26 August 2010
A tween in Adobe Flash Professional is an animation that is created by specifying a value for an object property in one keyframe and another value for that same property in another keyframe. Flash calculates the values for that property in between those two frames. The term tween comes from the words "in between."
There are several types of tweens, including classic tweens (using the older Timeline animation method), motion tweens (using the Motion Editor and motion paths), and shape tweens (the result of drawing two separate vector shapes and morphing one to another). In addition to tweening movement, you can tween filters, color effects, and transparency.
Objects that can be tweened include movie clip symbols, graphic symbols, button symbols, and text fields. The properties of these objects that can be tweened include the 2D x and y position, scale x and y, skew x and y, 3D z position (movie clips only), 2D rotation (around the z axis), and 3D x, y, and z rotation (movie clips only).
3D motion requires the FLA file to be set to use ActionScript 3 and Flash Player 10 or later in the publish settings.
A tween span is a group of frames in the Timeline located between the beginning and ending keyframes of a tween; it is displayed in a single layer with a blue background. Only one object on the Stage can be animated in each tween span. This object is called the target object of the tween span.
A property keyframe is a frame within a tween span where you explicitly define one or more property values for the tween target object.
To learn more about tweening, see Working with tween spans in the Timeline in the Flash documentation.