Programming Visual Basic 2005

Custom Controls

So far, you have created user controls, which are essentially reusable web page fragments.^[*] You can also create your own compiled custom controls . As noted earlier, there are three ways to create custom controls :

• Create a derived custom control by deriving from an existing control.

• Create a composite control by grouping existing controls together into a new control.

• Create a full custom control by deriving from System.Web.UI.WebControls.WebControl.

The custom controls most similar to user controls are the composite controls. The key difference is that composite controls are compiled into a DLL and used as you would any server control you find in the Toolbox.

Creating a Web Control Library

To get started, you'll create a Web Control Library in which you'll place the various custom controls for this chapter. Open Visual Studio .NET and choose New Project. In the New Project Window, create a Web Control Library called CustomControls, as shown in Figure 13-4.

After clicking OK, you'll notice that Visual Studio has created a complete custom control named WebCustomControl1 . Before examining this control, create a web application to test it. Right-click on the solution in the Solution explorer and choose Add → New Web Site. Set the name of your web site to CustomControlTester. Your solution now includes two projects: a web site (with Default.aspx) and a Custom Controls library (with WebCustomControl1.vb).

Web Custom Control 1

Web Custom Control 1 is a full custom control, ...