Inside Macintosh: QuickTime Components /

Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Sequence Grabber Component Functions / Controlling Sequence Grabber Components

SGUpdate

The SGUpdate function allows you to tell the sequence grabber that it must refresh its display.

pascal ComponentResult SGUpdate (SeqGrabComponent s,
                                  RgnHandle updateRgn);

s

Specifies the component instance that identifies your connection to the sequence grabber component. You obtain this value from the Component Manager's OpenDefaultComponent or OpenComponent function.

updateRgn

Indicates the part of the window that has been changed. You may use this parameter to specify a portion of the window that you know has been changed. You can obtain this information by examining the appropriate window record. For example:

   SGUpdate (theSG, ((WindowPeek)updateWindow)->updateRgn);

If you set this parameter to nil, the sequence grabber uses the window's current visible region.

DESCRIPTION

You may use the SGUpdate function to tell the sequence grabber that it must refresh its display. You should call this function whenever you receive an update event for a window that contains a sequence grabber display. You should call this function before calling the Window Manager's BeginUpdate function.

Your application should avoid drawing where the sequence grabber is displaying video. Doing so may cause some video digitizer components to stop displaying video.

SPECIAL CONSIDERATIONS

It is dangerous to allow an update event to occur during recording. Many digitizers capture directly to the screen; thus, an update event will result in data loss.

RESULT CODES

paramErr	-50	Component not found
deviceCantMeetRequest	-9408	Device cannot support grabber

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