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Chapter 5 - Sequence Grabber Components / Sequence Grabber Components Reference

Sequence Grabber Component Functions / Utility Functions for Video Channel Callback Functions

SGDisplayCompress

The SGDisplayCompress function provides the default behavior for your display-compress function.

pascal ComponentResult SGDisplayCompress (SGChannel c, 
                                    Ptr dataPtr, 
                                    ImageDescriptionHandle desc, 
                                    MatrixRecord *mp, 
                                    RgnHandle clipRgn);

c

Identifies the channel for this operation. The sequence grabber provides this value to your display-compress function.

dataPtr

Contains a pointer to the compressed image data. The sequence grabber provides this pointer to your display-compress function.

desc

Specifies a handle to the image description structure to use for the decompression operation. The sequence grabber provides this handle to your display-compress function.

mp

Contains a pointer to a matrix structure. This matrix structure contains the transformation matrix to use when displaying the image. If there is no matrix for the operation, set this parameter to nil.

clipRgn

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

SPECIAL CONSIDERATIONS

You should call the SGDisplayCompress function only from your display-compress function. If you call it at other times, results are unpredictable.

RESULT CODE

cantDoThatInCurrentMode

-9402

Request invalid in current mode

SEE ALSO

See the next section, "Application-Defined Functions," for information about display-compress functions.

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