SkjoettNet

Sometimes its a good idea to spawn a new thread from the GUI, to do some heavy calculation or
other time consuming task, to avoid the GUI to freeze as the task is running.
When a thread has been spawned, it would often also be nice to recieve som kind of
feedback from the calculation, of progress and status.
It’s not possible for a thread that did not create the GUI to update it, therefore we have
to make a few tweaks to make progress information from the thread appear on the GUI.
Here is an example of how it could be done.

In the GUI (windows forms):

private delegate void DoRefreshProgressText(string info);
private Label progressText = new Label(); // could be e.g. a progressbar

CheckForIllegalCrossThreadCalls = false;
Calculator calculator = new Calculator();
calculator.reportInfo += new Calculator.ReportInfo(reportInfoToGUI);

void reportInfoToGUI(string infoString) {
    if (progressText.InvokeRequired) {
        DoRefreshProgressText d = new DoRefreshProgressText(reportInfoToGUI);
        Invoke(d, new object[] { infoString });
    } else {
        progressText.Text = infoString;
    }
}

In the spawned thread:

public class Calculator {
    public delegate void ReportInfo(string infoString);
    public event ReportInfo reportInfo;
    public void SomeMethodCalledByThread(string statusText) {
        if (reportInfo != null) {
            reportInfo(statusText);
        }
    }
}