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Form Control

© Swapna Kamat

We have studied the concept of event and controls in our earlier articles. Let us elaborate on that in this article. We start with the elements of form control.

Form Events

Visual Basic forms and controls can trigger dozens of events in your applications. Forms, controls, and classes all have events. Let's look at some of the events for forms, and examine how and when they occur.

To demonstrate form events, we create a new form and placed code like this in the event procedure for each of the events:

Private Sub Form_Load()
Debug.Print "Load"
End Sub

For each event, the name of the event was sent to the debug window. Here was the output:

Initialize
Load
Resize
Activate
Paint
' I closed the form here
QueryUnload
Unload
Terminate

There are other form events also, such as the click event, etc., but those must be triggered by user actions or other code. These are the events that are always triggered for forms and the generic order in which they occur. Let's take a look at each.

• Initialize
  This event occurs as the form is being loaded, but before the Load event. It gives you the opportunity to initialize data that must be available when the form is loading.
• Load
  Load is the event most often used to initialize any dynamic components of the form, such as private data, control arrays, or any other element of the design that needs to be setup at run time rather than in design view.
• Resize
  This event occurs whenever the window state (windowed, minimized, or maximized) changes or whenever the form window is resized by the user. Here is where you place code that is dependent on the form size or window state. If, for example, you are building a text editor, you might resize a text box to the internal size of the form in the Resize event.
• Activate
  This event occurs whenever the form window gets the input focus. If you have code that tracks the active form in the application, you might use this event for that code.
• Paint
  This is where VB actually draw the form on the screen. If you are drawing directly on the form with graphics methods, that code might go in this event.
• QueryUnload
  This event is fired when the form is closed. You can use the event to determine the way the form is being closed (through your own code, by the user, or by Windows) and can also cancel the event and prevent the form from