ActionScript: The Definitive Guide

Types of Movie Clips

Not all movie clips are created equal. In fact, there are three distinct types of clips available in Flash:

• Main movies

• Regular movie clips

• Smart Clips

In addition to these three official varieties, we may define four further subcategories, based on our use of regular movie clips:

• Process clips

• Script clips

• Linked clips

• Seed clips

While these latter unofficial categories are not formal terms used in ActionScript, they provide a useful way to think about programming with movie clips. Let’s take a closer look at each movie clip type.

Main Movies

The main movie of a Flash document contains the basic timeline and Stage present in every document. The main movie is the foundation for all the content in the document, including all other movie clips. We sometimes call the main movie the main timeline, the main movie timeline, the main Stage, or simply the root.

Main movies may be manipulated in much the same way as regular movie clips, however:

• A main movie cannot be removed from a .swf file (although a .swf file, itself, may be removed from the Flash Player).

• The following movie clip methods do not work when invoked on a main movie: duplicateMovieClip( ), removeMovieClip( ), swapDepths( ).

• Event handlers cannot be attached to a main movie.

• Main movies can be referenced through the built-in, global _root and _level n properties.

Note that while each .swf file contains only one main movie, more than one .swf may reside in the Flash Player at once—we may load multiple .swf documents ...