Valhalla

A minimal wallpaper application for Linux desktops, inspired by Damask, written in Rust with GTK 4 and libadwaita.

Valhalla picks wallpapers from online sources and — most importantly — always matches them to your desktop's light/dark preference, so dark mode never gets a blinding white wallpaper.

Screenshots

Features

• Theme-aware selection: wallpapers are analyzed (average brightness) and matched against the desktop color scheme; selection re-runs immediately when you switch light/dark mode
• Sources: Wallhaven and Unsplash
• Filters: tags, categories, purity (SFW/sketchy/NSFW), resolution, aspect ratio, sorting
• API keys stored in the GNOME Keyring (required for NSFW on Wallhaven and for any Unsplash usage)
• Automatic refresh on an interval, on theme change, or manually
• Runs everywhere the XDG desktop portal does (GNOME, KDE, ...), with a direct GSettings fallback on GNOME; sets picture-uri and picture-uri-dark independently so a manual theme flip never shows a mismatched wallpaper
• Headless daemon (valhalla --daemon) for refreshing without a window, with an opt-in "Start at login" switch (XDG autostart entry)

Building

Development happens in a distrobox/toolbox container (or any distro with the GNOME stack):

distrobox enter valhalla
cd ~/Projects/valhalla
cargo build --release

Requirements (Fedora, run inside the container):

sudo dnf install -y rust cargo rustfmt clippy gcc pkgconf-pkg-config \
    gtk4-devel libadwaita-devel libsecret-devel glib2-devel blueprint-compiler git

Flatpak

The app is distributed through a self-hosted Flatpak repository: every release is built automatically in CI from flatpak/io.github.tunix.valhalla.json on the GNOME 49 runtime and published (GPG-signed) to the tunix remote.

Install (recommended): add the remote once, then install like any Flathub app. Future updates arrive via flatpak update.

flatpak remote-add --if-not-exists tunix \
    https://alperkan.at/flatpak/tunix.flatpakrepo
flatpak install tunix io.github.tunix.valhalla

Or the single-command version, which adds the remote and installs in one step via the signed ref file:

flatpak install \
    https://alperkan.at/flatpak/io.github.tunix.valhalla.flatpakref

Offline / airgapped: every release also ships ready-to-install .flatpak bundles (x86_64 and aarch64). Grab one from the releases page and install:

flatpak install ./valhalla-<tag>-x86_64.flatpak

The bundle references its runtime, so the GNOME 49 platform is pulled from Flathub automatically on first install. Note that bundles are frozen at their tag: they do not receive updates through flatpak update — switch to the remote install above for updates.

To build the bundle locally instead:

# regenerate the vendored-crate source list from Cargo.lock
python3 flatpak/flatpak-cargo-generator.py Cargo.lock \
    -o flatpak/generated-sources.json

# build (offers to install the GNOME 49 Sdk and the rust-stable
# extension on first run)
flatpak-builder --force-clean --user --default-branch=stable \
    --repo=flatpak-repo flatpak-build flatpak/io.github.tunix.valhalla.json

# optional: single-file bundle to share or install
flatpak build-bundle \
    --runtime-repo=https://flathub.org/repo/flathub.flatpakrepo \
    flatpak-repo valhalla.flatpak io.github.tunix.valhalla stable
flatpak install ./valhalla.flatpak

A Flathub submission is planned on top of the same manifest.

Running

cargo run            # GUI
cargo run -- --daemon  # headless wallpaper refresh service

To refresh at boot/login without the window, enable Start at login in Preferences — Valhalla writes a desktop autostart entry that launches valhalla --daemon. The entry also shows up in the desktop's own "Startup Applications" list, so it can be toggled off from either side.

Settings

Stored in GSettings (gsettings list-recursively io.github.tunix.valhalla), API keys in the Secret Service (GNOME Keyring).

License

GPL-3.0