ACTIONSCRIPT 3 Developer’s Guide en

ACTIONSCRIPT 3.0 DEVELOPER’S GUIDE
Working with movie clips
Working with MovieClip objects
Flash Player 9 and later, Adobe AIR 1.0 and later
When you publish a SWF file, Flash converts all movie clip symbol instances on the Stage to MovieClip objects. You
can make a movie clip symbol available to ActionScript by giving it an instance name in the Instance Name field of the
Property inspector. When the SWF file is created, Flash generates the code that creates the MovieClip instance on the
Stage and declares a variable using the instance name. If you have named movie clips that are nested inside other named
movie clips, those child movie clips are treated like properties of the parent movie clip—you can access the child movie
clip using dot syntax. For example, if a movie clip with the instance name childClip is nested within another clip with
the instance name parentClip, you can make the child clip’s timeline animation play by calling this code:
parentClip.childClip.play();
Note: : Children instances placed on the Stage in the Flash authoring tool cannot be accessed by code from within the
constructor of a parent instance since they have not been created at that point in code execution. Before accessing the
child, the parent must instead either create the child instance by code or delay access to a callback function that listens
for the child to dispatch its Event.ADDED_TO_STAGE event.
While some legacy methods and properties of the ActionScript 2.0 MovieClip class remain the same, others have
changed. All properties prefixed with an underscore have been renamed. For example, _width and _height
properties are now accessed as width and height, while _xscale and _yscale are now accessed as scaleX and
scaleY. For a complete list of the properties and methods of the MovieClip class, consult the ActionScript 3.0
Reference for the Adobe Flash Platform .
Controlling movie clip playback
Flash Player 9 and later, Adobe AIR 1.0 and later
Flash uses the metaphor of a timeline to convey animation or a change in state. Any visual element that employs a
timeline must be either a MovieClip object or extend from the MovieClip class. While ActionScript can direct any
movie clip to stop, play, or go to another point on the timeline, it cannot be used to dynamically create a timeline or
add content at specific frames; this is only possible using the Flash authoring tool.
When a MovieClip is playing, it progresses along its timeline at a speed dictated by the frame rate of the SWF file.
Alternatively, you can override this setting by setting the Stage.frameRate property in ActionScript.
Playing movie clips and stopping playback
Flash Player 9 and later, Adobe AIR 1.0 and later
The play() and stop() methods allow basic control of a movie clip across its timeline. For example, suppose you have
a movie clip symbol on the Stage which contains an animation of a bicycle moving across the screen, with its instance
name set to bicycle. If the following code is attached to a keyframe on the main timeline,
bicycle.stop();
the bicycle will not move (its animation will not play). The bicycle’s movement could start through some other user
interaction. For example, if you had a button named startButton, the following code on a keyframe on the main
timeline would make it so that clicking the button causes the animation to play:
Last updated 6/6/2012
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