[cups] Trying to work around Canon MF743cdw driver bugs on MacOS Catalina

[Helge Blischke]

> Am 16.05.2020 um 10:52 schrieb Brian Demsky <bdemsky at gmail.com>:
> 
> I found an interesting potential direction.  If I hack PPD file to just dump the raw pdf to the printer, it prints correctly.  So I guess the Canon printer actually supports pdf natively despite that this is not an advertised feature.
> 
> The only issue is that it looks like all the options are controlled by the Canon cgpdftopdl file.  In particular, I would like to have the option to print in black and white instead of color.  Any suggestions?
> 
> Brian

There are two variants to modify the PPD:

(1)	bypass the capdftopdl filter completely: 
	change the line
	*cupsFilter: "application/pdf 0 /Library/Printers/Canon/CUPS_Printer/Bins/capdftopdl“
	to
	*cupsFilter: „application/vnd.cups-pdf 0 -“
	and delete the lines starting with 
	*cupsFilter2:

	But this modification causes all PPD related option settings short of PageSize and Resolution to act as a no-op, but should prevent the empty character boxes,
	as the input PDF will be processed by Apple’s cgpdftopdf filter first.

(2)	apply both the cgpdftopdf and capdftopdl filters to the input PDF:
	change the line
	*cupsFilter: "application/pdf 0 /Library/Printers/Canon/CUPS_Printer/Bins/capdftopdl“
	to
	*cupsFilter: „application/vnd.cups-pdf 0 /Library/Printers/Canon/CUPS_Printer/Bins/capdftopdl“
	and delete the lines starting with
	*cupsFilter2:

	This modification needs to be tested; my proposal is based on the fact that my fake-printer output didn’t exhibit rendering issues on the computer display,
	but that dies not guarantee that it works with the real printer.

(3)	you could try to change the line
	*DefaultCNGraphicsMode: VectorMode
	to
	*DefaultCNGraphicsMode: ImageMode

	Alternatively,, this is easily done by the lpadmin or lpoptions utility of ba the CUPS web interface (provided it is enabled).
	The ImageMode will (hopefully) convert the input to a raster file and print that.

I’d start trying with variant 3 first.

Helge