Desktop Team Updates – Monday 29th May 2023

Project Discussion Desktop
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Sorry, was busy during last weeks (LAS 2023, Engineering Sprint, OpenPrinting Summit) and therefore not writing here. See my OpenPrinting May News for what happened in the last weeks. Here some highlights and post-News updates:

  • cups-filters: To finalize the 2.0.0 release, worked on first bugs which got reported by users of Ubuntu 23.04 and Fedora 38 (the first 2 distros with cups-filters 2.x, there was a cups-filters 2.x release party on the LAS 2023 in Brno):
    • All PDFs when printed come out mirror image (Ubuntu bug #2018538): Bug occured with all PPDs with “MirrorPrint” option, setting of the option (“True”/“False”) was not considered. Fixed upstream in libppd, commit a86f999
    • cups-browsed is using an excessive amount of CPU (Ubuntu bug #2018504): Bug got introduced by the addition of multi-threading support. Failed creation of a CUPS queue in a sub-thread set a global variable to stop the update loop in the main thread with some items staying untreated and to be done in the next run. By this variable not been set an infinite loop of immediately stopping update loop happened, blocking cups-browsed completely and taking high CPU load.This is fixed upstream in cups-browsed, commit cb115406
    • HP Envy 4520 Printing issues from Chrome/Chromium (libcupsfilters issue #29): The developers of the Chrome/Chromium browser made it send resolution=96dpi along with print jobs, that looks like they did not understand that this attribute is actually to select the printer’s resolution to use. This messes up printouts on raster printers. Fixed in libcupsfilters by ignoring invalid resolution values, commit 2892e9a
    • Brother DCP-J125 not printing after update to cups-filer 2.0b3 & 2.0rc1 (libppd issue #20): Turned out to have gotten introduced when converting the pstops CUPS filter into a filter function. Too many fprintf() calls to output the print data to stdout were replaced by an internal function call. This happens for all PostScript printers (and printers with proprietary drivers which require PostScript input, like for example Brother) which stack the pages face-up and therefore need to output the pages in reverse order. Not yet fixed upstream. Needs to be fixed in libppd. Update: Fixed upstream in libppd as commit 2afb353
    • PDFtoraster - Printout of image files (.JPEG, .PNG) are not properly aligned and cropped (cups-filters issue #529): Still waiting for further user input, possibly the user is still using cups-filters 1.x.
  • CUPS: Version 3.x got postponed by a year, end-2024 instead of end-2023, so we get 2.5.x in Ubuntu 24.04 LTS, but nevertheless, we get into the PPD-free, all-IPP New Architecture, with the CUPS Snap as the print environment and Printer Application Snaps as printer drivers from Ubuntu 23.10 on.
  • GitHub security bug tutorial: Discovered ho one activates private security bug reporting in GitHub, it was really well hidden. Talked with @eslerm about this and had a meeting with @eslerm, @mdeslaur, and @sarnold from the Canonical Security Team on the Engineering Sprint. I learned how to handle the reported security bugs and they how to activate the security bug feature in GitHub, result is this tutorial for all projects who use GitHub!
  • Linux Application Summit 2023 in Brno: Report with links to all videos in my May News. And a news article (mentioning me and also @hellsworth) in the German c´t computer magazine.
  • OpenPrinting Summit 2023/PWG Meeting: Annual meeting of OpenPrinting with the Printer Working Group (PWG). See the site with all the slides, about CUPS, cups-filters, Printer Applications, GSoC, IPP, …
  • GUADEC 2023 in Riga: My 2 proposals, both the talk “The New Printing GUIs: GNOME Control Center and Common Print Dialog Backends” and the workshop “Your app everywhere, just in a Snap!” got accepted! As @hellsworth is not able to attend @jssotomdz has stepped up as co-speaker for my workshop. Thanks a lot!! There is also a second CfP for more BoFs and workshops until June 12.
  • Google Summer of Code 2023: Unfortunetely, we got only 6 of the requested 10 contributor slots for our OpenPrinting projects, but the most important ones are included. They also already have started with their work.
  • OMG! Ubuntu: They have posted and article about the switch of Ubuntu 23.10 to the CUPS Snap! Answered to several comments there.
  • OpenPrinting; Monthly video meeting and May News Post.
  • Bugs.
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