nYou use the RegisterRoutine macro to identify a DLL routine to be called from the Help file as a Help macro.Help provides the following mechanisms for calling DLL routines:
nYou use the RegisterRoutine macro to identify a DLL routine to be called from the Help file as a Help macro.
nYou can create an embedded window in a topic and use a DLL to control the objects displayed in the embedded window.
Many Windows-based programs use DLLs. A DLL is a library of programming routines that is automatically loaded when needed. DLLs are useful because they can use memory efficiently, and their routines can be called from multiple applications.
Figure 14.3 illustrates the two DLL interfaces.
In the example, EWDEMO.DLL contains routines to display a list of printers in the special embedded window. MMLIB.DLL contains a PlayAudio routine that is registered in the Help project file and is called using a macro hot spot.
The following sections describe the two DLL interfaces. For important information about writing DLLs to support external macros and embedded windows, see Chapter 20, “Writing DLLs for Windows Help.”