Inside Macintosh: QuickTime Components
This section describes the external interface that image compressor components must support. It also discusses the utility functions that the Image Compression Manager provides for use by compressors and decompressors.
This discussion has been divided into two parts. They discuss the image compressor component functions that are called by the Image Compression Manager. "Direct Functions" deals with image compressor component functions that are called by the Image Compression Manager in response to application requests. "Indirect Functions" discusses image compressor component functions that may be called by the Image Compression Manager at any time. The next section, "Image Compression Manager Utility Functions," defines a number of Image Compression Manager utility functions that are available to image compressor components.
Apple has defined a functional interface for image compressor components. For information about the functions your component must support, see the individual function descriptions that follow.
You can use the following constants to refer to the request codes for each of the functions that your component must support.
#define codecGetCodecInfo 0x00 /* CDGetCodecInf */
#define codecGetCompressionTime 0x01 /* CDGetCompressionTime */
#define codecGetMaxCompressionSize 0x02 /* CDGetMaxCompressionSize */
#define codecPreCompress 0x03 /* CDPreCompress */
#define codecBandCompress 0x04 /* CDBandCompress */
#define codecPreDecompress 0x05 /* CDPreDeCompress */
#define codecBandDecompress 0x06 /* CDBandDeCompress */
#define codecCDSequenceBusy 0x07 /* CDSequenceBusy */
#define codecGetCompressedImageSize 0x08 /* CDGetCompressedImageSize */
#define codecGetSimilarity 0x09 /* CDGetSimilarity */
#define codecTrimImage 0x0A /* CDTrimImage */
Code selectors 0 through 127 are reserved for use by Apple. Code selectors 128 through 191 are subtype specific. Code selectors 192 through 255 are vendor specific. Code selectors 256 through 32767 are available for general use. Negative selectors are reserved by the Component Manager.