Inside Macintosh: QuickTime Components /

Chapter 10 - Derived Media Handler Components / Derived Media Handler Components Reference

Functions / Graphics Data Management

MediaGetTrackOpaque

The MediaGetTrackOpaque function allows the Movie Toolbox to determine whether your media is transparent or opaque when displayed.

pascal ComponentResult MediaGetTrackOpaque (ComponentInstance ci,
                                        Boolean *trackIsOpaque);

ci

Identifies the Movie Toolbox's connection to your derived media handler.

trackIsOpaque

Contains a pointer to a Boolean value. Your media handler must set this Boolean value to indicate whether your media is transparent or opaque when displayed. Set the Boolean value to true if your media is semitransparent (that is, you draw in blend mode); otherwise, leave the flag unchanged.

DESCRIPTION

The Movie Toolbox uses this function when it is building a movie from composited images. Your media handler returns information that tells the toolbox whether your media's displayed image is to be combined with other images that are already on the screen. If you draw your media in blend mode, for example, your media is semitransparent, and its display relies upon other images on the screen. The Movie Toolbox needs to know this in order to correctly display the movie to the user.

Your derived media handler should support this function if your media is semitransparent when displayed or if you handle display transfer modes.

The Movie Toolbox calls this function only if you have set the handlerHasSpatial
or handlerCanTransferMode flag to 1 in the flags parameter of the MediaSetHandlerCapabilities function.

RESULT CODES

Any Component Manager result code

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