CODEWITHSUNDEEP
multithreadingc#-4.0timer
Sandun Perera
Sandun Perera

Reputation: 581

Cross thread violation error inside Timer_Tick event

My WinForm application invokes a thread to run a process, and also starts a WinForms Timer control Tick event at same time to display the progress of the thread process.

    public void threadTimer_Tick(object sender, EventArgs e)
    {
        lblProgessCount.Text = countDownText;
    }

countDownText is a static string variable which is get updated from the thread process and time to time I want to display the latest value in it in a UI label control. But it gives me the below error,

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

But the timer is started outside the thread process. Can anyone explain how to solve this issue.

Upvotes: 0

Views: 94

Answers (1)

Darin Dimitrov
Darin Dimitrov

Reputation: 1039438

But the timer is started outside the thread process.

But you are manipulating the UI inside the timer callback. Here you are attempting to modify the UI from a different thread:

lblProgessCount.Text = ...

You should use the Invoke method to ensure that this action is marshaled to the main UI thread:

public void threadTimer_Tick(object sender, EventArgs e)
{
    Action setValue = () => lblProgessCount.Text = countDownText;
    this.Invoke(setValue);
}

Upvotes: 2

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