Question

I’m trying to bind a Label’s ‘Content’ property to a property from some custom type I have; unfortunately, I didn’t figure out how to do it, and that’s why I’m here 🙂

Let’s assume that I have the following type (can be in the same namespace as my WPF Window that contains the Label or different namespace):

namespace MyNS
{
    public class Person
    {
        private int age = 0;

        public int Age
        {
            get { return age; }
        }

        public void GetOlder
        {
            age++;
        }
    }
}

1. How to I bind my Label to ‘Age’ property?

2. At runtime I will create an instance of ‘Person’; I want to make sure that my Label is bound to the right instance; i.e. if I called:

   Person SomePerson = new Person();
   SomePerson.GetOlder();
   

   I want my Lable to have the new value of ‘Age’ property for ‘SomePerson’.

3. What if I called ‘GetOlder’ in different thread (whether using Dispatcher thread or BackgroundWorker)? Will I still get the latest value of ‘Age’? Or do I have to take care of some other things as well to make this scenario possible?

Thanks in advance,

TheBlueSky

Answer 1

It turned out to be kind of straightforward thing, I wonder why nobody answered it 🙂 Anyway, here are the answers:

1. First we need to create our Person class like this:

   using System.ComponentModel;
   
   namespace MyNS
   {
       public class Person : INotifyPropertyChanged
       {
           public event PropertyChangedEventHandler PropertyChanged;
   
           private int age = 0;
   
           public int Age
           {
               get { return age; }
               set
               {
                   age = value;
                   OnPropertyChanged("Age");
               }
           }
   
           protected void OnPropertyChanged(string PropertyName)
           {
               PropertyChangedEventHandler handler = PropertyChanged;
               if (handler != null)
               {
                   handler(this, new PropertyChangedEventArgs(PropertyName));
               }
           }
   
           public void GetOlder
           {
               Age++;
           }
       }
   }
   

2. Then we bind our WPF control to Person.Age property like this:

   using System.Windows.Data;
   
   //...
   
   Person p = new Person();
   Binding ageBinding = new Binding("Age");
   ageBinding.Source = p;
   MyWpfLabelControl.SetBinding(Label.ContentProperty, ageBinding);
   

   Now whenever p.GetOlder() is called MyWpfLabelControl.Content will change to the new p.Age value.

3. In multi-threading, the story is not different; it’ll work the same way when calling p.GetOlder() in a different thread:

   new Thread(
       new ThreadStart(
           delegate() {
               p.GetOlder();
           }
   )).Start();
   

Hope this helps.

TheBlueSky