Keeping responsive UI

Question

I have a winform which have several combo boxes and a gridview.

Initially I am creating the gridview with Rows and Columns and no data filled in with.

enter image description here

The filling data to grid is a long running task which will loop through all rows and read column header and depending on that it will apply different color and data to each cell.

What I am trying to achieve is to load the grid as above in form load event, and after the form loaded start filling data to grid so user can see what happening. Same things apply to the combo box value change since I will load data according to the combo value.

What I have tried is something like this...

In form load I am calling method

 private void LoadForm()
        {                        
            DataBind(); // this will load the initial grid without cell data            

            this.BeginInvoke((MethodInvoker)this.LongRunningProcess1);

            this.BeginInvoke((MethodInvoker)this.LongRunningProcess2);

         }

But still it taking long time and I don't have the responsive UI.

I also tried something like this but no luck....

            ThreadStart ts = LongRunningProcess1;
            Thread t1 = new Thread(ts);
            t1.Start();

Also using a background worker to complete the long running operation causes "Cross thread operation" issue.

 private void backgroundWorker_DoWork(object sender, DoWorkEventArgs e)
        {
                LongRunningProcess1();
                LongRunningProcess2();           
        }

Any help to make this working is appreciate..

Thanks

UPDATE

I found a really cool solution Updating Your Form from Another Thread without Creating Delegates for Every Type of Update

Thanks for the answers!!!

I recommend you use a BackgroundWorker so you do the long running operation outside the UI thread. http://www.switchonthecode.com/tutorials/csharp-tutorial-using-the-backgroundworker-class — Phil, Jul 13 '12 at 08:34
Start by identifying what exactly takes a long time, down to the level of "this loop here, and specifically this call inside the loop". — Jon, Jul 13 '12 at 08:36
By the way, calling `this.BeginInvoke` won't help you with ANY long-running task - it just schedules your task in the UI event-loop and returns. This means that the task will be processed by GUI thread, still freezing your App. — undefined, Jul 13 '12 at 08:43

Nilzor · Answer 1 · 2012-07-13T13:27:16.587

To avoid the CrossThreadException in the completed-event of the background worker, wrap your callback method like this:

public void WorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
{
    if (this.InvokeRequired)
    {
        this.Invoke(new RunWorkerCompletedEventHandler(WorkerCompleted), new {sender, e});
    }
    else 
    {
        // Business logic goes here
    }
}

Typically you will populate the data loaded into the GridView in the else-block. If you on the other hand want to populate the GridView progressively from the long-running background task, you can achieve this with a similar technique using callbacks from the background worker:

public void Worker_DoWork(object sender, DoWorkEventArgs e)
{
   foreach (var someParameter in parameterList) // Long-running loop 
   {
     var data = LoadData(someParameter); // Load data for row X
     this.Invoke(new Action<object>(UpdateRow),new[]{data});  // Update on UI-thread
   }
}


public void UpdateRow(object data)
{
   // Code to populate DataGrid row X with data from argument
}

Note that you can call BeginInvoke instead of Invoke if you want to do the UI-updating asynchronously. This will usually not make a difference in this case.

Thanks Nilzor. So if I using background worker, I think i have to put my two long running methods with in DoWork event?? and call RunWorkerAsync within my LoadForm()... so what shoud I so in the else part you mention in your answer. please correct me if I am wrong !! — huMpty duMpty, Jul 13 '12 at 08:49
You are correct. The RunWorkerCompleted-event and method is optional. You typically put code in that block to populate the grid after the data is loaded. I have updated the answer also with tips on how to update the grid progressively — Nilzor, Jul 13 '12 at 13:28

score 0 · Answer 2 · answered Jul 13 '12 at 08:38

0

The backgroud worker process is the correct way to go, you just need to eliminate all the "Cross thread operation" exceptions by making sure that all the calls that modify the form elements use the Control.Invoke method wrapper.

answered Jul 13 '12 at 08:38

Bob Vale

18,094
1
42
49

score 0 · Answer 3 · edited May 23 '17 at 12:06

0

If you want to use the backgroundworker/multithreading, you can use delegates updating your form(they run on ui thread). See example here: How to update the GUI from another thread in C#?

edited May 23 '17 at 12:06

Community

1
1

answered Jul 13 '12 at 08:46

Zyn

1

score 0 · Answer 4 · answered Jul 13 '12 at 10:24

Simple example using BackgroundWorker and RunWorkerAsync. Hope this helps.

public partial class Form2 : Form
{

    BackgroundWorker worker = new BackgroundWorker();

    public Form2()
    {

        worker.WorkerReportsProgress = true;
        worker.WorkerSupportsCancellation = true;

        worker.DoWork += new DoWorkEventHandler(worker_DoWork);
        worker.RunWorkerCompleted += new RunWorkerCompletedEventHandler(worker_RunWorkerCompleted);
        worker.ProgressChanged += new ProgressChangedEventHandler(worker_ProgressChanged);

        InitializeComponent();
    }

    void worker_DoWork(object sender, DoWorkEventArgs e)
    {
        int totalSteps = 5;
        for (int i = 1; i <= totalSteps; i++)
        {
            Thread.Sleep(1000);
            worker.ReportProgress(i);
        }
    }

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

    void worker_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
    {
        resultText.Text = "Worker complete";
        btnDoWork.Enabled = true;
        progressBar1.Visible = false;
    }

    private void btnDoWork_Click(object sender, EventArgs e)
    {
        progressBar1.Visible = true;
        worker.RunWorkerAsync();
    }

}

Keeping responsive UI

4 Answers4