Clipping(IM: QC)

Inside Macintosh: QuickTime Components /

Chapter 8 - Video Digitizer Components / Video Digitizer Components Reference

Clipping
Some video digitizer components can clip the output video image based on an arbitrary clipping region. Your application can determine whether a video digitizer component supports clipping by examining the digitizer information structure of the component. Specifically, if the digiOutDoesMask flag is set to 1 in the outputCapabilityFlags field of the appropriate digitizer information structure, the component supports clipping. See "The Digitizer Information Structure" beginning on page 8-20 for details. Your application can obtain a component's digitizer information structure by calling the VDGetDigitizerInfo function, which is described on page 8-24. This section describes the functions provided to applications by components that support clipping.
Applications can use the VDSetClipState and VDGetClipState functions to enable and disable clipping, and to determine whether clipping is enabled. Applications can use the VDSetClipRgn and VDClearClipRgn functions to manipulate the clipping region. Applications can use these functions only during an active grab sequence. Applications set the initial clipping settings by calling either VDSetPlayThruDestination or VDSetPlayThruGlobalRect (described on page 8-35 and page 8-39, respectively).

Note
The functions that manipulate clipping and clipping state operate on a clipping region in addition to the one specified by the mask passed by the VDSetPlayThruDestination and VDSetUpBuffers functions (described on page 8-35 and page 8-54, respectively). To determine the final clipping regions, intersect these two clippings.

Subtopics

VDSetClipRgn

VDClearClipRgn

VDSetClipState

VDGetClipState