For Distro Packagers

blueprint-compiler is a build tool that converts UI definitions written in Blueprint into XML files that are installed with the app and that GTK can read. So for most applications that use blueprint-compiler, it is a build dependency. It is a Python program, but like most GNOME-related projects, it uses Meson as its build system.

GObject Introspection

Blueprint files can import GObject Introspection namespaces like this:

using Gtk 4.0;
using Adw 1;

To compile a blueprint file, .typelib files for all of the imported namespaces must be installed. All blueprint files must import Gtk 4.0, so Gtk-4.0.typelib is effectively a runtime dependency of blueprint-compiler. blueprint-compiler also depends on pygobject, because it uses GIRepository to determine the search path for typelib files.

So, if a package uses blueprint-compiler, its build dependencies should include the typelib files for any namespaces imported in its blueprint files. (Note that many apps also have the same typelib files as runtime dependencies, separately from blueprint).

In addition, the blueprint language server uses .gir files to provide documentation on hover. Some distros package these files separately from the main package (e.g. in a -devel package). The language server will not crash if these files are not present, but for a good user experience you should make sure they are installed.