Flash CS4 ActionScript 3.0 Tutorial
How to Assign Scale Property to Button Symbols, Movie Symbols and Text with Flash ActionScript
The scaleX and scaleY properties set the object's scale values in the x and y directions. The object scales based on its registration point. For more information about setting and moving the registration point, see topic, Setting and Moving Object Registration Point.
Movie Symbol with instance name scaleMovie_mc
Add a Movie Symbol to the stage.
Select the object and open the Properties panel (Cmd/F3 (PC-Ctrl/F3)). Type in the name scaleMovie_mc for the Instance Name.
Add a new layer called Actions.
Option double-click (PC - Alt double-click) the keyframe in the Actions layer to open the ActionScript panel.
Copy/Paste the following code to the ActionScript panel.
scaleMovie_mc.scaleX = 2;
scaleMovie_mc.scaleY = 2;
Test your movie by pressing Cmd/Return (PC - Ctrl/Enter). By setting the scaleX and scaleY values to 2, the object scales 200% in both directions.
Easing and Scaling
Scaling doesn't need to happen instantly. By adding easing to the scale, the motion becomes more believable.
Setting the Scale Center
The object's scale origin is determined by the Movie Symbol's registration point. For information on moving the registration point, see topic, Setting/Moving Object Registration Point.