How to Update a WPF UI from a Separate Thread in a Different Class?

Updating UI from a Separate Thread in a Different Class

Q: How to update a WPF UI from a worker thread running in a separate class?

A: To update the UI from a different thread:

1. Use Dispatcher.Invoke: Call this method within the worker class to update UI elements on the main thread.

2. Event-Based Communication:

   • Create events in the worker class to raise notifications of UI updates.
   • Register handlers for these events in the main window class.
   • Dispatch UI updates within the event handlers.

Example Using Events:

// Main window class
private void startCalc(object sender, RoutedEventArgs e)
{
    // Create a new worker class instance
    CalcClass calc = new CalcClass();
    
    // Register event handler to receive UI update notifications
    calc.ProgressUpdate += (s, e) =>
    {
        Dispatcher.Invoke((Action)(() => { /* Update UI here */ }));
    };
    
    // Start the worker thread
    Thread calcThread = new Thread(new ParameterizedThreadStart(calc.TestMethod));
    calcThread.Start(input);
}

// Worker class
public class CalcClass
{
    public event EventHandler ProgressUpdate;

    public void TestMethod(object input)
    {
        // Perform calculations
        
        // Raise event to notify UI update
        if (ProgressUpdate != null)
            ProgressUpdate(this, new EventArgs());
    }
}

Additional Note:

Alternative Solution Using Task:
In .NET 4.5 and later, you can also use asynchronous programming with Task to update the UI in a cleaner and more efficient way.

Updated Code Using Task:

// Main window class
private async void buttonDoCalc_Clicked(object sender, EventArgs e)
{
    // Create a new worker class instance
    CalcClass calc = new CalcClass();
    
    // Start the asynchronous calculation
    await calc.CalcAsync();
}

// Worker class
public class CalcClass
{
    public async Task CalcAsync()
    {
        // Perform calculations
        
        // Update UI using Dispatcher.Invoke
        Dispatcher.Invoke((Action)(() => { /* Update UI here */ }));
    }
}

The above is the detailed content of How to Update a WPF UI from a Separate Thread in a Different Class?. For more information, please follow other related articles on the PHP Chinese website!