User Guide

160 Display Programming
Understanding the display architecture
Each application built with ActionScript 3.0 has a hierarchy of displayed objects known as the
display list. The display list contains all the visible elements in the application. Display
elements fall into one or more of the following groups:
■ The Stage
The Stage is the base container of display objects. Each application has one Stage object,
which contains all onscreen display objects. The Stage is the top-level container and is at
the top of the display list hierarchy:
Each SWF file has an associated ActionScript class, known as the main class of the SWF file.
When you embed a SWF file in an HTML page, Flash Player calls the constructor
function for that class and the instance that is created (which is always a type of display
object) is added as a child of the Stage object. The main class of a SWF file always extends
the Sprite class (for more information, see “Core display classes” on page 162).
Display Object
Container
Display Object
Display Object
Container
Display Object
Container
Instance of
the main class of
the SWF file
Stage
Stage
Display Object
Container
Display Object
Display Object