Ytukyg

I have a multiline Textbox that uses threadsafe method to call it.
After every new text, the caret ( cursor ) goes to first line position and for multiline texts. I can't read the lasts lines.

I try to use:

 textBox.CaretIndex = _textBox.Text.Length;

but it is not for threadsafe.

This is my code:

void test()

{

Thread demoThread =

               new Thread(new ThreadStart(this.ThreadProcSafe));

            demoThread.Start();

}

private void ThreadProcSafe()

{

    ThreadHelperClass.SetText(this, textBox2, "text: ");

}

public static class ThreadHelperClass{

    delegate void SetTextCallback(Form f, Control ctrl, string text);

    /// <summary>

    /// Set text property of various controls

    /// </summary>

    /// <param name="form">The calling form</param>

    /// <param name="ctrl"></param>

    /// <param name="text"></param>

    public static void SetText(Form form, Control ctrl, string text){

        // InvokeRequired required compares the thread ID of the 

        // calling thread to the thread ID of the creating thread. 

        // If these threads are different, it returns true. 

        if (ctrl.InvokeRequired){

            SetTextCallback d = new SetTextCallback(SetText);

            form.Invoke(d, new object { form, ctrl, text });

        } else {

            ctrl.Text += text;

            ctrl.Text += Environment.NewLine;

        }

    }

}

ThreadHelperClass.SetText(this, richTextBox1, "output>>" + e.Data);

I want to go at end of the Textbox ( for see the last lines text ) without clicking or moving the mouse. After a new text, caret go to end of the line.

i want to use Setting cursor at the end of any text of a textbox at ThreadHelperClass but it gives me error

want to use

txtBox.Focus();

txtBox.SelectionStart = txtBox.Text.Length;

OR

txtBox.Focus();

txtBox.CaretIndex = txtBox.Text.Length;

OR

txtBox.Focus();

txtBox.Select(txtBox.Text.Length, 0);

this is the error that I get when i using above codes in ThreadHelperClass
Severity Code Description Project File Line Suppression State
Error CS0120 An object reference is required for the non-static field, method, or property 'Form1.textBox2' Download C:UsersworksourcereposDownloadDownloadForm1.cs 108 Active

and when I use it outside of this function my application get crashed for multi thread

Can you try calling textBox.CaretIndex = _textBox.Text.Length; from the GUI thread like this:

Application.Current.Dispatcher.Invoke(

    () =>

    {

         textBox.CaretIndex = _textBox.Text.Length;

    });

Problem Solved By using
Cross-thread operation not valid: Control 'textBox1' accessed from a thread other than the thread it was created on

delegate void SetTextCallback(string text);



private void SetText(string text)

{

  // InvokeRequired required compares the thread ID of the

  // calling thread to the thread ID of the creating thread.

  // If these threads are different, it returns true.

  if (this.textBox1.InvokeRequired)

  { 

    SetTextCallback d = new SetTextCallback(SetText);

    this.Invoke(d, new object { text });

  }

  else

  {

    this.textBox1.Text = text;

  }

}

in this way I can use textbox and all sub commands like Focus, Select in Cross-thread operation without crash.

txtBox.Focus();

txtBox.Select(txtBox.Text.Length, 0);

but in my Question Code there was a

Control ctrl

that didn't have Select, Focus
like to know the answer for old way too

Anyway Thanks