Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Application-Defined Functions /

MyGrabFunction

The sequence grabber component calls your grab function in order to start capturing a frame of video data.

Your grab function must present the following interface:

pascal ComponentResult MyGrabFunction (SGChannel c, 
                                       short bufferNum, 
                                       long refCon);

c

Specifies the reference that identifies the channel for this operation.

bufferNum

Identifies the buffer for this operation. You can obtain information about this buffer by calling the SGGetBufferInfo function, which is described on page 5-98.

refCon

Contains a reference constant value. You can set this value by calling the SGSetChannelRefCon function, which is described on page 5-64.

RESULT CODE

cantDoThatInCurrentMode

-9402

Request invalid in current mode

SEE ALSO

Your grab function can use the sequence grabber component's SGGrabFrame function to support the default behavior. SGGrabFrame is described on page 5-99.