Inside Macintosh: QuickDraw GX Printing Extensions and Drivers /

Chapter 4 - Printing Messages / Printing Messages Reference

Printing Messages

This section describes the messages that you can override to develop a printing extension or printer driver. This section presents these messages in categories that relate to the tasks for which you use each message.

Included with each message description is a list of specific result codes returned by QuickDraw GX's default implementation of the message. In addition to these result codes, you may also receive file-system, memory, and resource errors. For a complete listing of these errors, see Inside Macintosh: C Summary or Inside Macintosh: Pascal Summary.

A number of the printing messages can return communications result codes, which are listed in Table 4-2. The result codes section for each of these messages refers to this table.

Table 4-2 Communications errors returned by many of the printing messages

Result code	Explanation
gxAioTimeout	The operation timed out
gxAioBdRqstState	Asynchronous communications are in an unexpected state for the operation
gxAioBadConn	The I/O connection reference number is not valid
gxAIOInvalidXfer	Bad values were discovered in the data transfer structure
gxAioNoRqstBlks	No request blocks are available to process the request
gxAioNoDataXfer	There is no pointer to a data transfer structure specified
gxAioTooManyAutos	Automatic status request is already active
gxAioNoAutoStat	The connection is not configured for automatic status request
gxAioBadRqstID	The I/O request identifier is not valid
gxAioCantKill	The communications protocol does not support I/O termination
gxAioAlreadyExists	The protocol-specific data was already specified
gxAioCantFind	The protocol-specific data was not found
gxAioDeviceDisconn	The printer was disconnected from the computer
gxAioNotImplemented	The specified function is not implemented
gxAioOpenPending	There is already a connection opened
gxAioNoProcotolData	There was not any protocol-specific data specified in the request
gxAioRqstKilled	The I/O request was terminated
gxBadBaudRate	The specified baud rate is not valid
gxBadParity	The specified parity value is not valid
gxBadStopBits	The specified stop-bits value is not valid
gxBadDataBits	The specified data-bits value is not valid
gxBadPrinterName	The specified printer name is not valid
gxAioBadMsgType	The message type specified in the data transfer structure is not valid
gxAioCantFindDevice	The target device could not be located
gxAioOutOfSeq	A non-atomic SCSI request was submitted in the wrong order

You must define each of your message overrides with the interface that is shown in each message description. Each override must match the formal declaration of the message that it is overriding: it must take the same parameters, in the same order, as shown in
the example. You can provide your own name (whatever name you like) for each override that you define.

For clarity, Apple printing extensions and printer drivers apply the same prefix to each override they include. For example, the Apple Personal LaserWriter SC printer driver provides overrides named SD_ShutDown, SD_DefaultPrinter, SD_DespoolPage, and so on. The background picture printing extension includes overrides named BWInitialize, BWShutdown, and BWDespoolPage. You can choose to follow a similar convention for naming your message override functions. For example, you could name your override of the GXCountPages messages MyCountPages.

Most of the message descriptions also include a "Special Considerations" section, which describes whether you can send the message yourself and whether you can totally override the message. For messages that you can partially override, this section includes information about whether to forward the message prior to or after performing your own tasks.

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Subtopics

Storage Messages

Print Object Messages

Application Messages

Paper-Handling Messages

Color Profile Messages

Spooling Messages

Despooling Messages

Dialog Box Messages

Universal Imaging Messages

Raster Imaging Messages

PostScript Imaging Messages

Vector Imaging Messages

Device Communications Messages

Compatibility Messages

Finder Dialog Box Messages

Finder Menu Messages

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