Clarence Verge wrote:
>Now comes the chance for you to explain why four layers seem to be
>involved in the graphical system and what is responsible for what. <G>
This is how I see the things and someone correct me if I am wrong:
The X server actions can be roughly explained by the following.
X makes available to the application software rectangular portions of
screen which the program can use to do almost anything; X offers an
interface between the hardware and the higher level software. There is
absolutely no connection between X and SVGA lib. X provides means to
write, draw, change colours, and accomplishes all sorts of primitive
graphic routines. It also receives standard events like mouse clicks and
key presses and transmit them to the application software.
The widget libraries implement a collection of standard objects like
buttons, frames, textareas, listboxes, scrollbars, standard dialog
windows, menus, all based on X. There are a lot of widget libraries
around starting with the old Athena type (see xedit, xdvi),continuing
with Motif type (openmotif, lesstif) and so on. Nowadays many people
tend to use GTK and QT (see further).
Window managers do nothing but offer a way to easily manipulate the
application main windows on the screen (otherwise they would stick with
the root window, making impossible to move or resize them). They
complete an application main windows with borders, titlebars, standard
buttons for window operation and so on. They offer a convenien way to
move or resize a window using the mouse. Their action is limited
however to the application main window or dialog windows. The window
manager developers usually write programs for easier managing of the
user applications like equivalents of Windows taskbars and start menus.
Desktop managers are a conglomerate of applications and libraries. They
tend to set some kind of standards. They offer a widget library, a
window manager, some sort of other libraries which offer various
solutions i.e. for multimedia issues, and a pack of programs including
file managers, browsers, games, editors, word processors, media players
and so on. Also they offer ways of managing your desktop appearance and
some other bells and whistles which bring them very close to a well
known GUI based OS from Redmond :-). Most populars are Gnome (based
on GTK widget library) and KDE (based on QT widget library).
Cristian Burneci
Bucharest, Romania
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