Inside Macintosh: QuickDraw GX Printing Extensions and Drivers /

Chapter 4 - Printing Messages / Printing Messages Reference

Printing Messages / Compatibility Messages

GXPrValidate

QuickDraw GX sends the GXPrValidate message when an application that supports the Macintosh Printing Manager calls the PrValidate function. You can override the GXPrValidate message to customize the handling of the PrValidate function. Your override of the GXPrValidate message must match the following formal declaration:

OSErr MyPrValidate (THPrint aTHPrint, Boolean *aBoolean);

aTHPrint

A handle to the print record for this printing operation.

aBoolean

On return, a Boolean value that is true if the user confirmed the dialog box and false if not.

function result

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

IMPORTANT

The default implementation of this message sends a GXPrintDefault message if the value of the devKind field in the print record is other than 0xA900 or if the value of the prVersion field in the print record is other than 8.

DESCRIPTION

The default implementation of this message validates the print record using the universal print structure. It sends the GXConvertPrintRecordTo message, validates the contents of the structure, and then sends the GXConvertPrintRecordFrom message.

You can override this message if you need to add any special handling to the processing of PrValidate calls by your printer driver.

SPECIAL CONSIDERATIONS

You never send the GXPrValidate message yourself.

You only forward the GXPrValidate message so that the default implementation can perform its operations if you do not have a custom print-record format.

The customization resource is described on page 6-47 in the chapter "Printing Resources" in this book.

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.

SEE ALSO

The PrValidate function is described in Inside Macintosh: Imaging With QuickDraw.

The universal print structure is described in the section "The Universal Print Structure" on page 4-12.

The GXConvertPrintRecordTo message is described page 4-161.

The GXConvertPrintRecordFrom message is described on page 4-160.

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