rcalc

Desktop calculator for Linux/Windows/macOS, inspired by the Windows Calculator (standard mode).

Built with Rust + Slint.

Run

cargo run --release
# or
./dist/rcalc

Install as a Debian package

./scripts/build-deb.sh                            # → dist/rcalc_<version>-<rev>_<arch>.deb
sudo apt install ./dist/rcalc_*_amd64.deb
rcalc                                             # or start it from the application menu

The binary is compiled in an Ubuntu 22.04 container (Docker) by default, so the package keeps a glibc 2.35 baseline and installs on Ubuntu 22.04 / 24.04 / 26.04. Depends: are generated from the ELF with dpkg-shlibdeps.

Menu/taskbar icons come from ico/ — every PNG there is placed into the hicolor slot matching its real pixel size (file names do not matter), and the remaining smaller sizes are downsampled from the biggest one. Without ico/ the icons are resized from assets/icon.png. The icon inside the window (ui/app.slint) and the Windows rcalc.exe icon still use assets/.

Useful switches:

Variable	Effect
DEB_REVISION=	packaging revision, 1 by default → Version: 0.1.28-1
REPO=1	also write dist/Packages(.gz) so dist/ works as a local apt repo
SKIP_DOCKER=1	build on the host (needs this host's glibc on the target)
PREBUILT=1	package the existing dist/rcalc, no compile
NO_STRIP=1	keep symbols (bigger package)
KEEP_STAGE=1	leave dist/deb-root/ for inspection
DOCKER_IMAGE=	other build image, e.g. debian:12 for an older baseline
DEB_MAINTAINER=	"Name <mail>" in Maintainer: (default: git user)

Version and updates

Package version = <version from Cargo.toml>-<DEB_REVISION>, e.g. 0.1.28-1.

• changed app code → bump version in Cargo.toml (it is also the window title);
• changed only packaging (icon, .desktop, Depends, rebuilt binary) → DEB_REVISION=2.

dpkg compares these in order (0.1.28-1 < 0.1.28-2 < 0.1.29-1, and 0.1.9 < 0.1.10), so every new build is an upgrade, never a downgrade. The script prints the resulting upgrade path and warns if the version being built is not newer than the installed one — an apt upgrade of such a package does nothing. Release notes live in packaging/deb/changelog and are installed as /usr/share/doc/rcalc/changelog.Debian.gz.

Update in place (config in ~/.config/rcalc/config.json is a user file, it survives):

sudo apt install ./dist/rcalc_0.1.28-2_amd64.deb

Or keep dist/ as a local repository and update with plain apt (build with REPO=1, then point apt at the folder):

echo 'deb [trusted=yes] file:/path/to/RCalc/dist ./' | sudo tee /etc/apt/sources.list.d/rcalc.list
sudo apt update && sudo apt install rcalc          # later: sudo apt upgrade

If scripts/install-desktop.sh was ever run, ~/.local/bin/rcalc (a symlink to dist/rcalc) shadows /usr/bin/rcalc — remove it after switching to the package, otherwise rcalc in the terminal still starts the old binary. The script warns about this during the build.

Icon (Linux / Wayland)

On Wayland the window icon property is ignored — the desktop uses .desktop + app_id. Install once:

./scripts/install-desktop.sh

Then start rcalc from the app menu (or ~/.local/bin/rcalc), not by clicking a random binary path, so KDE/GNOME can match app_id=rcalc to rcalc.desktop and show the icon.

Features

• Modes: Standard, Engineering, Programmer, Convert, CRC, Settings
• Standard: + − × ÷, %, ±, 1/x, x², √x, memory, formula panel
• Engineering: trig functions, log/pow, DEG/RAD, SI prefixes
• Programmer: simultaneous HEX / DEC / OCT / BIN, sizes QWORD / DWORD / DINT / WORD / INT / BYTE, bitwise ops, clickable bits (WORD/DWORD — unsigned DEC; INT/DINT — signed)
• Convert: float32 ↔ two 16-bit words with endian AB CD / CD AB / BA DC / DC BA
• Convert → Ratio: float → minimal num/den for electronic gear (Byte≤255 / Word≤65535)
• Convert → ASCII: Char ↔ Hex ↔ Dec (control names for NUL…DEL)
• CRC: Modbus RTU CRC-16 + Modbus ASCII LRC from hex bytes (01 03 00 00 00 0A)
• Keyboard input

Project layout

• src/engine.rs — standard calculator logic
• src/programmer.rs — programmer mode logic
• src/convert.rs — float32 / word endian convert
• src/main.rs — UI wiring
• ui/app.slint — Slint interface
• dist/rcalc — release binary
• scripts/build-deb.sh + packaging/deb/ — .deb package (control, desktop file, AppStream metainfo, maintainer scripts)
• scripts/build-appimage.sh — portable AppImage
• scripts/install-desktop.sh — per-user launcher + icon (no root needed)