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Sprites were introducted in QuickTime 2.5 and have since been enhanced in later versions of QuickTime.

The metaphor of a sprite animation as a theatrical play is used, in which sprite tracks are characterized as the boundaries of the stage and a sprite world or a as the stage itself. To extend the metaphor, you may want to think of as actors performing on that stage.

Each has properties that describe its location and appearance at a given time. During an animation sequence, modifying the sprite’s properties causes it to change its appearance and move around the screen. Sprites may be mixed with still–image graphics to produce a wide variety of effects while using relatively little memory.

The QTPlugin provides the developers with the Sprite Framework to add sprite–based animation to their applications. The Sprite Framework, which is a set of classes, handles all the tasks necessary to compose and modify sprites, their backgrounds and properties, in addition to transferring the results to the screen or to an alternate destination.

The QTPlgSpriteMediaDesc class is part of the Sprite Framework and defines the sample description object you have to associate to the sprites when adding them to a . Also, you obtain instances of this class when inspecting the of an existing sprite track.







The QTPlgSpriteMediaDesc class constructors are called when you create a new instance of the class, while the ˜QTPlgSpriteMediaDesc 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.

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 of the for more details.


The class provides you with the following initializer methods:
()
This is the default constructor. Use this constructor to create a completely new data descriptor container in memory
(other as QTPlgSpriteMediaDesc)
This is the copy constructor. The properties of the object to be copied will be used to initialize the new class instance properties

specifies how to interpret samples associated to the sample description instance. Let this property set to 0