Question

I develop a WinForms UserControl in C#.
The UserControl is essentially a composite control that consists of several child controls, e.g. a PictureBox, a CheckBox, a Label, etc.

From the calling code, I want to be able handling a Click event for my control.
However, I want the event raised if and only if the user clicks on a certain component of my control, e.g. the PictureBox. If the user clicks anywhere else within my control, the event should not be raised.

How can I do that?

Answer 1

Assuming you are using WinForms.

You should delegate a Click event from a pictureBox into your own event and then subscribe to it from the calling code.

public class MyControl : System.Windows.Forms.UserControl
{
    // Don't forget to define myPicture here
    ////////////////////////////////////////

    // Declare delegate for picture clicked.
    public delegate void PictureClickedHandler();

    // Declare the event, which is associated with the delegate
    [Category("Action")]
    [Description("Fires when the Picture is clicked.")]
    public event PictureClickedHandler PictureClicked;

    // Add a protected method called OnPictureClicked().
    // You may use this in child classes instead of adding
    // event handlers.
    protected virtual void OnPictureClicked()
    {
        // If an event has no subscribers registerd, it will
        // evaluate to null. The test checks that the value is not
        // null, ensuring that there are subsribers before
        // calling the event itself.
        if (PictureClicked != null)
        {
            PictureClicked();  // Notify Subscribers
        }
    }
    // Handler for Picture Click.
    private void myPicture_Click(object sender, System.EventArgs e)
    {
        OnPictureClicked();
    }
}