User Guide

Using absolute and relative target paths 23
Parent and child movie clips
When you place a movie clip instance on another movie clip’s Timeline, the placed movie clip is
the child and the other movie clip is the parent. The parent instance contains the child instance.
The root Timeline for each level is the parent of all the movie clips on its level, and because it is
the topmost Timeline, it has no parent.
A child Timeline nested inside another Timeline is affected by changes made to the parent
Timeline. For example, if
portland is a child of oregon and you change the _xscale property of
oregon, then the scale of portland also changes.
Timelines can send messages to each other with ActionScript. For example, an action on the last
frame of one movie clip can tell another movie clip to play. To use ActionScript to control a
Timeline, you must use a target path to specify the location of the Timeline. For more
information, see “Writing target paths” on page 25.
Movie clip hierarchy
The parent-child relationships of movie clips are hierarchical. To understand this hierarchy,
consider the hierarchy on a computer: the hard disk has a root directory (or folder) and
subdirectories. The root directory is analogous to the main Timeline of a Flash document: it is
the parent of everything else. The subdirectories are analogous to movie clips.
You can use the movie clip hierarchy in Flash to organize related objects. Any change you make to
a parent movie clip also affects its children.
For example, you could create a Flash document containing a car that moves across the Stage.
You can use a movie clip symbol to represent the car and set up a motion tween to move it across
the Stage.
To add wheels that rotate, you can create a movie clip for a car wheel, and create two instances of
this movie clip, named
frontWheel and backWheel. Then you can place the wheels on the car
movie clip’s Timeline—not on the main Timeline. As children of
car, frontWheel and
backWheel are affected by any changes made to car; they move with the car as it tweens across
the Stage.
To make both wheel instances spin, you can set up a motion tween that rotates the wheel symbol.
Even after you change
frontWheel and backWheel, they continue to be affected by the tween on
their parent movie clip,
car; the wheels spin, but they also move with the parent movie clip car
across the Stage.
Using absolute and relative target paths
You can use ActionScript to send messages from one Timeline to another. The Timeline that
contains the action is called the controlling Timeline, and the Timeline that receives the action is
called the target Timeline. For example, there could be an action on the last frame of one Timeline
that tells another Timeline to play. To refer to a target Timeline, you must use a target path,
which indicates the location of a movie clip in the display list.