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Chapter 3 - Image Compression Manager / Image Compression Manager Reference

Image Compression Manager Functions / Getting Information About Compressed Data

GetCompressedImageSize

The GetCompressedImageSize function determines the size, in bytes, of a compressed image.

Most applications do not need to use this function because compressed images have a corresponding image description structure with a size field. You only need to use this function if you do not have an image description structure associated with your data--for example, when you are taking a compressed image out of a movie one frame at a time.

pascal OSErr GetCompressedImageSize (ImageDescriptionHandle desc,
                                    Ptr data, long bufferSize,
                                    DataProcRecordPtr dataProc,
                                    long *dataSize);

desc

Specifies a handle to the image description structure that defines the compressed image for the operation.

data

Points to the compressed image data. This pointer must contain a 32-bit clean address.

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.

dataProc

Points to a data-loading function structure. If the data stream is not all in memory when your program calls GetCompressedImageSize, the compressor calls a function you provide that loads more compressed data (see "Data-Loading Functions" beginning on page 3-153 for more information about data-loading functions). If you have not provided a 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.

dataSize

Contains a pointer to a field that is to receive the size, in bytes, of the compressed image.

DESCRIPTION

Your application may use the GetCompressedImageSize function when parsing a data stream that does not contain an image description structure for each frame in the sequence.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
noCodecErr	-8961	Image Compression Manager could not find the specified compressor
codecSpoolErr	-8966	Error loading or unloading data

Component Manager errors