X Window System

X Window System (commonly called X Window or X11 or more simply X ) is a system which manages the man-machine interaction by the screen, the mouse and the keyboard of some Ordinateur S in network. It is the system graphic open standard of interaction with the user on the UNIX (Linux, BSD, etc). Waiter X is optional on Mac OS X and it is possible to install a waiter X on the majority of the Operating systems, of which Windows. application is commonly said which it turns under X when it is conceived for the environment X Window.

Operation

X functions according to the model client/server:

  • the software waiter X turns on a machine which is equipped with a screen, a keyboard and a mouse; it receives and serves as the requests of posting, of entries of text and of displacement of mouse on a software Port,
  • a software customer X (software graphic) is connected to waiter X and its requests of postings to him by using the protocol X through the library X sends (Xlib).

X functions in IPv4 since years, but it can also function in IPv6.

This model of communication allows in particular the posting of windows and other elements of graphical interfaces, in room (software customers and waiter on the same machine) or off-set on another computer through the network (a graphic software turns on a distant machine and is posted on a station of office or portable).

Graphic posting is done by bitmap (fields of Pixel S) in opposition to Vectoriel.

Among customers X, one generally distinguishes one from them in particular: the Administrative of windows whose role is to manage posting, the selection, displacement, the redimensioning and decorations of the windows (a particular window being the root-window i.e. window-root).

Programming X

The Programmation for X Window can be done at various levels. Low of the Protocole X is that, or how the customer and the waiter exchange data. One so to speak never programs directly on the level of the protocol, but it can be used for to know it, in way for example to decode information which circulates.

The level above is that of library X or Xlib . Xlib proposes a rather direct translation of the requests of protocol X in calls of functions. It in particular makes it possible to create and to handle windows, to draw inside via a “graphic context” and to receive events (keyboard, mouse, exposure of the windows, messages inter-customers, etc) For Xlib, a window is a rectangle in which one can draw, and that one can raise or drop compared to the others (one can also imbricate windows); the decoration of the windows moreover high level is brought by the Gestionnaire of windows. The direct programming in Xlib is hardly adapted but for environments to the very limited graphic Environnement or for the development of toolkit .

Level following is that of X Toolkit , Xt in summary, system directed objects (but entirely in C) which makes it possible to handle widgets , which are windows provided with resources and methods, enabling them to react “all alone” to certain events. This level is composed of two parts: the X toolkit intrinsics and a play of widgets. The intrinsics are the framework in which one can communicate with the widgets and propose some widgets completely rudimentary (of which the widget Core , a window which does not react to nothing). There are several plays of widgets available for X toolkit. The play Athena (Xaw in summary), developed with the MIT, is small and not very complete, but it with the advantage of being light, standard and free. Two other important examples are the play Motif of OSF, very commun run for the commercial applications until about 2000, and OpenLook, which imitates the appearance of SunView, of which he is the substitute.

These various libraries are less and less used, with the profit of others surcouches of Xlib, which fulfill the same functions as Xt but which are disjoined of him. The two principal ones are GTK+ and Qt.

Extra informations

Software customers X undoubtedly more known and that which is used for also testing a good parameter setting are xclock ( Xeyes and xlogo also is very much used at ends of demonstration).

It is the MIT which published the first version of X Window System in June 1984.

At the end of the Years 1980, Sun proposed a protocol and a programmable waiter moreover high level NeWS - programmable in a language extending PostScript for the distant graph, which did not have discounted success.

The protocol Virtual Network Computing (VNC), which is not related to X and has customers and waiters on many platforms, makes it possible to remotely post a screen by a protocol of very low level.

See too

External bonds

  • X.org, site of X.Org Foundation
  • Elements of programming with X11
  • the point on the graphic treatment under Linux (August 30th, 2005)

Simple: X Window System

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