Irantha Jayasekara
Irantha Jayasekara
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December 02, 2014

Change WPF window label content from another class and a separate thread

By Irantha
C# Programming

Once I was working on a WPF application, I had a label called "Status_label" in MainWindow.xaml. I wanted to change its content from a different class (signIn.cs).

<Label HorizontalAlignment="Left" Margin="14,312,0,0" Name="status_lable" Width="361"/>

To change MainWindow.xaml label content from different class:
var mainWin = Application.Current.Windows.Cast<Window>().FirstOrDefault(window => window is MainWindow) as MainWindow;
mainWin.status_lable.Content = "Irantha signed in";

It worked fine !

So next, I wanted to make this from a different thread:
Then I experienced this;
"The calling thread cannot access this object because a different thread owns it."
Whenever you update your UI elements from a thread other than the main thread, you will see this error. I overcome this issue by,

Dispatcher.Invoke(new Action(() => { status_lable.Content = "Irantha signed in"; }));

From both different thread and another class;
The situation was changed and I needed to achieve both above scenarios together, I needed to access MainWindow.xaml label from a different class which is created on different thread rather than in main thread. I came a cross the following solution.

Hope this helps you. Please comment your thoughts. If you have a problem ask here, I'll try my best to help you. Or we can discuss each other.
Author Details
Irantha Jayasekara
Irantha Jayasekara

Software Developer, Web Developer, Freelancer, Project Manager & Google Apps Scripts and API expert

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