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Given a starting value and an ending value, QuickTime is able to figure out, for any moment in the duration of the animation, what the appropriate value between those two values should be. This process is called tweening, and the track that contains the information needed to do the tweening is called a .

QuickTime provides support for either simple linear interpolations of data or more complex tweening operations and operations. For instance, the various types of path tweens allow us to derive values based on the shape of an arbitrary curve defined by a vector path. And the list tween derives values from a list of atoms in an atom container, which can result in a series of discrete steps of non–continuous values. Anyway, QTPlugin currently supports only linear interpolations of numerical or graphical data.

The QTPlugin provides the developers with the Tween Framework to add tween–based animation to their applications. The Tween Framework, which is a set of classes, handles all the tasks necessary to provide tweening by using either or auto–running .

The QTPlgMediaTween class is part of the Tween Framework and defines a that describes tween samples. This class inplements properties and methods that allows you to deal with characteristics peculiar to tween samples.







The QTPlgMediaTween class constructors are called when you create a new instance of the class, while the ˜QTPlgMediaTween class destructor, is called automatically when the class is no more in use. Also, you can invoke the class destructor by setting the instance of the class to nil. You can not create a QTPlgMediaTween object by yourself; instead, you will use class instances obtained from objects of appropriate type.

Once a new class instance is returned, it is good practice to check the class property to be sure that the new object can be used. See the validity requirements for more details.


The class provides you with the following initializer methods:
(other as QTPlgMediaTween)
This is the copy constructor. The properties of the object to be copied will be used to initialize the new class instance properties

provides informations about the stored tween samples data
provides detailed informations about the stored tween samples data; returns a list of objects
returns the list of constituting the sample identified by the index i. The index range from 0 to –1. The type of the objects contained into the list can be determined by using the Realbasic’s isA operator