Important: The information in this document is obsolete and should not be used for new development.
The Desktop Parameter Block
The desktop database functions use the desktop parameter block, a data structure of typeDTPBRec
:
TYPE DTPBRec = RECORD qLink: QElemPtr; {next queue entry} qType: Integer; {queue type} ioTrap: Integer; {routine trap} ioCmdAddr: Ptr; {routine address} ioCompletion: ProcPtr; {completion routine} ioResult: OSErr; {result code} ioNamePtr: StringPtr; {file, directory, or } { volume name} ioVRefNum: Integer; {volume reference number} ioDTRefNum: Integer; {desktop database reference } { number} ioIndex: Integer; {index into icon list} ioTagInfo: LongInt; {tag information} ioDTBuffer: Ptr; {data buffer} ioDTReqCount: LongInt; {requested length of data} ioDTActCount: LongInt; {actual length of data} filler1: SignedByte; {unused} ioIconType: SignedByte; {icon type} filler2: Integer; {unused} ioDirID: LongInt; {parent directory ID} ioFileCreator: OSType; {file creator} ioFileType: OSType; {file type} ioFiller3: LongInt; {unused} ioDTLgLen: LongInt; {logical length of desktop } { database} ioDTPyLen: LongInt; {physical length of desktop } { database} ioFiller4: {unused} ARRAY[1..14] OF Integer; ioAPPLParID: LongInt {parent directory ID of } { application} END; DTPBPtr = ^DTPBRec; {pointer to desktop } { parameter block}For a description of the standard fields of a parameter block (qLink
,qType
,ioTrap
,ioCmdAddr
,ioCompletion
, andioResult
), see the chapter "File Manager" in Inside Macintosh: Files. For other fields of the desktop parameter block, see the relevant routine description provided in the next section.