
using System.Windows;
using System.Windows.Threading;

namespace WpfApplication1
{
    public partial class Window1 : Window
    {
        public Window1()
        {
            InitializeComponent();

            DispatcherTimer timer = 
                new DispatcherTimer(TimeSpan.FromSeconds(1), 
                                    DispatcherPriority.Normal, 
                                    delegate 
                                    {
                                        int newValue = Counter == int.MaxValue ? 0 : Counter + 1;
                                        SetValue(counterKey, newValue); 
                                    }, 
                                    Dispatcher);
        }

        public int Counter
        {
            get { return (int)GetValue(counterKey.DependencyProperty); }
        }

        private static readonly DependencyPropertyKey counterKey = 
            DependencyProperty.RegisterReadOnly("Counter", 
                                                typeof(int), 
                                                typeof(Window1), 
                                                new PropertyMetadata(0));
    }
}

24.150.DependencyProperty
	24.150.1.	DependencyProperty.RegisterReadOnly to create read only Dependency Property
	24.150.2.	Clear locally set values and restore the default values of dependency properties