Inside Macintosh: QuickTime Components /

Chapter 6 - Sequence Grabber Channel Components / Sequence Grabber Channel Components Reference

Functions / Configuration Functions for Video Channel Components

SGSetUseScreenBuffer

The SGSetUseScreenBuffer function allows the sequence grabber to control whether your video channel uses an offscreen buffer.

pascal ComponentResult SGSetUseScreenBuffer (SGChannel c, 
                                       Boolean useScreenBuffer);

c

Identifies the channel connection for this operation.

useScreenBuffer

Indicates whether to use an offscreen buffer. If this parameter is set to true, draw directly to the screen. If it is set to false, your channel may use an offscreen buffer. If your channel cannot work with offscreen buffers, ignore this parameter.

DESCRIPTION

By default, video channels try to draw directly to the screen. The SGSetUseScreenBuffer function allows the sequence grabber to direct your video channel to draw to an offscreen buffer. If your channel cannot draw offscreen, ignore this function. Note that this function will not be called when you are recording.

RESULT CODES

paramErr	-50	Invalid parameter value
cantDoThatInCurrentMode	-9402	Request invalid in current mode

SEE ALSO

The sequence grabber can determine whether it has allowed your channel to draw offscreen by calling your SGGetUseScreenBuffer function, which is described next.

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