Call Form2 with Circular Progress Bar while another action is executed C#

Question

I have a question about a Windows Form call. In this application, through the button click event located in Form1, call a second Form, where in this form2 I present an animated Circular Progress Bar running until another method located in Form 1 called Carregargrid() is finalized.

At that time my application meets the following code:

Button Event located in Form 1:

public partial class frm_Painel_de_Producao : Form
{
 frm_Progress_Bar pb = frm_Progress_Bar();

    private async void btnAtualizaGrid_Click(object sender, EventArgs e)
    {

      pb.Show();

      //desabilita os botões enquanto a tarefa é executada.
      btnCancelar.Enabled = false;
      btnIncluir.Enabled = false;      
      btnAtualizaGrid.Enabled = false;

      // simply start and await the loading task
      await Task.Run(() => carregarGrid());
      pb.Close();

      // habilita os botões após  tarefa evento de loading.
      btnAtualizaGrid.Enabled = true;
      btnCancelar.Enabled = true;
      btnIncluir.Enabled = true;    

    }

 }

Form 2 code only Initialize:

public partial class frm_Progress_Bar : Form
{
    public frm_Progress_Bar()
    {
        InitializeComponent();

    }  
}

Form 2 Designer + Progress Bar:

Property of Form 2: Back Color = Fuchsia Transparency Key = Fuchsia

Property of Circular Progress Bar:

In this case in the properties already meets with Style: Mark Because Li somewhere that this property should be as Mark, "if I’m not mistaken to continue to give the effect of loading."

Form 1 Load Method:

public void carregarGrid()
    {

        timer.Interval = 1000;
        timer.Tick += meuRelogio;
        timer.Start();
        dgvProducao.AutoGenerateColumns = false;
        dgvProducao.DataSource = clsPPCP.painelProducao();
        MeuBD.AbreXML();
        if (MeuBD.RequerUsuario == "1")
        {
            txtOperador.Focus();
        }
        else
        {
            txtOperador.Hide();
            txtNomeOperador.Hide();
            label8.Hide();
            txtCartao.Focus();
        }
        colorirGrid();
        //MeuBDex.AbreXML();
        relogio();   
    }

With this information I now report the errors I found:

This error is happening because in the click event I am putting the following code: await Task.Run(() => carregarGrid());

With this occurs the legendary error: Invalid threaded operation: 'control' accessed from a thread that is not the one in which it was created.

I tried to redo this application then using Thread and Delegates but also did not succeed for lack of experience with Threads.

And once again I redid this application trying to point out in the Form2 Load Event, call the Form1 method loadGrid. Respecting the Form 1 instance creation in Form2. But I also did not succeed.

So I’ve come humbly to ask you how can I resolve this application? Doubts:

1- How best to work with Circular Progress Bar?

2- Do I use Progressbar in another Form as in the example above? Or I can put Progress Bar in the same Form1.

3- It would also be possible in the Form 1 Load Event to be calling the Load method and once the method is finished, Progressbar with Form2 is terminated?

I already leave my thanks for all the help. Thank you!

Answer 1

There are several ways to make the progress bar, but I believe that when it comes to Windows Forms, the ideal is to use the BackgroundWorker that performs the work in the background, leaving the form thread free to show progress in the bar.

I made an example of how it works:

private void button1_Click(object sender, EventArgs e)
{
    if (!backgroundWorker1.IsBusy) //se o bw não estiver ocupado...
    {
        int arg = 100000;
        backgroundWorker1.RunWorkerAsync(arg); //você pode passar um argumento pro bw
    }
}


private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{
    //iniciou o processo em segundo plano
    int total = (int)e.Argument;
    int valor = 0;
    for (int i = 0; i <= total; i++)
    {
        valor += i;

        int p = i * 100 / total; //calcula percentual do progresso

        backgroundWorker1.ReportProgress(p); //informa o percentual do progresso
    }

    e.Result = valor;
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    progressBar1.Value = e.ProgressPercentage; //exibe o percentual na barra
}

private void backgroundWorker1_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    //evento quando o processo é finalizado
    if (e.Cancelled)
    {
        //processo foi cancelado
        //tem que definir o bw pra suportar cancelamento e verificar a flag e.Cancel dentro do processo...
    }
    else if (e.Error != null)
    {
        //deu erro e foi lançada exceção
    }
    else
    {
        int resultado = (int)e.Result;
        MessageBox.Show("Resultado: "+ resultado);
    }
}

The above example answers questions 1 and 2. A 3, just fire bw after you open the form. Close the other form with the progressiBar no longer need...

To insert the BackGroundWorker just drag it from Toolbar:

And then place the events: