Question

I have two threads.

Thread 1: WPF thread. Shows a Window with all the information.
Thread 2: Loops constantly, receiving information & updates the Window in thread 1.

I have the following interfaces.

IModuleWindow
{
    void AddModule(IModule module);
    void RemoveModule(IModule module);
}

IModule
{
    UserControl GetSmallScreen();
    UserControl GetBigScreen();
}

IModuleWindow is implemented by the WPF window in Thread 1
IModule is implemented by an object, is instantiated in Thread 2, and then sent to thread 1.

I want to Add the UserControls in IModule to the Window object in thread 1, and show them. IModule objects get updated constantly in thread 2 and they have to change their text.

Basically the idea is that this program is supposed to show the state of objects in thread 2 , which gets updated constantly.

What is the best way to accomplish this in WPF?

Answer 1

IMO the best idea is to use BackgroundWorker, with the very handy ReportProgress method and ProgressChanged event.

The ProgressChanged event is raised on the GUI thread, so you can perform your updates to the GUI directly. Here’s how you code should look like:

// initialize the worker
BackgroundWorker backgroundWorker1 = new BackgroundWorker();
backgroundWorker1.WorkerReportsProgress = true;
backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
backgroundWorker1.RunWorkerAsync();


// thread 2 (BackgroundWorker) 
private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    // main loop
    while(true) 
    {
        // time-consuming work
        // raise the event; use the state object to pass any information you need
        ReportProgress(0, state);
    }
}

// this code will run on the GUI thread
private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    // get your state back
    object state = e.UserState;
    // update GUI with state
}