ActiveX Designers and the Component Object Model

COM, on which ActiveX and OLE technologies are based, is a standard that defines how applications expose objects. Using this standard, you can create classes that comply with the COM model. ActiveX compound documents and ActiveX controls are two such classes; ActiveX designers represent a third.

Because ActiveX designers are based on COM, they provide several significant benefits:

• They fit neatly into the existing architecture.
  
  
• They make it easy for programmers to create classes that comply with the COM standard.
  
  
• They simplify and streamline the development process by hiding complexity from the programmer.

The following figure shows how ActiveX designers fit into COM:

An ActiveX designer can be as simple as an object that makes itself visible at design time, or as complex as a form that hosts controls.

ActiveX designers and ActiveX controls share the following characteristics:

• They can have different behavior at design time and at run time. An ActiveX designer need not have a visible user interface at run time.
  
  
• They can be attached to code written by an end user.
  
  
• They can be compiled into an executable application.

By adding code to register the object appropriately, you can create an ActiveX designer from an ActiveX control.