Accessing UserControls' controls events

[cyrak]

I am working on a C# application and I've created UserControls to make it easier to manage all the GUI's components.

I have one very simple user control consisted of a button and a textbox, this simple control is added on-the-fly when the user clicks on "add control" on a form that holds a collection of this controls. The button on the UserControl is to remove itself from the panel.

My question is, how can I tell on the form that is being added that the event was triggered for the button in the userControl ? because I need to remove that specific control from the form and the event happens in the userControl....
any suggestions ?

[misza]

My question is, how can I tell on the form that is being added that the event was triggered for the button in the userControl ?

Hi,

One of the way of doing this would be:

- add a public event to your user control, let's say CloseRequested (this event could have e.g. a current's control id as a parameter)

- inside your control subscribe to button's Clicked event and inside the handler fire the CloseRequested event

- each time you're adding a new control on runtime, you need to subscribe to CloseRequested event

... and voila: the handler on your main form will know when the user tries to close the control

- a nice thing to do would be also to unsubscribe from the CloseRequested event when closing the user control, just for cleaning purposes;)

hope this helps,

pls let me know if you need more details or code examples,

best regards,
Michal

[cyrak]

Hi,

One of the way of doing this would be:

- add a public event to your user control, let's say CloseRequested (this event could have e.g. a current's control id as a parameter)

- inside your control subscribe to button's Clicked event and inside the handler fire the CloseRequested event

- each time you're adding a new control on runtime, you need to subscribe to CloseRequested event

... and voila: the handler on your main form will know when the user tries to close the control

- a nice thing to do would be also to unsubscribe from the CloseRequested event when closing the user control, just for cleaning purposes;)

hope this helps,

pls let me know if you need more details or code examples,

best regards,
Michal

Im gonna have to take you on that offer of examples..I am a little confused on how to create a custom event handler..and how to trigger it mostly...so if it is possible, I would appreciate it,
thanks in advance!

[misza]

Hi Cyrak,

See the examples below;

In the file with your user control:

public delegate void CloseRequestedDelegate(int id); // define the delegate
 
public class UserControl
{
   /* (...) */
 
   private int m_id; // populated e.g. in the constructor
 
   /* control's published event */
   public event CloseRequestedDelegate CloseRequested; // define the event
 
   /* event handler to button's click event*/
   private void button1_Click(object sender, EventArgs e)
   {
        CloseRequested(this.m_id);
   }
}
 

The line below has to be put after InitializeComponent method (in constructor) or somewhere in UserControl's OnLoad event:
button1.Click += new System.EventHandler(this.button1_Click);

and code related to adding the control on runtime and subscribing to the event

(...)
/* CloseRequested event handler */
private void CloseRequestedHandler(int id) // has to have the same parameters and return value as CloseRequestedDelegate
{
  /* your code handling the CloseRequested event */
  System.Windows.Forms.MessageBox.Show("A control of id: " + id + " just requested to be closed");
}
 
(...)
// adding the control on runtime
UserControl ctrl = new UserControl(); 
ctrl.CloseRequested += new CloseRequestedDelegate(this.CloseRequestedHandler); // subscribe to the control's event
/* (...) your code */
 

in order to unsubscribe from that event just do this:
ctrl.CloseRequested -= this.CloseRequestedHandler;


I didn't compile/test the code, so it could have some issues invisible at first sight;)

good luck,
Michal