swype-kbd

A swipe-typing (gesture/glide) on-screen keyboard for desktop Linux on Wayland, targeting Sway / wlroots. It renders as a zwlr_layer_shell_v1 surface, types into other apps via zwp_input_method_v2 + zwp_virtual_keyboard_v1, and decodes word gestures with a SHARK2-style shape-matching decoder.

See ARCHITECTURE.md for the design and milestone history.

Features

• Swipe typing — glide across a word's letters; on release a SHARK2-style decoder (shape + location + endpoint channels, frequency prior, and velocity-weighted matching) commits the most likely word plus a space. A suggestion bar shows alternates — tap to replace.
• Tap typing with predictive word completions in the suggestion bar.
• Next-word prediction — a learned bigram model offers the word you usually type next, right after you finish a word.
• Pointer and touch input (wl_pointer and wl_touch).
• Input layers — Shift (one-shot → caps-lock → off) and two symbol pages cover the full ASCII set, through both the input-method and virtual-keyboard channels.
• Smart typing — gesture words commit with a trailing space; punctuation tucks against the word (hello . → hello.); the first letter after . ! ? or Enter auto-capitalizes.
• Learns your tendencies — every word you accept (swipe, complete, or tap out) gently rises in frequency, and corrections converge a confusable pair. Words you type that aren't in the dictionary join a personal dictionary after a few uses, becoming swipeable and completable like any other word. All of it persists under $XDG_STATE_HOME/swype-kbd/ (learned.txt, personal.txt, bigrams.txt), written 0600 (owner-only).
• Privacy-aware — text typed into password / PIN / sensitive fields (per the input-method content_type) is never learned or persisted. For a global opt-out regardless of field tagging, run with --no-learn, which disables personalization entirely and reads/writes no state files.
• One-tap undo — Backspace right after a committed word removes it whole.
• Polished UI — anti-aliased TrueType labels, rounded keys with depth, a key pop-up preview, and a glowing gesture trail, all from a dependency-light software rasterizer with damage-tracked repaints.
• Real dictionary, low latency — loads a ~50k-word unigram frequency list at runtime (49,945 templates build in ~0.25 s); decode mean ~3 ms, p99 ~7 ms, under a 30 ms budget. Synthetic accuracy ≈98% top-1, 100% top-3 on common words. Override the list with SWYPE_DICT.

Requirements

• A wlroots-based Wayland compositor — Sway, Hyprland, river, Wayfire, … — exposing zwlr_layer_shell_v1, zwp_input_method_v2, and zwp_virtual_keyboard_v1. It does not run on GNOME, KDE Plasma, or X11.
• A Rust toolchain to build (stable).

Build & test

cargo build --release
cargo test          # decoder + app unit tests

Run

Launch it from a terminal inside your Sway/wlroots session (so WAYLAND_DISPLAY is set):

cargo run --release -p swype-kbd
# or: ./target/release/swype-kbd

A keyboard docks to the bottom of the screen and types into whatever app has focus. Tap keys to type, or glide across letters to swipe a word; the suggestion bar offers alternates and completions. Decode/debug traces print to stdout. Exit with Ctrl-C.

The dictionary is found via $SWYPE_DICT, then a path next to the binary, then ./data/; a small embedded list is the fallback so the binary also works standalone.

Options

--always-on   Stay docked even when no field is focused (default: auto-hide to a
              slim tap handle, popping up on typing context).
--no-learn    Disable all personalization — no state files are read or written.
              (Password/sensitive fields are excluded automatically regardless.)
--help, -h    Full usage.

Layout

• crates/decoder (swype-decoder) — the pure, Wayland-free gesture decoder and shared keyboard geometry. Fully unit-tested.
• crates/app (swype-kbd) — the Wayland layer-shell binary: software rasterizer (anti-aliased text, rounded keys), pointer/touch hit-testing, and text injection.

Ideas / not yet done

• Multi-touch (two-thumb) gesturing and a number row.
• Theming and sizing config (height, colors, light theme, landscape).
• Packaging for distribution (release tarball / distro packages / autostart).
• A cached static-background render pass, if the per-motion repaint is ever too heavy on low-end hardware.

Credits

Bundles DejaVu Sans for UI text; see crates/app/assets/DejaVuSans.LICENSE.