23.1. Scheduled Screen Updates

In ActionScript, screen updates are inexorably linked to the Flash runtime's animation capabilities. Even pure ActionScript applications created with Flex Builder 2 or the mxmlc command-line compiler are governed by the Flash runtime's animation-centric screen-update system.

The Flash runtime's screen-update system is designed to accommodate the Flash authoring tool's model for creating scripted animated content. In the Flash authoring tool, animated content is produced manually as a series of frames on a timeline, exactly like the frames in a physical filmstrip. Each visual frame can be associated with a block of code known as a frame script. In very general terms, when the Flash runtime plays an animation that was created in the Flash authoring tool, it adheres to the following screen-update cycle: