MessageBox progress using Form

Question

I'm starting to use C# and I'm trying to create something similar to a messageBox to show the progress while my application is working. My app gets the entries from a database and adds that data to a grid.

After a lot of searching, I've found a way to do it without freezing the UI; using Threads:

ProgressDialog progressDialog = new ProgressDialog();

progressDialog.ProgressMax = (int)total;

Thread backgroundThread = new Thread(
    new ThreadStart(() =>
    {
        try
        {
            psp_grid.DataSource = null;
            psp_grid.Rows.Clear();

            progressDialog.Title = "Cargando listado...";
            progressDialog.Status = "Se está cargando el listado de juegos. Por favor espere...";
            progressDialog.Message = "Recuperando juegos de la base de datos";

            using (SQLiteCommand cmd = new SQLiteCommand(query, handle))
            {
                using (SQLiteDataReader rdr = cmd.ExecuteReader())
                {
                    while (rdr.Read())
                    {
                        progressDialog.ProgressActual = Actual;
                        progressDialog.Message = "Añadidos " + Actual + " juegos de " + total;
                        psp_grid.Rows.Add();
                        psp_grid.Rows[psp_grid.RowCount - 1].Cells[0].Value = (Int64)rdr["ID"];
                        psp_grid.Rows[psp_grid.RowCount - 1].Cells[1].Value = (byte[])rdr["ICON0"];
                        psp_grid.Rows[psp_grid.RowCount - 1].Cells[2].Value = "Hola Primo
" + rdr["ID"].ToString() + (string)rdr["TITLE"];

                        switch (int.Parse(rdr["RATE"].ToString()))
                        {
                            case 1:
                                psp_grid.Rows[psp_grid.RowCount - 1].Cells[3].Value = GameStation_Game_Manager.Properties.Resources._1star;
                                break;

                            case 2:
                                psp_grid.Rows[psp_grid.RowCount - 1].Cells[3].Value = GameStation_Game_Manager.Properties.Resources._2star;
                                break;

                            case 3:
                                psp_grid.Rows[psp_grid.RowCount - 1].Cells[3].Value = GameStation_Game_Manager.Properties.Resources._3star;
                                break;

                            case 4:
                                psp_grid.Rows[psp_grid.RowCount - 1].Cells[3].Value = GameStation_Game_Manager.Properties.Resources._4star;
                                break;

                            case 5:
                                psp_grid.Rows[psp_grid.RowCount - 1].Cells[3].Value = GameStation_Game_Manager.Properties.Resources._5star;
                                break;

                        }

                        if (psp_grid.RowCount > 7 && changed == false)
                        {
                            psp_grid.Columns[2].Width = 434;
                            changed = true;
                        }

                        Actual++;
                    }
                }
            }

            psp_grid.Rows[0].Cells[0].Selected = true;
        }

        catch (Exception ex)
        {
            System.Diagnostics.Debug.Write(ex.ToString());
        }

        if (progressDialog.InvokeRequired)
            progressDialog.BeginInvoke(new Action(() => progressDialog.Close()));
    }));

// Start the background process thread
backgroundThread.Start();

// Open the dialog
progressDialog.ShowDialog();

That code is working fine on final program, but while debugging, it fails at second run and I want to learn the best way to do it without errors.

The error is (in Spanish):

Activado    Evento  Hora    Duración    Subproceso
Excepción: Se detectó una excepción: "System.InvalidOperationException" en System.Windows.Forms.dll ("Operación no válida a través de subprocesos: Se tuvo acceso al control '' desde un subproceso distinto a aquel en que lo creó."). Se detectó una excepción: "System.InvalidOperationException" en System.Windows.Forms.dll ("Operación no válida a través de subprocesos: Se tuvo acceso al control '' desde un subproceso distinto a aquel en que lo creó.") 12,02s      [11616]

I think the problem is because I add the entries from another thread, but I don't know how I can fix it.

Can someone help me?

Thanks!!

ElectroBit · Accepted Answer

Microsoft explains how to make thread-safe calls.

Here is the example from their website:

private delegate void SetTextCallback(string text);

private void SetText(string text)
{
    if (textBox1.InvokeRequired)
    {   
        SetTextCallback d = new SetTextCallback(SetText);
        Invoke(d, new object[] { text });
    }
    else
    {
        textBox1.Text = text;
    }
}



private void ThreadProcSafe()
{
    SetText("This text was set safely.");
}

MessageBox progress using Form

Answers (2)

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