Changing a form from a separate background worker

问题

I have a form which when loaded starts a looping background worker which gets data from a usb device every half a second.
Once the program receives a new piece of data from the usb device it runs a function.
The _Dowork function has

while (true)
{
    portConnection.Write("?");
    Thread.Sleep(50);
}

I then have a separate routine that runs when data is received

private void portConnection_DataReceived(object sender, SerialDataReceivedEventArgs e)
{
}

This is the routine that cannot then set values on the original form as the function is apparently on a separate thread.
How can I make this routine able to influence the original form?

回答1:

Try something like this:

private void InvokeIfRequired(Control target, Delegate methodToInvoke)
{
    if (target.InvokeRequired)
        target.Invoke(methodToInvoke);
    else
        methodToInvoke.DynamicInvoke();
}

Call the method in your ProcessStatsReceived and in the methodToInvoke do your stuff...

You can use it like this in the ProccessStatusReceived:

InvokeIfRequired(this, new MethodInvoker(delegate() { this.lblStatus.Text = (string)e.Data; }));

回答2:

The report progress part of BackgroundWorker is made for this.

This will make the DoWork method able to call a method on the GUI thread.

See this msdn article for details.

In short, the needed parts are:

Bind the progress changed handler:

bw.ProgressChanged += bw_ProgressChanged;

Set the BW to allow progress reporting:

bw.WorkerReportsProgress = true;

Implement the progress change method:

private void bw_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
  //your logic to be executed on the GUI thread here
}

Then call it from DoWork like this:

bw.ReportProgress( progressPercentage, userState )

progressPercentage and userState can be user to transfer data from the background thread to the ProgressChanged method on the GUI thread.

来源：https://stackoverflow.com/questions/11842373/changing-a-form-from-a-separate-background-worker