Go Up to Help System Interfaces
System.HelpIntfs.IHelpSystem allows an application to do 3 things:
- Provides path information to the Help Manager.
- Provides a new Help selector.
- Asks the Help Manager to display Help.
Providing the help file name and path information is important because the Help Manager is platform-independent and Help system-independent and so is not able to ascertain the location of Help files. Therefore, an application must provide the Help file information through the Vcl.Forms.TApplication.HelpFile or Vcl.Forms.TForm.HelpFile method. This allows the Help file information to become available through the IHelpManager's GetHelpFile method.
Assigning a Help selector AssignHelpSelector allows the Help Manager to delegate decision making in cases where multiple external Help systems can provide Help for the same context ID. For more information, see the topic Implementing IHelpSelector.
IHelpSystem exports 5 methods to request the Help Manager to display Help:
Hook is intended entirely for HTMLHelp compatibility; it allows processing of
WM_HELP messages that cannot be mapped directly onto requests for keyword-based, context-based, or topic-based Help. (For more information, see MSDN for topics about HTMLHelp and WinHelp.) The other methods each take 2 arguments: the keyword, context ID, or topic name for which help is being requested, and the Help file in which it is expected that help can be found.