CODEWITHSUNDEEP
c#winformsmultithreadingparallel-processing
eMi
eMi

Reputation: 5618

C# Threading, 1st Task DoSomething, 2nd Task update a WinFormLabel (Realtime)?

Lets say I have Task 1:

private void Task1()
{
    //Here is some Code, could be any "longer" Task - 
    //For Example: Grab all words from a .txt File and fill in a List<String>
}

Then I have an other Task 2:

private void Task2(string word)
{
   //So lets say theres a Label on my WinForm..
   //Now While Task1 is grabbing the words, Task2 should fill a Label 
   //with the added 'word' (parameter) - (Task2 will be called from Task1
}

Actually I don't know how to make this possible, or whats the best way. On the UI I should be able to see the Label.Text changing (every word).. So I need to make a second Thread? How could I do this? Maybe someone could help me, cheers

UPDATE:

I tried it now with the Backgroundworker, but something seems to be false.. its actually not working, nothing happens on the form

Code:

public void CreateAndSaveAMatch(DateTime date) //That method is being called several times
{   
    //HERE IS CODE, WHICH CREATES AND SAVES A MATCH

    // Start the asynchronous operation.
    backgroundWorker1.RunWorkerAsync(date);

}

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{      
    backgroundWorker1.ReportProgress(0, Convert.ToDateTime(e.Argument).ToShortDateString());          
}

private void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    label1.Text = (string)e.UserState; //here on the Label I would like to show the Date
}

Upvotes: 0

Views: 577

Answers (4)

Nikola Davidovic
Nikola Davidovic

Reputation: 8656

Ok, try this. This is a simple example that will show you how to solve your problem using BackgroundWorker. Also note that there are many other solutions. To use this example create a Form in a new project that only has a button and a label. Also note that this is a supplement of the other answers which were correct.

public partial class Form1 : Form
    {
        BackgroundWorker createAndSaveAMatchBGW;
        public Form1()
        {
            InitializeComponent();
            createAndSaveAMatchBGW = new BackgroundWorker();
            createAndSaveAMatchBGW.DoWork += new DoWorkEventHandler(createAndSaveAMatchBGW_DoWork);
            createAndSaveAMatchBGW.ProgressChanged += new ProgressChangedEventHandler(createAndSaveAMatchBGW_ProgressChanged);
            createAndSaveAMatchBGW.RunWorkerCompleted += new RunWorkerCompletedEventHandler(createAndSaveAMatchBGW_RunWorkerCompleted);
            createAndSaveAMatchBGW.WorkerReportsProgress = true;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            createAndSaveAMatchBGW.RunWorkerAsync(DateTime.Now);
        }

        void createAndSaveAMatchBGW_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            MessageBox.Show("BackgroundWorker finished");
        }

        void createAndSaveAMatchBGW_ProgressChanged(object sender, ProgressChangedEventArgs e)
        {
            label1.Text = ((DateTime)e.UserState).ToString("ss");
        }

        void createAndSaveAMatchBGW_DoWork(object sender, DoWorkEventArgs e)
        {
            //BackgroundWorker does something for a 10 seconds, each second it Reports
            BackgroundWorker bgw = (BackgroundWorker)sender;
            DateTime dt = (DateTime) e.Argument;
            for (int i = 0; i < 10; i++)
            {
                Thread.Sleep(1000);
                dt = dt.AddSeconds(1);
                bgw.ReportProgress(0, dt);
            }
        }
    }

And if you report from CreateAndSave... method only once per its execution, then you can use this code:

BackgroundWorker createAndSaveAMatchBGW;
        public Form1()
        {
            InitializeComponent();
            createAndSaveAMatchBGW = new BackgroundWorker();
            createAndSaveAMatchBGW.DoWork += new DoWorkEventHandler(createAndSaveAMatchBGW_DoWork);
            createAndSaveAMatchBGW.RunWorkerCompleted += new RunWorkerCompletedEventHandler(createAndSaveAMatchBGW_RunWorkerCompleted);
        }

        private void button1_Click(object sender, EventArgs e)
        {
            createAndSaveAMatchBGW.RunWorkerAsync(DateTime.Now);
        }

        void createAndSaveAMatchBGW_RunWorkerCompleted(object sender, RunWorkerCompletedEventArgs e)
        {
            label1.Text = ((DateTime)e.Result).ToString();
        }

        void createAndSaveAMatchBGW_DoWork(object sender, DoWorkEventArgs e)
        {
            DateTime dt = (DateTime) e.Argument;
            //you do something with your DateTime
            dt = dt.AddDays(10);
            e.Result = dt;
        }

Upvotes: 2

Sergey Berezovskiy
Sergey Berezovskiy

Reputation: 236208

Use BackgroundWorker for reporting progress from first task. Drag this component from toolbox to your form, and subscribe to DoWork and ProgressChanged events. Also set property WorkerReportsProgress to true. Then start you first task asynchronously:

// this will execute code in `DoWork` event handler
backgroundWorker1.RunWorkerAsync();

Next - use userState object to pass processed words:

private void backgroundWorker1_DoWork(object sender, DoWorkEventArgs e)
{      
    // grab words in a loop and report progress
    backgroundWorker1.ReportProgress(0, word);
}

And last step - update label in ProgressChanged event handler

void backgroundWorker1_ProgressChanged(object sender, ProgressChangedEventArgs e)
{
    label1.Text += (string)e.UserState; // this is your grabbed word
}

Upvotes: 2

Eric J.
Eric J.

Reputation: 150108

The simplest way to achieve this kind of thing is using BackgroundWorker.

http://msdn.microsoft.com/en-us/library/system.componentmodel.backgroundworker.aspx

BackgroundWorker automatically handles thread marshalling and provides events that allow you to update the UI. The event handlers run on the UI thread.

The things you do in Task1 could be moved into a BackgroundWorker, and the updates to the UI that you propose to do in Task2 can actually be in response to progress events from BackgroundWorker.

ProgressChangedEventArgs provides for user-defined data that could hold the current word.

However, Winforms (and indeed pretty much any UI) will not be able to keep up with a separate CPU thread just loading words from a file if you intend to show every word you load.

Upvotes: 1

Justin Niessner
Justin Niessner

Reputation: 245399

Task1 could be started on a separate thread.

You wouldn't actually need a Task2 unless there was some complex logic being performed to update the TextBox. You you really need to do is use TextBox.Invoke() to invoke the update on the UI Thread from Task1.

Upvotes: 0

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