Archive for the 'Software' Category

Patchutils now on GitHub

Monday, December 22nd, 2014

Patchutils now lives here. That is all.

Fewer auth dialogs for Print Settings

Wednesday, July 30th, 2014

The latest version of system-config-printer adds a new button to the main screen: Unlock. This is a GtkLockButton attached to the “all-edit” polkit permission for cups-pk-helper.

The idea is to make it work a bit more like the Printing screen in the GNOME Settings application. To make any changes you need to click Unlock first, and this fetches all the permissions you need in order to make any changes.

Screenshot from 2014-07-30 10:20:43

Network printing

Tuesday, March 4th, 2014

It’s nearly two years since I wrote about session printing, in which the user doesn’t need to modify a locally running CUPS instance in order to print to a network printer. The main advantage of having printing running entirely in the user session is that no special privileges are needed. After all, all you need to do is send the document over the network.

So what’s the current state of play?


Dual Band routers vs mDNS

Tuesday, February 11th, 2014

Wanted to write this up in case someone else is scratching their head with the same issue.

Some routers are able to use both 2.4 GHz and 5 GHz frequencies, allowing devices to appear as though they are on the same network regardless of which they use. These actually provide two different wireless networks, with different SSIDs, and bridge between the two.

This works fine for most things, but today I realised that it’s the cause of a printer problem I’d been having. The printer was using the 2.4 GHz network while my laptop was using the 5 GHz one. When I tried to print, the mDNS name of the printer was needed so a multicast query was sent… but the printer didn’t respond.

The reason is the printer never received the query. The mDNS multicast address is, which is for multicast to the local subnet only. My router interprets this to mean that packets sent on the 2.4 GHz network will not reach the 5 GHz network.

Printing to Google Cloud Print from GTK+

Friday, January 31st, 2014

I’ve been working on a Google Cloud Print GTK+ print module.

Google Cloud Print is a web service provided by Google that allows people to share their printers. In addition to being able to print to printers shared that way, there is a cloud equivalent of “Print to file” in the form of “Save to Google Drive”.

Here is a screenshot of the print dialog (from gedit) with this module included:


The cloudprint module uses gnome-online-accounts to obtain the OAuth 2.0 access token for the Google account, which is why the Google goa backend needs an additional scope.

Currently it can discover available printers, get simple details about them such as display name and status, and submit jobs without any special options. I plan to add options-setting based on the capabilities advertised by the printer.

To try it out you’ll need to patch gnome-online-accounts and gtk+.