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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 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.

The QTPlgMediaSprite class is part of the Sprite Framework and defines a that describes sprites sample data. This class implements properties and methods that allows you to deal with characteristics peculiar to sprite samples.







The QTPlgMediaSprite class constructors are called when you create a new instance of the class, while the ˜QTPlgMediaSprite 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 QTPlgMediaSprite 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 QTPlgMediaSprite)
This is the copy constructor. The properties of the object to be copied will be used to initialize the new class instance properties

specifies the number of images that currently exist in a sprite track. The value of this property reflects the number of images that currently exist based on the key frame that is in effect
specifies the desired bit depth of the offscreen graphics world where the sprite data is drawn before it is copied to the screen. The default value is 0 (which means to use the bit depth of the deepest monitor that intersects the onscreen sprite window). Setting this property can save memory if your sprite graphics are drawn at a lower bit depth than the user’s monitor
indicates the desired frequency at which the sprite media handler should send idle events to the sprite track. The default value is –1 (which means not to issue any idle events)
specifies a solid background color for the entire sprite track
indicates how the sprite media handler interprets override samples. If this property is set to true, then the sprite media handler generates the sprite data for a particular override sample by applying the changes in that override sample directly to the key frame sample, ignoring any previous override samples. (This is the default mode.) On the other hand, if this property is set to false, then the sprite media handler generates sprite data by applying the changes in a particular override sample to the data generated by applying the changes in all previous override samples to the key frame sample data. In other words, true specifies that a particular override frame contains absolute changes to key frame data, while false specifies relative changes.
specifies whether the sprites in the sprite track are rescaled whenever the sprite track is resized. The default value is false
specifies whether the sprite track contains any wired actions
specifies whether the sprite track is visible. The default value is true. It might occasionally be useful to set the sprite track to be invisible if there are other tracks in the movie and you want to allow the user to click on items in those tracks (by putting an invisible sprite track in front that intercepts those clicks)
provides detailed informations about the stored sprites sample data descriptions
provides detailed informations about the stored sprites sample data; returns a list of objects
allows to retrieve or set the properties of sprites that currently exist in a sprite track. The list of objects returned by this property reflects the number of sprites that currently exist based on the key frame that is in effect
retrieves the sprite media sample that is currently being displayed
returns the list of sprites objects constituting the sample identified by the index i. The index range from 0 to –1

(point as ) as
allows you to determine whether the user has clicked on a sprite. This method looks at each one of the sprites in a sprite track to see whether it is currently at the location specified by the point; the location must be expressed in coordinates local to the sprite track. If more than one sprite is situated at that location, then the result is set to the properties of the frontmost sprite (that is, the sprite with the lowest ). This method accepts clicks only on a non–transparent part of a sprite and checks for both sprites
returns the properties of the sprite the user has clicked if any, otherwise returns nil. Check the class property for errors
(videoTrack as , spriteImageId as integer)
allows you to notify the sprite media handler to use the video track specified by the videoTrack parameter as the source for the sprite’s image identified by the spriteImageId parameter that corresponds to the . The video track and the sprite track has to be contained into the same QuickTime movie
returns nothing. Check the class property for errors