About the CustomWriter GX and LaserWriterIIsc printer drivers…
CustomWriter GX is a QuickDraw GX printer driver that implements both custom communications code and custom buffering code. The LaserWriter IIsc printer driver demonstrates how to write a QuickDraw GX printer driver that supports SCSI, which is also a form of custom communications. This sample code is a companion to the Print Hints column in issue #21 of develop magazine, which covers custom I/O and custom buffering in depth.
The CustomWriter GX printer driver creates 32-bit deep, 72 dpi PICT files for each page of a document it "prints." These files can be viewed with SimpleText or a graphics program. Because the PICTs consists of 32-bit deep pixmaps, each file will be roughly 1.2 megabytes. You probably don't want to print any Tolstoy novels with this driver.
The main purpose of both drivers is, of course, to demonstrate how to write a printer driver which uses custom communications or buffering code. The CustomWriter GX printer driver also demonstrates how to support global data in a printer driver without using the standard methods supplied by QuickDraw GX. Most QuickDraw GX global data routines only work if called from within message overrides, but the approach used in the CustomWriter GX driver will work regardless of whether the calling code is in a message override or something like a callback routine. (This is especially useful if you're implementing total overrides of the old API compatibility dialogs--not something that this printer driver does.) Since I've received quite a few questions about how to implement this sort of global data, I've included an example of it in the CustomWriter GX driver.
