On July 1st, the very first round of GNOME Fellowships started. This program finances contributors within the GNOME project through your donations . We, the fellows, will be giving you monthly updates about our work. This is the very first update from me.

Short Introduction

Hey, I’m Sophie. I have been working with GNOME technology for eight years. While I’m a physicist by trade, I have been programming for more than 20 years. You might have used apps like Pika Backup , Image Viewer , or Key Ring , which I developed, or used websites like apps.gnome.org or welcome.gnome.org that I created.

Among my goals for this fellowship are to get the image library glycin into the state that we can deprecate its predecessor gdk-pixbuf, establish new governance structures like an RFC process in the GNOME project, and explore better integration of Rust in the GNOME ecosystem.

Glycin

Glycin has already seen relatively fast adoption. One of the major reasons is that media processing code written in C is a major attack surface. In this year alone, five security issues have been reported against the gdk-pixbuf project. In the future, glycin-exclusive features like higher color-depth support, proper color space management, and HDR support will become even more relevant.

Gdk-pixbuf has switched to using glycin as the default backend on Linux for a while. This way, the attack surface is already largely reduced. However, not all distributions have adopted the option yet, and on other platforms like Windows and macOS libglycin hasn’t been available to begin with.

One feature missing from glycin that is supported by gdk-pixbuf has been support for reading and writing pixel densities from images. This feature is now available for JPEG, PNG, and TIFF images. I have also created a merge request to support this feature in gdk-pixbuf via the glycin backend.

I already added basic support for macOS and Windows, as well as other operating systems, to glycin before the beginning of the fellowship. To address a few remaining build issues on Windows and macOS for libglycin, I explored fixing them by switching the complete build process from cargo to meson. However, it turns out that the meson main branch is still lacking features to make this work. Instead, I landed a patch by Felix to work around the issues. There are still some issues remaining on Windows with the GCC instead of the MSVC compiler. If someone has experience with that, fixes are very welcome.

Here is a quick list of all the smaller changes that have landed in glycin over the last month:

• • OpenEXR images that use half-precision floats now use the same memory format in glycin, saving half of the memory compared to the previously used single-precision floats.
  • Support for the Radiance HDR format has been added.
  • The lcms2 C-library has been dropped in favor of moxcms, which is written in safe Rust and improves the performance for images with ICC profiles noticeably.
  • Internally, there is now a mechanism for a loader to report if ICC profiles or CICP (HDR instructions) should be preferred, since this differs between image formats.
  • There is now an option to disable the glycin sandbox by setting the environment variable GLYCIN_DISABLE_SANDBOX=i-know-the-risks . There is now also a test_disable_sandbox meson option to disable the use of sandboxes when running tests for build servers that don’t support sandboxing.
  • Glycin’s seccomp filter now uses a blocklist instead of an allowlist. This simplifies the feature a lot and should be sufficient since the seccomp filters are only a second line of defense behind guards like namespaces. It should also fix an issue with 32-bit apps, like Steam, calling 64-bit loaders.
  • When creating new images, glycin now supports automatically converting the provided texture memory format to a format supported by the targeted image format. This feature can be controlled via Creator::set_transform_memory_format . As a result, glycin is now aware of the supported memory formats for all image formats. This information is now available via ImageEditorConfig::creator_memory_formats .
  • Metadata support has been extended by also loading XMP data for GIF, TIFF, and WebP images.
  • On request of the Inkscape project, a new API to disable the automatic conversion of textures to sRGB if an ICC profile is present has been added, along with a new API to fetch ICC profiles. This gives apps optional manual control over color management.

Image Viewer (Loupe)

The Image Viewer is showing some of the new information that is available via the new glycin features.

If pixel density metadata is available, it is shown in DPI, as well as the calculated physical size of the image. One example where this is particularly useful is scanned photos where the information is automatically added.

The used color profile, either ICC profile or CICP data, will also be shown.

RFC Proposal Draft

I have posted my first draft of a proposal for an RFC process within the GNOME project. Previously the document went through several iterations with the goal of striking a balance between making the decision process robust and avoiding stalls, while also not making it too complicated and bureaucratic. The initial discussion about the proposal is now taking place. For more information on why we are working towards better governance structures, I suggest reading Emmanuele’s original post .

Support the GNOME Project

The GNOME Fellowships are funded by our community. If you would like to help the GNOME project to stay sustainable, please consider donating .