Movie clips are a crucial component of many Flash projects, particularly those containing any amount of ActionScript. Regardless of the type of project, you will use a lot of movie clips, so it is instructive to have a thorough understanding of these important Flash components.
For our purposes, think of movie clips as objects with properties that can be changed.
For example, later in this series, I will review a script that controls the location of a volume slider along a specified vertical axis. You will also control a video slider along a horizontal axis. Both sliders must be converted to movie clips before the scripting is applied to manipulate the location properties (one is the H-location; the other is the V-location) of each clip.
Scripts can also be written to control the color, shape, opacity and other graphic properties of movie clips
Another necessary key understanding is that movie clips contain their own Timelines that are independent of all other Timelines in a Flash project. Not only can a movie clip Timeline start, stop, and skip to other frames independently of other running Timelines, but these Timelines also can be controlled entirely with ActionScript. In other words, movie clips can be started, stopped, or even deleted entirely on the fly.
Also, a movie clip can be "nested" inside another movie clip. These clips are referred to as a "child" of the "parent" movie clip. Relationships between nested movie clips are hierarchical: modifications made to the parent will affect the child. One useful technique is to use ActionScript to send messages between movie clips and their Timelines. To control a movie clip Timeline from another Timeline, you must specify the location of the movie clip with a target path. A target path is just a set of directions, written in a particular way, that tells Flash where to find the various nested movie clip Timelines. I will go into more detail about target paths in a later article.
The Flash Movie Explorer and the Scene Selector breadcrumb (see Figure 5) above the Timeline are very handy tools for viewing the hierarchy of nested movie clips in a document.
Figure 5 The Scene Selector breadcrumb above the Timeline is a very handy tool, especially if you are working with several levels of nested movie clips.