Adobe Flash CS4 Professional for Windows and Macintosh: Visual QuickStart Guide

Basic Interactivity

463

Using Buttons to Control Timelines

Using Buttons to

Control Timelines

Most Flash creations employ a mixture of

interface objects: button symbols, button

components, and movie clips. You can script

a button (or button component) to start and

stop the playback of a movie clip, or make

the playhead jump to a speci c frame in a

movie clip.  e key is to specify the correct

target path.

The Mystery of Target Paths

All Flash creations have a certain amount of structural complexity. Even a simple movie like

the one created with ButtonActionsMaster has a hierarchy of nested objects. ( e Timeline

you see when you open a Flash document in the authoring environment is actually a movie-

clip object, so any objects on this main Timeline are considered nested objects.) But the

structure gets really complex when you nest interactive objects inside other interactive

objects—a button inside a movie clip, a movie clip inside a movie clip, a button inside a movie

clip inside a movie clip, and so on.

A nested object is known as a child object, and the object containing that child is known as

the parent object. As long as each parent and child has an instance name, it doesn’t matter

how complex the family relationship gets. You can create a script that manipulates any of the

nested objects.  e key is to identify the target object’s place in the hierarchy of Timelines

using a target path.

 ere are two types of target paths: relative and absolute. A relative target path starts with the

target object and describes its relationship to other Timelines in the hierarchy—indicating,

for example, that the target is me, or it’s one level above me; or it’s within me, one level down.

An absolute target path starts with the highest-level Timeline and works its way down the

hierarchy until it reaches the target object.

Just to complicate things, however, ActionScript 3.0 introduces a new type of interactive

object, the sprite. A sprite is similar to a movie clip, but it has no Timeline and no frames.

All of the animation and interactivity of a sprite happens because of scripting. Sprites can

also be nested and have hierarchical relationships. And you use target paths to identify them.

When you write target paths, you need to distinguish between sprite objects and Timeline-

based objects (movie clips) by using the code

as sprite

or

as movieClip

—as shown in the

examples below. (In this book, we work only with Timeline-based objects.)

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