我如何使用Backgroundworker C＃更改其他形式的标签？

Question

I have 2 form (formA & formB) in my project c#, i want to run some process in backgroundworker when i click a button in formA.

can i update from backgroundworker to label in formB? here's the code in formA

        private void button1_Click_1(object sender, EventArgs e)
    {
        backgroundWorker1.RunWorkerAsync();
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {
        Stimulus stimulus = new Stimulus();
        Stopwatch watch = new Stopwatch();
        stimulus.Show();
        stimulus.Invoke((MethodInvoker)delegate { stimulus.perbaharuiStimulus("+"); });
        watch.Start();
        do
        {

        } while (watch.Elapsed.Seconds != 2);
        watch.Restart();
        stimulus.Invoke((MethodInvoker)delegate { stimulus.perbaharuiStimulus("MAJU"); });
        do
        {

        } while (watch.Elapsed.Seconds != 6);
        watch.Restart();
        stimulus.Invoke((MethodInvoker)delegate { stimulus.perbaharuiStimulus(""); });
        do
        {

        } while (watch.Elapsed.Seconds != 2);
        watch.Stop();
        stimulus.Close();
    }

and heres code in formB

        public Stimulus()
    {
        InitializeComponent();
        FormBorderStyle = FormBorderStyle.None;
        WindowState = FormWindowState.Maximized;
    }
    public void perbaharuiStimulus(string stimulus)
    {
        this.Invoke((MethodInvoker)delegate
        {
            lbStimulus.Text = stimulus;
        });
    }

thankyou for attention..

Answer 1

You can change your code like below and it'll work fine.

1. Change perbaharuiStimulus code to

    lbStimulus.Text = stimulus; 

2. Change WorkerReportsProgress to True

3. Change backgroundWorker1_DoWork to below

     Stimulus stimulus = new Stimulus(); Stopwatch watch = new Stopwatch(); backgroundWorker1.ReportProgress(1, stimulus); watch.Start(); do { } while (watch.Elapsed.Seconds != 2); watch.Restart(); backgroundWorker1.ReportProgress(2, stimulus); do { } while (watch.Elapsed.Seconds != 6); watch.Restart(); backgroundWorker1.ReportProgress(3, stimulus); do { } while (watch.Elapsed.Seconds != 2); watch.Stop(); stimulus.Invoke((MethodInvoker)delegate { stimulus.Close(); }); 

4. Add the backgroundWorker1_ProgressChanged event and put below code in it

    private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e) { Stimulus stimulus = ( Stimulus)e.UserState; if(e.ProgressPercentage==1) stimulus.perbaharuiStimulus("+"); if (e.ProgressPercentage == 2) stimulus.perbaharuiStimulus("MAJU"); if (e.ProgressPercentage == 3) stimulus.perbaharuiStimulus(""); stimulus.Show(); } 

I hope this help you!

Answer 2

You can update a label in any form from a background worker using Invoke(...) like you did it. (Assuming stimulus is a field). It is enough to call Invoke once. Stimulus.Invoke executes the delegate on the control thread of the stimulus form. So you can decide, whee you dispatch the thread. I'd recommend to do this in perbarauiStimulus , since that would reduce the chance that someone forgets to dispatch the call.

But there is one potential issues with your code:

Don't use exact comparison for elapsed time. Prefer using '>='. Since you are dealing with seconds this will rarely be an actual problem, but it may result in an infinite loop.

If stimulus isn't a field you have to create an instance of Stimulus outside of the background worker, because if you create it inside the worker Method, the form will run its message loop on the background workers thread. This eliminates the use of a background worker since the operation runs now synchronously from sytimulus view.

Answer 3

You shouldn't be creating the form in the background thread. Doing so will assign the form to that thread instead of the UI thread, meaning the form is now on a different thread than the message pump.

What you can do to fix this is to invoke the instantiation and viewing of the form on the UI thread, then your following Invoke calls should work.

Stimulus stimulus;

this.Invoke((MethodInvoker)delegate
{
    stimulus = new Stimulus();
    stimulus.Show();
});

//No need to invoke this since perbaharuiStimulus() calls Invoke() as well.
stimulus.perbaharuiStimulus("+");

//The rest of your code...

Apart from that you're doing everything correctly.