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Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Image Compression Manager Functions / Changing Sequence-Decompression Parameters

SetDSequenceDataProc

The SetDSequenceDataProc function lets you assign a data-loading function to the sequence.

pascal OSErr SetDSequenceDataProc (ImageSequence seqID, 
                                    DataProcRecordPtr dataProc,
                                    long bufferSize);

seqID

Contains the unique sequence identifier that was returned by the DecompressSequenceBegin function (described on page 3-107).

dataProc

Points to a data-loading function structure. If the data stream is not all in memory when your program calls DecompressSequenceFrame, the decompressor calls a function you provide that loads more compressed data (see "Data-Loading Functions" beginning on page 3-143 for more information about data-loading functions). If you have not provided a data-loading function, or if you want the decompressor to stop using your data-loading function, set this parameter to nil. In this case, the entire image must be in memory at the location specified by the data parameter to the DecompressSequenceFrame function (see page 3-110).

bufferSize

Specifies the size of the buffer to be used by the data-loading
function specified by the dataProc parameter. If you have not specified a data-loading function, set this parameter to 0.

DESCRIPTION

Data-loading functions allow decompressors to work with images that cannot fit in memory. During the decompression operation the decompressor calls the
data-loading function whenever it has exhausted its supply of compressed data.
Your data-loading function then fills the available buffer space with more compressed data. The decompressor starts using the data-loading function with the next image in the sequence. See "Spooling Compressed Data," which begins on page 3-44, for more information about data-loading functions.

There is no parameter to the DecompressSequenceBegin function that allows you to assign a data-loading function to a sequence.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified