Libhelp Interface

Calling libhelp from your application

The libhelp system provides just one interface procedure get_help for accesing help files written in HTML and accessible in the libhelp search path. This procedure can be directly called or be used as a callback procedure for Xt toolkit callbacks (can be casted to XtCallbackProc).

#include <help.h>
void get_help (Widget    parent, 
               XtPointer call_data, 
               XtPointer client_data);

After the Xt toolkit is initialized, the application calls get_help as needed.

Parameter

Widget parent
arbitrary managed or realized widget, for example the toplevel shell. It is used to determine the display. If called as callback it is the Widget for which help is requested.
XtPointer call_data
'\0' terminated string holdind the URL for the helpfile.
XtPointer client_data
is not used.

For example, you can have a help-pushbutton (Widget help_button). To use the help-file "app-help.html" when the pushbutton is presses you would write (if you are using C):

XtAddCallback (help_button, XmNactivateCallback, 
	       (XtCallbackProc) get_help, 
	       (XtPointer) "app-help.html");

Of course, there are some limitations on libhelp URLs (Uniform Resource Locators).

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Libhelp version 1.8.1 (Jun 28. 95).
Thomas Harrer