Question

I am using a background worker to update some tables in sqlserver. the progressbar max is getting set to the correct value, the progressbar value is being incremented, the backgroundworker progresschanged is being called correctly with correct value, yet the bar is not progressing.

here is the code for the form
in the background_dowork method there is a loop which calls updateProgressBarValue which works with correct values.

public InterfaceConvertLonLat()
{
    InitializeComponent();
    Shown += new EventHandler(Form1_Shown);
    backgroundWorker1.WorkerReportsProgress = true;
    backgroundWorker1.ProgressChanged += new ProgressChangedEventHandler(backgroundWorker1_ProgressChanged);
    backgroundWorker1.DoWork += new DoWorkEventHandler(backgroundWorker1_DoWork);
}

public void ConvertLonLat_Load(object sender, EventArgs e)
{ 
}

public void updateProgressBarValue()
{
    progressBar1.Value++;
    backgroundWorker1.ReportProgress(progressBar1.Value);
}

public void setProgressBarMax(int max)
{
    progressBar1.Maximum = max;
    MessageBox.Show("setprogressbarmax " + max);
}

public void Form1_Shown(object sender, EventArgs e)
{     
    backgroundWorker1.RunWorkerAsync();
}

public void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    convert.OSGB36ToWGS84("paf");
}

public void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage;
}

here is the loop contained in another class which calls updateprogressbarvalue, this is being fired and as stated backgroundworker1_progressChanged is being fired but the bar is not moving.

con.setProgressBarMax(address.Tables[0].Rows.Count); 

foreach (DataRow LonLat in address.Tables[0].Rows)
{
    con.updateProgressBarValue();
    Double lon = 0;
    Double lat = 0;
    lat = Convert.ToDouble(LonLat["LTO"]);
    lon = Convert.ToDouble(LonLat["LGO"]);
    LocalToWGS84(ref lat, ref lon, OGB_M);

    cmd1.Parameters["@LTW"].Value = lat;
    cmd1.Parameters["@LGW"].Value = lon;

    string dbQuery1 = "update " + tableName + " set LTW = @LTW, LGW = @LGW";

    cmd1.CommandText = (dbQuery1);
    cmd1.CommandType = CommandType.Text;
    cmd1.Connection = conn;
    cmd1.ExecuteNonQuery();
}
}
catch (Exception e)
{
    MessageBox.Show("error converting: " + e.Message);
}
finally
{
    conn.Close();
}

Answer 1

When reporting progress you need to fire an event from the background worker to tell the progressbar it needs updating. This can be done using the below:

backgroundWorker1.ReportProgress(10);

Change the value to what you need to demonstrate increased progress in your code. The progress changed event will mostly run on the same thread as your GUI so you should have no cross thread issues. One exception is if your form is being called from Excel via addin in which case Excel will be on the main thread.