Subclassing and Hooking with Visual Basic

Superclassing a Control

Superclassing a control is similar to superclassing a WinForm. First, you write a new class that inherits from the control that you want to superclass; for the following example, it will be a button control. Next, you override the WndProc for the control and add your own functionality.

The application

This example application contains a text box and a superclassed button control on the WinForm. Table 22-6 lists the nondefault properties of the form and its controls. Figure 22-6 presents a screenshot of the application. When you right-click the superclassed button, a message box is displayed indicating that the button was, in fact, right-clicked.

Table 22-6. Nondefault Properties of the Form and Its Controls

Object	Property Name	Property Value
Form	Caption	“VB.NET Control Superclassing Example”
Form	Height	357
Form	Width	328
SCButton	Caption	“SC”
SCButton	Top	170
SCButton	Left	8
SCButton	Height	40
SCButton	Width	40

Figure 22-6. The application containing the superclassed button control

The .VB file

Example 22-8 presents the code for this technique. The important modifications to the code are in boldface.

Example 22-8. The Form1.vb File for Superclassing a Button Control

Imports System.ComponentModel Imports System.Drawing Imports System.WinForms Public Class Form1 Inherits System.WinForms.Form Public Sub New( ) MyBase.New( ) Form1 = ...