How to access form elements from outside the form class

[aatif]

I want to change the text of a textfield of a c# form object, but from outside that class. How can I do it?
By passing that form field as a reference? How can I pass a reference of that form or textfield to that function if I am running that function in a separate thread?

Thanx

[PRR]

I would rather keep UI and logic separate.... its better that way....
as for your question

a. You can pass as parameter the control id which you intend to change

public void ChangeText(System.Windows.Forms.Button t)
       {
           t.Text = "Bytes";
       }
 
Class my = new Class();           
 
            my.ChangeText(this.button1);
 
 

b. Or you could use Controls.Find method ...or you can loop through the controls in your class method ... You should give the form object as input method ...

 
public void ChangeSomething(System.Windows.Forms.Form myForm)
       {
 
           System.Windows.Forms.Control[]  bb = myForm.Controls.Find("button1", true);
 
           foreach (System.Windows.Forms.Control c in bb)
           {
               if (c.Name == "button1")
               {
                   c.Text = "CCC";
               }
           }
 
           //OR
 
           foreach (System.Windows.Forms.Control c in myForm.Controls)
           {
               if (c.Name == "button1")
               {
                   System.Windows.Forms.Button b = c as System.Windows.Forms.Button;
                   //b.Text = "Changed from class";
               }
           }
       }
 

In your form.cs on button click, you can call

Class my = new Class();
            my.ChangeSomething(this);
 

[aatif]

How can I check that the control which I am looking for exists in the 'Controls' list? The foreach loop fails to search by name.

[tlhintoq]

When you make the control on the target form, give it a meaningful name that you can look for from the other class.

[Bassem]

Don't forget,
If you're going to access a control from another thread than the one the control is created on, you'll face the cross-thread exception.
Check it by using IsInvokeRequired property!

[alexgm23]

You can use a delegate to get access to a control that is in another thread:

// This is an extract from a server/client socket program
 
delegate void SetTextCallback(String Text);
 
private void SetText(String Text)
{
    if (textBox1.InvokeRequired)
    {
        SetTextCallback d = new SetTextCallback(SetText);
        this.Invoke(d, new object[] { Text });
    }
    else
    {
        this.textBox1.Text = this.textBox1.Text + Text + "\r\n";
    }
}
 
public void OnDisconnect(IAsyncResult asyn)
{
    ((Socket)asyn.AsyncState).EndDisconnect(asyn);
    SetText(clientSocket.RemoteEndPoint.ToString() + " has disconnected!");
}
 

I hope this helps!!

Alex G.

[aatif]

Alex,
Sorry I couldn't get it, do you have an example?

Bassem,
where is IsInvokeRequired...?

[aatif]

ok, I am done.

public void UpdateText()
{
    Control[] ctrlResponse = isoAgentForm.Controls.Find("textStatus", true);
    if (!ctrlResponse[0].InvokeRequired)
    {
        ctrlResponse[0].Text = statusMsg;
    }
    else
    {
        ctrlResponse[0].Invoke(new ThreadStart(UpdateText));
    }
}

I also changed the textfield from private to public.



Any good suggestion?

[matasoy]

Most easy way is to change your element private to public on projects.cs

private System.Windows.Forms.Button button1;
private System.Windows.Forms.Button button2;
public System.Windows.Forms.Label label1;