Contents
Navigation
Home User Reference Other Resources


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 sprites as actors performing on that stage.

Each sprite has 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.

QTPlugin uses sprite media samples to set/get data from Sprite Framework classes that need them (i.e. when creating ). There are two basic kinds of sprite media samples:

  1. those that define the sprite image array and set the initial properties of a frame
  2. those that animate the sprites in the track by specifying changes to the sprites’ properties
The image arrays and initial properties are stored in key frames, and the sprite property changes are stored in difference frames. When working with sprite data, the difference frames are called override frames (because the data in those frames overrides the data in the key frames).

The QTPlgSpriteOverrideSample class is part of the Sprite Framework and provides the container you have to use to add override frames to the target destination. This class does not add any new properties or methods to those defined in its but allows the insertion of objects only.







The QTPlgSpriteOverrideSample class constructors are called when you create a new instance of the class, while the ˜QTPlgSpriteOverrideSample 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. The conditions that determine if a QTPlgSpriteOverrideSample object is valid are the same as its .


The class provides you with the following initializer methods:
()
This is the default constructor. Use it to create an empty container in memory
(other as QTPlgSpriteOverrideSample)
This is the copy constructor. The properties of the object to be copied will be used to initialize the new class instance properties