CODEWITHSUNDEEP
c#backgroundworkerinvokerequired
NESHOM
NESHOM

Reputation: 929

Updating array of labels from backgroundworkers

I am trying to update an array of Labels which are on a form from a backgroundworker. Here is my code:

for (int i = 0; i < 6; i++)
{
    if (this.InvokeRequired)
    {
        this.Invoke((MethodInvoker)delegate
        {
            arrLabel[i].Text = values[i].ToString();
        });
    }
    else
    {
        arrLabel[i].Text = values[i].ToString();
    }
}

This does not work, but if I try to change text property of each label instead of the array, it works. How can I fix this? Also is there a shorter/better way of updating form controls from backgroundworkers than what I am doing for every single control on my form?

Edit: here is how I defined the array:

  private Label[] arrLabel = new Label[6];

and here is the function that I call to assign the array:

    private void makeLabelArrays()
    {
        for (int i = 0; i < 6; i++)
        {
            arrLabel[i] = (Label)Groupbox1.Controls["label" + (i + 1).ToString()];
        }
    }

Upvotes: 0

Views: 174

Answers (2)

Grant Winney
Grant Winney

Reputation: 66439

I'm assuming what some of your code looks like; I may be wrong.

You can use the ReportProgress() method to send two pieces of information back to the UI thread - the percentage of completeness (doesn't really apply in your case so I specified 0) and some piece of data (any object you want, just a number in this case).

Then you can get the data in the ProgressChanged event and execute code that touches the UI.

private List<Label> arrLabel = new List<Label>();
private List<string> values = new List<string>(); 

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    var bw = (BackgroundWorker)sender;

    for (int i = 0; i < 6; i++)
        bw.ReportProgress(0, i);
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    var currentIndex = Convert.ToInt32(e.UserState);

    arrLabel[currentIndex].Text = values[0].ToString();
}

Make sure you enable reporting progress, as it's disabled by default.

backgroundWorker1.WorkerReportsProgress = true;

Upvotes: 1

Srikanth
Srikanth

Reputation: 1010

try the following 

private delegate void delegateAssignText();

public void AssignText()
{
    if (this.InvokeRequired)
    {
        Invoke(new delegateAssignText(AssignText));
        return;
    }


    for (int i = 0; i < 6; i++)
    {
        arrLabel[i].Text = values[0].ToString();
    }
}

Upvotes: 1

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