Occurs before the control becomes visible for the first time.
Assembly: System.Windows.Forms (in System.Windows.Forms.dll)
You can use this event to perform tasks such as allocating resources used by the control.
If the UserControl is part of an MDI child form, the event will occur each time the child form is shown. In this case, you should put any one-time initialization code in the UserControl instead of a event handler.
The event occurs when the handle for the UserControl is created. In some circumstances, this can cause the event to occur more than one time. For example, the event occurs when the UserControl is loaded, and again if the handle is recreated. (One way that a handle is recreated is by calling the RecreateHandle method.) To account for the event occurring more than one time, you should put any one time initialization code in the UserControl constructor instead of a event handler. In addition, you should not add data bindings to the UserControl in a event handler.
For more information about handling events, see Consuming Events.
The following code example demonstrates the use of this member. In the example, an event handler reports on the occurrence of the event. This report helps you to learn when the event occurs and can assist you in debugging. To report on multiple events or on events that occur frequently, consider replacing MessageBox.Show with Console.WriteLine or appending the message to a multiline TextBox.
To run the example code, paste it into a project that contains an instance of type UserControl named UserControl1. Then ensure that the event handler is associated with the event.
Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)
The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.