GSoC 2026 Submission Report

2026-08-18T00:00:00+00:00

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“A ship in harbor is safe, but that is not what ships are built for.”</em> – Jhon A. Shedd</p> </blockquote>
Project: COSMIC Desktop Print Dialog</a></h2>
Organization: The Linux Foundation</em></h4>
Hello! This is my final report for my GSoC 2026 project: COSMIC Desktop Print Dialog. The goal of this project was to build a CPDB-based print dialog for the COSMIC Desktop Environment and integrate it with xdg-desktop-portal-cosmic</code> (PreparePrint + Print) so desktop and sandboxed apps can print through a native COSMIC UX.</p>
TLDR: My GSoC project focused on bringing native print dialog support to the COSMIC desktop environment through two interconnected efforts: modernizing the Rust CPDB client library and building a fully functional print portal for xdg-desktop-portal-cosmic. The CPDB library work is done and merged upstream</strong> into OpenPrinting/cpdb-rs</code></a> and published on crates.io as v0.1.1</code></a>, and the print dialog is feature-complete and in review</strong> on pop-os/xdg-desktop-portal-cosmic#331</code></a>. The project is complete according to the proposal, all that remains is feedback from the review cycle and the follow-up work that a newer portal API will unlock.</p>
Here is a detailed overview of my GSoC project:</p> Table of Content</h4> Background: why this project exists</a></li> Goals of the project</a></li> Part one: updating cpdb-rs</code></a></li> Part two: The COSMIC Print dialog and portal</a></li> Current state</a></li> What’s left to do</a></li> Challenges faced during the program</a></li> What I learned</a></li> Thanks</a></li> Links</a></li> </ul> Background: why this project exists</h2> To explain the goal I need to introduce three things that had to be glued together.</p> COSMIC</strong> is System76’s new desktop environment, written in Rust on top of libcosmic</code></a>, which itself builds on the iced</code></a> GUI toolkit. It is a new DE, and until this project it had no print dialog of its own. If you press Ctrl</kbd>+P</kbd> in an application on COSMIC, you get whatever dialog the application’s own toolkit provides, usually the GTK one, which looks and behaves like a different desktop.</p> XDG Desktop Portals</strong> are the standard way for applications, especially sandboxed ones, to ask the desktop to do something on their behalf like opening a file, taking a screenshot, or like in our case printing a document. The application never gets direct access to your printers, It talks D-Bus to a portal, and the desktop’s portal implementation shows the UI and does the work. xdg-desktop-portal-cosmic</code> is COSMIC’s implementation, and it had backends for screenshots, screencasting, and file choosing, but the org.freedesktop.impl.portal.Print</code> interface was missing entirely.</p> CPDB (Common Print Dialog Backends)</strong> is an OpenPrinting project that solves a long-standing duplication problem. Historically every toolkit (GTK, Qt, LibreOffice) implemented its own print dialog and its own CUPS integration. CPDB inverts that: print systems (like CUPS) each expose a backend</strong> process over D-Bus, and any dialog can be a frontend</strong> that discovers all the installed backends and talks to them through one common interface. Write your dialog once and it works with every print system that ships a CPDB backend.</p> So the shape of the project was clear: make COSMIC a good CPDB frontend, and expose that frontend through the print portal.</p>

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GSoC 2026 Submission Report

Background: why this project exists</h2> To explain the goal I need to introduce three things that had to be glued together.</p>