Basic concepts of Android UI Framework

Activity: The basic page unit, activity contains a window,window on which you can draw various view

View: The most basic UI component that represents a rectangular area on the screen;

Window: Represents the top-level windows, manages the display of the interface and responds to events; each activity creates a
Phonewindow object, which is an interface for activity and the entire view system to interact

Phonewindow class: This class inherits from the window class, while the Phonewindow class contains a Decorview object. In short, Phonewindow is a framelayout that is packaged in a certain package and provides a common set of window-handling interfaces.

Decorview: Is the rootview of the view in window, which is a subclass of Framelayout and an inner class in Phonewindow. Decor's English is decoration, that is, the meaning of "decoration", Decorview is the ordinary framelayout has been a certain modification, such as adding a generic title bar, and respond to specific key messages and so on.

Viewroot: It is not a view type, but a handler.

Its main function is as follows:

A. Distributing the received user-initiated event events to Decorview, such as keystrokes, touch screens, trackball, etc.;

B. Interacting with Windowmanagerservice to complete the drawing of the entire activity GUI

http://blog.csdn.net/woailuoisme/article/details/8957208

Basic concepts of Android UI Framework