About Extending the Functionality of Visio
You can extend the functionality of Microsoft Visio in the following ways:
Create Visio-specific macros and add-ons.
Create COM (Component Object Model) add-ins.
Macros and add-ons are programs that extend the functionality of Visio. Exactly how you run a macro or add-on depends on the context for which it was designed.
You can run a macro or add-on from the Visio application in several ways. Here are a few of the most common:
Choose a macro or add-on from the Macros dialog box. (In the Code group on the Developer tab, click Macros.) If your program is an EXE file, before it can appear in the Macros dialog box, it must be located in a folder along the Add-ons path in the File Locations dialog box. (Click the File tab, click Options, click Advanced, and then, under General, click File Locations.)
Starting with Microsoft Office Visio 2003, instead of specifying file paths to your Visio add-ons, you can publish your add-ons by using a Microsoft Windows Installer package. By doing so, you can take advantage of Microsoft Office application features such as language switching, installation on demand, and repair. For more information about using a Windows Installer package to publish your add-ons, search for "Microsoft Windows Installer" on MSDN, the Microsoft Developer Network Web site.
Double-click a shape associated with an add-on or macro. The program you want to run must be selected in the Run macro list on the Double-Click tab in the Behavior dialog box for that shape. (Select the shape, and then, on the Developer tab, click Behavior).
Right-click a shape, and then click a custom menu item for an add-on or macro on the shortcut menu. The program associated with the custom menu item must be entered in the Actions section of the ShapeSheet window for the shape.
If an add-on is designed to be run outside the Visio application, you run it like any Microsoft Windows-based program (for example, by double-clicking an icon on the desktop). For details, see your Windows documentation.
Beginning with Visio 2002, you can use COM add-ins in the same standardized way as in other Microsoft Office applications. The COM add-in must be registered with the Visio application and can work in multiple applications. For example, you can build a COM add-in that performs the same task in Visio and Microsoft Excel, or any of the Microsoft Office applications. You can create COM add-ins with Microsoft Visual Basic 5.0 and higher, Microsoft C++, Microsoft Office 2000 Developer Edition and higher, or any of the Microsoft Visual Studio .NET applications.
For more information about building COM add-ins, see MSDN.