This weekend, while cruising freshmeat.net, I happened upon libinklevel, from Markus Heinz. From the description:

Libinklevel is a library for checking the ink level of your printer on a system which runs Linux. It supports printers attached via parallel port or usb.

I downloaded and installed the latest versions of that and a complementary command-line tool called ink (uses libinklevel and is from the same author). No luck with my Canon i950 printer:

marc@tbird:~/sw/libinklevel-0.7.2$ sudo ink -p usb
ink v0.4.1 © 2007 Markus Heinz

Printer not supported.
Could not get ink level.

After a few minutes of glancing at the code, I was able to get it working. Here’s the patch. Now the output of the ink tool looks like this:

marc@tbird:~/sw/libinklevel-0.7.2$ sudo ink -p usb
ink v0.4.1 © 2007 Markus Heinz

Canon i950

Cyan:                          40%
Light Cyan:                   100%
Black:                         10%
Yellow:                        70%
Magenta:                       10%
Light Magenta:                100%

While I was modifying the code, I noticed that there was a #define constant called MAX\_NUMBER\_OF\_MODELS, that needed to be updated whenever one adds or removes printers to the existingPrinters array. This was a little cumbersome, so I modified the code to not need that. Here’s the patch.

I will of course send these patches to the author, Markus Heinz, so that the Canon i950 can work “out of the box” with the next version of libinklevel.