This is the fourth post in a series of reports on the progress of GTK 4 Rust Bindings. You can find project links and repositories on the about page.

Since the last post, the progress has been focused on adding in more objects to all of the gtk4 family. We’re also working to integrate gtk4 into the existing gtk-rs ecosystem, starting from gir-files, the root dependency of all crates.

Upstreaming builder signals

Although the pull request is still under review, once it’s merged, we will be able to designate signal handlers in the builder file with Builder::connect_signals(). Unlike the GModule magic often used in C, the Rust version asks you to provide a callback to map each handler name to the handler to avoid breaking safety guarantees. We also plan to add an example similar to this to demonstrate its use.

Additions in gdk4-rs

The following are implemented:

DrawContext::get_frame_region()
pango_layout_get_clip_region()
pango_layout_line_get_clip_region()
Surface::create_similar_surface()
Surface::set_opaque_region()

cairo::Region is added to gdk4.

GDK events in gdk4 have been made into opaque types. I’m working on a simple typing system for them, similar to the one created for RenderNode in gsk4-rs.

Integration with gtk-rs

The ultimate goal of this project is, of course, to integrate all the work back into the gtk-rs ecosystem. The relevant gir files from gtk 3.96 (gtk4 development version) have been merged in #39. The next step is to merge sys crates (low-level API) in #145, and eventually upstream all the crates.