Main prints through craft-print, which runs `lp`; a Flatpak has no `lp`,
so File › Print fails there. This keeps craft-print as the route wherever
`lp` is on the path (and on Windows) and adds two more behind it:
- `photocraft-ipp`, a pure-Rust IPP client (CUPS-Get-Printers/Classes/
Default, Print-Job over HTTP/1.1) that talks to CUPS over its socket or
TCP; the Flatpak manifests grant --socket=cups for it. A `printServer`
named in the request always takes this route. `file.print.printers`
lists the queues.
- The XDG Print portal as the app's spooler (`Session::print_spooler`),
for a sandbox without the CUPS socket or a system without a printer:
the system print dialog, seeded with copies, paper and orientation.
PHOTOCRAFT_PRINT_PORTAL=1 prefers it, =0 removes it.
A route that exists but fails (unknown printer, refused job) is an error;
only a missing route moves on. Results gain `backend` (lp, windows, ipp,
portal). docs/printing.md describes the routes.
Diego Chagas
235e7578f3