uboat-settings-editor

A small native editor for U-Boat mod settings .xlsx files. Lists every parameter from the file grouped by /Section, lets you toggle booleans as checkboxes and edit other values as text, and writes the file back with surgical edits — only the value cells you actually changed are rewritten; everything else in the workbook (styles, column widths, the description column, blank separator rows, section headers, shared strings you didn't touch) is passed through untouched.

Built with Rust + Slint. Runs on Linux and Windows; the Linux build is primarily targeted at KDE Plasma but works on any desktop.

Build prerequisites

• Rust 1.85+ (2024 edition). rustup is the easy way.
• Optional: Qt 6 development package if you want the native Breeze look on KDE. Install your distro's Qt 6 base + dev package, then build with --features qt (see below). Without it you get Slint's bundled fluent style, which has zero system dependencies and looks reasonable everywhere.

Distro packages providing qmake6 and Qt 6 headers:

Distro	Package
Arch / Manjaro	qt6-base
Debian / Kubuntu	qt6-base-dev
Fedora	qt6-qtbase-devel
openSUSE	qt6-base-devel

The first build pulls a few hundred MB of crates from crates.io and takes several minutes on a clean cache. Incremental rebuilds are fast.

Building

# Default — fluent style, no system deps:
cargo build --release

# Native KDE Breeze look — requires qt6-base + qmake6:
cargo build --release --features qt

# Other Slint styles (override style without changing features):
SLINT_STYLE=cosmic   cargo build --release
SLINT_STYLE=material cargo build --release

The binary lands at target/release/uboat-settings-editor. Stripped, it's a single file in the low tens of MB depending on which style is compiled in.

Cross-compiling for Windows

The default fluent style cross-compiles cleanly from Linux. There's a preconfigured linker setting in .cargo/config.toml so it's a one-liner:

rustup target add x86_64-pc-windows-gnu
sudo pacman -S mingw-w64-gcc                # or: apt install mingw-w64
cargo build --release --target x86_64-pc-windows-gnu

The .exe lands at target/x86_64-pc-windows-gnu/release/uboat-settings-editor.exe. It depends only on standard Windows libraries (no Qt). Do not add --features qt when targeting Windows — that would require a Windows Qt 6 SDK and complicate things considerably.

Installing on Arch Linux

A ready-to-use PKGBUILD is included that tracks the main branch of the upstream git repo and builds with --features qt:

# From inside a clone of the repo:
makepkg -si

This installs:

• /usr/bin/uboat-settings-editor
• /usr/share/applications/uboat-settings-editor.desktop — KDE menu entry
• /usr/share/doc/uboat-settings-editor-git/README.md

To uninstall: sudo pacman -R uboat-settings-editor-git.

To pin to a specific commit or tag instead of tracking main, edit the source line and pkgver() function — comments in the PKGBUILD explain.

Running

uboat-settings-editor

Then Open…, pick a mod's .xlsx, edit, Save. The window title shows a • while there are unsaved changes; closing the window with unsaved changes prompts for confirmation. Reload discards unsaved changes and re-reads from disk.

Backups

Before any save, the current on-disk version is copied to .backups/<filename>.<YYYYMMDD-HHMMSS>.xlsx next to the file. The 10 most recent backups per file are kept; older ones are pruned automatically.

Tests

cargo test

The test suite round-trips real BDUCR and UBE settings files through load → edit → save → re-load and asserts both that changes persisted and that unchanged cells (units, descriptions, blank separator rows, other parameters) survived untouched.

What the tool guarantees about the saved file

• The set of <c> cells whose values you changed is the only set rewritten. All other cells are byte-identical to the source.
• For booleans, the literal strings "True" and "False" are preserved (these are stored as shared strings in the workbook, exactly the way the game's mod loader expects them).
• For numeric cells whose new value is still numeric, the cell stays numeric. If you type non-numeric text into a former numeric field, the cell is rewritten as a shared string — the file remains valid XLSX, and you can read it back; whether the mod tolerates the new type is on you.
• Section headers (/Debug, /Features, …) and the description column are never edited by the tool.
• Shared strings are only appended to (never reordered or removed), so existing index references remain valid.

Limitations

• First worksheet only (xl/worksheets/sheet1.xml). Both observed mod files put everything there; multi-sheet workbooks aren't supported.
• The UI shows the description column from column C, read-only. There's no way to edit it from this tool — by design.
• No undo beyond Reload (which discards all in-session changes) and the on-disk backup history.

Project layout

.
├── .cargo/config.toml          # Cross-compile linker config
├── Cargo.toml                  # crate manifest, with [features] qt
├── Cargo.lock                  # pinned dependency versions
├── PKGBUILD                    # Arch package definition
├── build.rs                    # compiles ui/app.slint at build time
├── packaging/
│   └── uboat-settings-editor.desktop
├── ui/
│   └── app.slint               # Slint UI definition
├── src/
│   ├── main.rs                 # entry point, UI <-> document glue
│   ├── model.rs                # Document / Section / Parameter types
│   └── xlsx.rs                 # surgical xlsx load + save, with tests
└── tests/data/                 # real mod files used by the test suite

License

MIT. See LICENSE.