BackgroundWorker - Form Refresh

Question

I'm trying to make it so that my form refreshes when I click a button. However I keep getting an error

'Cross-thread operation not valid: Control 'Form1' accessed from a thread other than the thread it was created on.'

 private void button1_Click(object sender, EventArgs e)
    {
        worker.DoWork += formReload;
        worker.RunWorkerAsync();
    }

    static BackgroundWorker worker = new BackgroundWorker();

    private void formReload(object sender, DoWorkEventArgs ev)
    {
        this.Refresh();
    }

    private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
    {

    }

I've tried to research it, and I get that I have to use the Invoke method, however I don't understand where to put it, and why to use it? Any help would be much appreciated!

Thanks, Jarrod

post some code of DoWork, you have to put it into that method. — Tobia Zambon, Jul 09 '13 at 13:25
possible duplicate of [Cross-thread operation not valid: Control accessed from a thread other than the thread it was created on](http://stackoverflow.com/questions/142003/cross-thread-operation-not-valid-control-accessed-from-a-thread-other-than-the) — Tim, Jul 09 '13 at 13:27
Hi, thanks for the fast reply. I have nothing in DoWork, so I posted the this.Refresh(); in there, however now there's no error, but it doesn't work either. What I have in my code is a variable, and in the form_load there's a switch case, so if the variable = 1, then do the code that's in case 1. — Jarrod, Jul 09 '13 at 13:30
I did try to google the error, hence why I know about the invoke method, however I didn't understand it, nor where to put it. — Jarrod, Jul 09 '13 at 13:31

Tobia Zambon · Accepted Answer · 2013-07-09T13:39:36.930

4

Actually your code does nothing, the DoWork is unnecessary. You can rewrite your code as:

private void button1_Click(object sender, EventArgs e)
{
    worker.RunWorkerAsync();
}

static BackgroundWorker worker = new BackgroundWorker();

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    if (this.InvokeRequired)
        this.Invoke(new Action(()=>Refresh()));
}

Assuming that you subscribed the DoWork method in the contructor using

worker.DoWork += backgroundWorker1_DoWork;

Take note that a Refresh doesn't change anything. What do you have to refresh?

edited Jul 09 '13 at 13:39

answered Jul 09 '13 at 13:27

Tobia Zambon

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Hi, thanks! The error doesn't appear anymore, but the form doesn't seem to be reloading – Jarrod Jul 09 '13 at 13:35
I've edited the reply, what do you have to reload? Where is the code to reload the form? – Tobia Zambon Jul 09 '13 at 13:40
What I thought it'd do was refresh everything (even in form_load). Because I have a int called refresh, so everytime the form is refreshed is adds one. Then my idea was to run a switch which gets the refresh int and draw different things in each case? If that makes sense – Jarrod Jul 09 '13 at 13:43
the Form_Load is called only once (when the form is actually loaded the first time). If you want to call it you don't have to use the `Refresh` but call it explicitly: use `this.Invoke(new Action(()=>form_Load(null,null)));` – Tobia Zambon Jul 09 '13 at 13:46
Thankyou very much :) Sorry for wasting your time – Jarrod Jul 09 '13 at 13:49
No Problem, I see you are new here: if the answer fits your need please mark it as accepted (put the green tick under the answer's score), thank you – Tobia Zambon Jul 09 '13 at 13:52

BackgroundWorker - Form Refresh

1 Answers1