Inside Macintosh: QuickTime Components /

Chapter 4 - Image Compressor Components / Image Compressor Components Reference

Image Compression Manager Utility Functions /

GetImageDescriptionExtension

Your component may use the GetImageDescriptionExtension function to obtain the extended data for an image.

pascal OSErr GetImageDescriptionExtension
                                     (ImageDescriptionHandle desc, 
                                       Handle *extension, 
                                       long idType, long index);

desc

Contains a handle to the appropriate image description structure.

extension

Contains a pointer to a field to receive a handle to the returned data. The GetImageDescriptionExtension function returns the extended data for the image described by the image description referred to by the desc parameter. The function correctly sizes the handle for the data it returns.

idType

Specifies the extension's type value. Use this parameter to determine the data type of the extension. This parameter contains a four-character code, similar to an OSType field value.

index

Specifies the extension's index value.

DESCRIPTION

The Image Compression Manager appends the extended data for an image to the appropriate image description structure (see the chapter "Image Compression Manager" in Inside Macintosh: QuickTime for information about image description structures). Note that each compressor type may have its own format for the extended data that is stored with an image. The extended data is similar in concept to the user data that applications can associate with QuickTime movies--see the chapter "Movie Toolbox" in Inside Macintosh: QuickTime for more information about user data in QuickTime movies. Once you have added extended data to an image, you cannot delete it.

RESULT CODES

noErr	0	No error
paramErr	-50	Invalid parameter specified
memFullErr	-108	Not enough memory available
noCodecErr	-8961	The Image Compression Manager could not find the specified compressor
codecExtensionNotFoundErr	-8971	Requested extension is not in the image description

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