Inside Macintosh: QuickTime /

Chapter 2 - Movie Toolbox / Movie Toolbox Reference

Functions That Modify Movie Properties / Working With Movie Spatial Characteristics

GetTrackMatte

The GetTrackMatte function allows your application to retrieve a copy of a track's matte. The matte defines which of the track's pixels are displayed in a movie, and it is valid for the entire duration of the movie. This function returns the matte in a pixel map structure. You may use QuickDraw functions to manipulate the returned matte. However, you should use the Movie Toolbox's DisposeMatte function (described in the next section) to dispose of the matte when you are finished with it.

pascal PixMapHandle GetTrackMatte (Track theTrack);

theTrack

Specifies the track for this operation. Your application obtains this track identifier from such Movie Toolbox functions as NewMovieTrack and GetMovieTrack (described on page 2-136 and page 2-188, respectively).

DESCRIPTION

The GetTrackMatte function returns a handle to the matte. Your application must dispose of this handle when you are done with it--you must use the DisposeMatte function, which is described in the next section, to dispose of the matte. If the function could not satisfy your request, it sets the returned handle to nil.

ERROR CODES

invalidTrack

-2009

This track is corrupted or invalid

Memory Manager errors

SEE ALSO

You can establish a track's matte by calling the SetTrackMatte function, which is described in the previous section. Listing 2-15 on page 2-62 shows how to use the SetTrackMatte and GetTrackMatte functions to create a track matte.