The lowest level one is called Xlib. This provides a simple way for a
client program to create a window, show it (map) onto the
screen, and put various graphical things (including text) in the
window. This is illustrated in #fnxlib#1672>.
[Inside the Xlib is all the stuff to implement these simple functions,
and to turn the parameters into messages that are sent (using the X
Protocol) to the right display server].
The next library is called the X Toolkit (it is made of two parts:-
the intrinsics and the Athena widgets libraries).
There are several other Toolkit Libraries - the main contenders
for standards (i.e. ones you will find on lots of makes of machine)
is MOTIF. Others are DECWidgets and HP
Widgets, which ressemble the basic Athena widgets we will look at
A C++ library which is very easy to use and very elegant is called
Interviews. This is not widely available or documented yet -
some of the staff have used it here.
Figure: Library and Protocol Layers Model of X
Nowadays, toolkits are emerging at ever higher levels. The latest fad
is for the one associated with the tool language, Tcl, called Tk.