event handling for composite controls

Posted on 2012-03-22
Last Modified: 2012-04-09
Hi Experts,

I am trying to build a windows form composite control. As of now the composite control only has one text box. In the contianing client (another windows form) I would like to be able to access the value entered in the textbox.

Should I create a event to be triggered when focus leaves the composite control (the text box for now). How do I do that?

Is there any other way to deal with this?

thanks in advance
Question by:Mydeen Yussouf
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LVL 86

Expert Comment

by:Mike Tomlinson
ID: 37755086
You either directly publicly expose the TextBox (not recommended), or create a Public property to access the Text() property of the TextBox contained within.  So you just basically "wrap" the Text() property of the TextBox in your own Property at the UserControl level.

Author Comment

by:Mydeen Yussouf
ID: 37759016
Hi @idle_mind, thanks. I am sorryif I was not clear, but I am able to access the text box value as a public property of the composite control, but my current challenge is this. If it were a regular text box I would use the leave event of the control to check if the value has changed or not and update the underlying business model. Here I need a event to do the same. This is thinking along the lines of what I currently have. What other option is there with a composite control? thanks

Author Comment

by:Mydeen Yussouf
ID: 37759065
Come to think of it, I could use some events like, when the form is closed or when the save button is clicked, for now, but I would like to understand how events are done in composite controls, thanks
LVL 86

Accepted Solution

Mike Tomlinson earned 500 total points
ID: 37759318
Not sure what you're after here...

This is an example of raising a custom "leave" event for the UserControl when the TextBox's Leave() event fires:
    public partial class UserControl1 : UserControl

        public delegate void TextBoxLeaveDelegate(Object sender);
        public event TextBoxLeaveDelegate TextBoxLeave;

        public string TextBoxValue
            get { return textBox1.Text; }

        public UserControl1()

        private void textBox1_Leave(object sender, EventArgs e)
            if (TextBoxLeave != null)


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