Question

I dont know how to explain it .. so I decided to give image which will clear scenario.
I want to update label in my Usercontrol to get update from other thread which is started from main application. I learn dependency object help this singleton pattern lot but confused how to get it done spent almost one week :(.

Some time STA thread issue comes some time calling from other thread error occur.

Answer 1

Instead of making a static class TaskProgress to inherit from DependencyObject you should implement INotiifyPropertyChanged in it and raise PropertyChanged event from the setter of the property Instance.

This will do the trick because of two reasons…

1. DependencyObject is thread agnostic and hence access to it via some other thread will surely result in error.

2. INotifyPropertyChanged.PropertyChanged event is internally delegated to UI dispatcher by Binding framework of WPF. So a simple myTaskProgress.Instance = value will update the UI automatically no matter which thread it was done from.

Note that INotifyPropertyChanged being an interface, it cannot be implemented on static class and cannot have static event or static property. You will hav to have some instance of TaskProgress (like myTaskProgress above) bound to the Label.

Let me know if this helps.