VB Shell Programming

Creating a Context Menu Handler

Let’s put all of this into action and actually implement a context menu handler for the .rad file. We’ll add a context menu item that displays the noise an animal makes in a message box. The menu item itself will be displayed in the format (Animal Name) Noise . Animal Name will be determined from the .rad file in question. Let’s begin.

Type Library

The first step to creating the .rad file context menu handler is to compile the type library containing the interface definitions and constants that will be needed from VB. Constants and UDTs will also be put into the type library with their associated interfaces. But only the groups of constants that are needed will be put in the library. For instance, we need the menu constants MF_BYPOSITION, MF_STRING, and MF_SEPARATOR. Therefore, the library will contain all of the MF_ constants. We don’t need any of the menu state constants (MFS_ ), so they will not be included with the library.

The complete listing for the type library that will be used throughout the course of this book can be found in Appendix A. To compile the library, you need to have MKTYPLIB in your path. MKTYPLIB takes one argument on the command line, the name of the ODL file containing the type library definition. To compile, simply type:

mktyplib vbshell.odl

from the command line. If everything is in order, this should produce a file named vbshell.tlb. This is the type library.

To use this library from Visual Basic, you should select Project ...