X Window Programming From Scratch笔记（1

X Window Server

    The X Window Server is responsible ofr managing all resources available to a display

##The term display in X Window vernacular does not refer noly to the monitor associated with a workstation. A display is everything having to do with input and output for a specific system.

 ##A typical display is a single monitor, keyboard, and mouse. However, it can be simply a touch-type plasma screen, or, it can consist of several monitors, a graphics tablet and a keyboard.

##Whatever the hardware configuration for your workstation, the X Server is responsible for its management.

X Server启动过程

在SYSV系列的UNIX，X Server is generally added to an initlevel.

Initlevel stands for initalization level as dfined in the system file /etc/inittab.

Under the BSD family of UNIX,an entry can be made in the /etc/rc.local file to start the server

When the system is configured to automatically run X,the command for starting the server is xdm.(xdm, manages an X display by promping for login name and password, authenticating the user, and runnng a "session".)

Executing the xdm command starts the X display Manager, which enforces te user login process.After a user has successfully entered login ID and password, xmd launches the X server.

如果系统随机启动X Server，可以运行startx或者xinit启动X。

The Flow of Events int the X Client/Server Model

X Window System是基于事件驱动的。X Server发送display hardware产生的events给X Client。Events acted on bye a client in turn generate requests of the server。因为client需要时间处理从server接收到的event，server为所有的client按队列的形式管理event.client is responsible for removing the events from the queue and processing them.

The Critical Role of the Window Manager

An X Client know as a window manager is key to any desktop environment. A window manager is a special purpose application that provides the capability of X applications to be moved,resized,minimized,and restored dynamically by the user.

The window manager applies decorations to an application that enable the user to access these features.

To review, the X Server manages all display resources and relays events that occur in the hardware to the clients it serves. Further, the clients process the events and generate server requests.

Requests instruct the X Server to perform task such as creating, positioning,coloring,destroying,rendering,drawing,and clearing windows