Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Sequence Grabber Component Functions / Working With Channel Characteristics

SGSetChannelMatrix

The SGSetChannelMatrix function allows you to set a channel's display transformation matrix.

pascal ComponentResult SGSetChannelMatrix (SGChannel c, 
                                          const MatrixRecord *m);

c

Identifies the channel for this operation. You provide your
connection identifier. You connect to a channel component by calling the SGNewChannel or SGNewChannelFromComponent function, discussed on page 5-29 and page 5-30, respectively.

m

Contains a pointer to a matrix structure, as defined by the Movie Toolbox (see the chapter "Movie Toolbox" in Inside Macintosh: QuickTime for more information about matrix structures). Set this parameter to nil to select the identity matrix.

DESCRIPTION

The SGSetChannelMatrix function allows you to specify a display transformation matrix for a video channel. The channel uses this matrix to transform its video image into the destination window. If the channel cannot accommodate your matrix, it returns an appropriate result code. Note that you may not call this function when you are recording.

Other channel component functions may affect this matrix. The SGSetChannelBounds function sets the matrix values so that the matrix maps the channel's output to the channel's boundary rectangle (this function is discussed beginning on page 5-62). The SGSetVideoRect function modifies the matrix so that the specified video rectangle appears in the existing destination rectangle (see page 5-75 for more information about this function).

RESULT CODES

matrixErr	-2203	Invalid matrix
deviceCantMeetRequest	-9408	Device cannot support grabber

SEE ALSO

You may retrieve a channel's matrix by calling the SGGetChannelMatrix function, which is discussed next.

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