Programming Visual Basic 2005

Using the Custom Controls

Your custom control (RolodexPanel) will be housed within a form. The base form will be frmRolodex, whose job will be to provide common code for all the specialized forms (e.g., frmCustomerRolodex).

Back in the NorthWindWindows project, add a new form, frmRolodex. Set its size to 976,615. Open the Toolbox and expand the NorthWindControls Components section. Drag a RolodexPanel onto the new form, and drag a label named lblDisplay above it, as shown in Figure 4-6.

Everything in frmRolodex will be shared by all its derived types. You want to factor all the elements common to the derived forms into this form, so they will be as simple (and maintainable) as possible.

You need two members:

Protected orderedBy As String
Protected infoTable As Data.DataTable

The first, orderedBy, will keep track of the sort order for the data table. The second, infoTable, will hold a reference to a DataTable (e.g., the Customers table).

There are three event handlers you must create: one for when the form is loaded, the second for when the RowFillEvent is fired by the RolodexPanel, and the third for when the ButtonSelectedEvent is fired by the RolodexPanel.

When the form is loaded, you'll call LoadRolodex, a helper method, as shown in Example 4-12.

Figure 4-6. Adding RolodexPanel to frmRolodex

Example 4-12. Rolodex form Load event handler

Private Sub frmRolodex_Load( _ ByVal sender As System.Object, ...