Accessing control from another class and thread

Simon

Hi there,

I could use some help with the following issue:

I have a Form which has a public TextBox member... that form loads up a new thread which is defined in a separate class.

The thread has a constant loop in it.. and I need to update the textbox on my form with messages obtained at the end of each cycle in that loop.. in C++ that would be easy with just passing a few pointers when I create the thread class.. but in C# I have to enagle unmanaged code and still I can't really pass the textbox as a pointer... so I'm looking for some other solution if there is one.. (tried messing with the ActiveForm and such but can't really get it going)

Any quick help would be awsome.. :P

Thanks

5 Replies

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Rasmus Striib16y ago
Accepted answer
You could do it like this:
Note that I have simply written the code here in the editor - but it should compile.
namespace MyNamespace
{
public class Form1 : System.Windows.Forms.Form
    {
      public System.Windows.Forms.TextBox m_log;
        Worker workerObject;
        Thread workerThread;
    private void startthread()
           {
                workerObject = new Worker(m_log);
                workerThread = new Thread(new ThreadStart(workerObject.DoWork));
                workerThread.Start();
           }
     }

   public class Worker
{
    private TextBox textBox;
    public Worker(Textbox textBox)
   {
       this.textBox = textBox;
    }
    public void DoWork()
    {
      while (!_shouldStop)
          {

            //I need to set the value of the Text property for my m_log TextBox from the other class and I don't have an instance of that class here...
            SetText("Hello World!");
           }
     }
    private delegate void SetTextDelegate(string text);
    private void SetText(string text)
   {
      if (textbox.InvokeRequired)
      {
          SetTextDelegate d = new SetTextDelegate(SetText);
          textBox.Invoke(d, new object[] { text });
       }
       else
       {
           textBox.Text = text;
        }
    }
}
}
Simon16y ago
Works perfectly :)
Thanks for the help

Cheers
Deepak Bhatia16y ago
Sorry first of all for delay in answer.
There were light problems here due to heavy rainfall. Just wait a bit I will post an working example on how to do it.
This would help you out.
Simon16y ago
Hi,

I forgot to mention that I'm using .net 1.1 :D
That one has some form of delegates aswell though I don't quite get how they work
My application's structure looks like this, I'll leave out the usual stuff so this is just a sketch:

namespace MyNamespace
{
public class Form1 : System.Windows.Forms.Form
    {
      public System.Windows.Forms.TextBox m_log;
        Worker workerObject;
        Thread workerThread;
    private void startthread()
           {
                workerObject = new Worker();
                workerThread = new Thread(new ThreadStart(workerObject.DoWork));
                workerThread.Start();
           }
     }
public class Worker
{
    public void DoWork()
    {
      while (!_shouldStop)
          {

            //I need to set the value of the Text property for my m_log TextBox from the other class and I don't have an instance of that class here...
           }
     }
}
}

My question is.. how do I do this using delegates?

Thanks for the quick reply
Deepak Bhatia16y ago
Use event and delegates to do it.
In C# it is possible to use cross thread functionalities using events and delegates.
Just see simple example
http://www.akadia.com/services/dotnet_delegates_and_events.html
http://www.codeproject.com/KB/cs/events.aspx
If you have problem just reply, I will help you out.