Flex 3 Anatomy

Skinning in Flex 3.

UIComponent is the core class in Flex 3 for all of the interactive classes. Its class hierarchy is UIComponent < FlexSprite < Sprite < DisplayObjectContainer < InteractiveObject < DisplayObject. A UIComponent can render graphics using the drawing API (from Sprite), have other DisplayObjects as children (from DisplayObjectContainer) and supports mouse and keyboard interaction (from InteractiveObject). But the real work in UIComponent is in basic Flex functionality it implements.

UIComponent defines the core interaction of the Flex 3 component model such as styles, tooltips, validators, states, repeaters, invalidation, measuring, layout, and rendering. The Flash classes such as Sprite do not follow these standards and are not constrained and supported by the Flex component model. This is an important consideration when choosing a base class for custom components.

Anatomy of the Flex 3 Framework.

Understanding the Flex 3 class hierarchy is the first step to grasping the Flex source code. Much of the Flex code is shared in key parent classes and it is important to understand this structure before delving into the details of a particular class in the framework.

The Flex SDK is a large body of code that Adobe has released under an open source license. Reading the Flex source code is one of the best habits to develop as a Flex developer. The code provides insight into what Adobe engineers were thinking during development and how they expect their components to be used. The code is also intended as a blueprint for implementing your own components.