GXDespoolData(IM:XP)

Inside Macintosh: QuickDraw GX Printing Extensions and Drivers /

Chapter 4 - Printing Messages / Printing Messages Reference

Printing Messages / Despooling Messages

GXDespoolData
QuickDraw GX sends the GXDespoolData message to read a stream of data from the spool file. If you perform your own spooling, you need to override the GXDespoolData message to interpret your spool file format. Your override of the GXDespoolData message must match the following formal declaration:
OSErr MyDespoolData (gxSpoolFile aSpoolFile,
                     Ptr data, long *length);
aSpoolFile
The spool file.
data
A pointer to the buffer that holds the data from the spool file.
length
On entry, the length of the buffer in bytes. On return, the actual number of bytes that were despooled.

function result
An error code. The value noErr indicates that the operation was successful.

DESCRIPTION
You can override the GXDespoolData message to decrpyt data if you encrypted data in an override of the GXSpoolData message.
The default implementation of this message reads the requested amount of data from the spool file.

SPECIAL CONSIDERATIONS
You rarely send the GXDespoolData message yourself.
If you are providing your own spooling, you need to totally override the GXDespoolData message and all of the other spooling and despooling messages.
If you are not providing your own spooling, you must forward the GXDespoolData message to allow the default implementation to read the data from the spool file. Forward this message prior to modifying the data.

RESULT CODES
gxSegmentLoadFailedErr A required code segment could not be found,
or there was not enough memory to load it.
gxPrUserAbortErr The user has canceled printing.
gxIncompletePrintFileErr The spool file is not complete.
gxCrashedPrintFileErr The spool file could not be opened.
gxInvalidPrintFileVersion The version number of the spool file is not valid.

SEE ALSO
The GXSpoolData message is described on page 4-70.

gxSegmentLoadFailedErr	A required code segment could not be found, or there was not enough memory to load it.
gxPrUserAbortErr	The user has canceled printing.
gxIncompletePrintFileErr	The spool file is not complete.
gxCrashedPrintFileErr	The spool file could not be opened.
gxInvalidPrintFileVersion	The version number of the spool file is not valid.