Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Application-Defined Functions /

MyDisplayFunction

The sequence grabber component calls your display function in order to transfer a captured video image in an offscreen buffer into the destination buffer for the video channel.

Your display function must support the following interface:

pascal ComponentResult MyDisplayFunction (SGChannel c, 
                                           short bufferNum, 
                                           MatrixRecord *mp,
                                           RgnHandle clipRgn,
                                           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.

mp

Contains a pointer to a transformation matrix for the display operation. If there is no matrix for the operation, this parameter is set to nil.

clipRgn

Contains a handle to the clipping region for the destination image.
This region is defined in the destination coordinate system. Apply
the clipping region after applying the transformation matrix. If there is no clipping region, this parameter is set to nil.

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 application sets the destination buffer by calling the SGSetChannelBounds function, which is described on page 5-62.

Your display function can use the sequence grabber component's SGDisplayFrame function to support the default behavior. SGDisplayFrame is described on page 5-101.

Main | Top of Section | What's New | Apple Computer, Inc. | Find It | Feedback | Help