RGDS Virtual Keyboard

A touchscreen virtual keyboard for the Anbernic RG DS running ROCKNIX.

Renders a phone-style keyboard on the bottom screen (DSI-1) and injects keystrokes to whatever app is running on the top screen. Toggle it on/off anytime with R3 (right stick click).

What's New in v5

• Near-zero idle CPU — epoll-based event loop sleeps when hidden, 30fps cap when visible
• Dirty-region rendering — only redraws keys that change state, via GPU render-target texture
• 8 dark themes — Tokyo Night, Catppuccin, Dracula, Nord, Gruvbox, One Dark, Solarized, Midnight
• Auto-detect devices — finds touchscreen and joypad by capability, no more hardcoded paths
• Persistent settings — theme, brightness, and repeat rates saved as JSON
• Signal control — SIGUSR1/2/SIGRTMIN for hide/show/toggle (wvkbd-compatible)
• Haptic feedback — vibration on keypress (when hardware supports it)
• GC-tuned daemon — freezes garbage collector after init for consistent latency
• SDL2 render batching — minimises GPU draw calls

Requirements

• Anbernic RG DS (dual-screen, RK3568)
• ROCKNIX nightly with RG DS support (tested on 20260314+)
• SSH access to the device

Quick Install

# Transfer files to the device
scp -r . root@<DEVICE_IP>:/tmp/rgds-keyboard

# SSH in and run the installer
ssh root@<DEVICE_IP>
bash /tmp/rgds-keyboard/install.sh

Then in EmulationStation: go to Ports → Keyboard to start/stop.

Usage

From EmulationStation

1. Navigate to Ports
2. Select Keyboard to start the daemon
3. Press R3 anytime to show/hide the keyboard
4. Select Keyboard again to stop

From SSH

bash /storage/rgds-keyboard.sh start
bash /storage/rgds-keyboard.sh stop
bash /storage/rgds-keyboard.sh restart
bash /storage/rgds-keyboard.sh show
bash /storage/rgds-keyboard.sh hide
bash /storage/rgds-keyboard.sh toggle

Signal Control

PID=$(cat /tmp/rgds_keyboard.pid)
kill -USR1 $PID   # hide
kill -USR2 $PID   # show
kill -RTMIN $PID   # toggle

Themes

Eight WCAG-AA-compliant dark palettes, selectable via config file:

Theme	Background	Accent
Tokyo Night (default)	#1A1B26	#7AA2F7
Catppuccin Mocha	#1E1E2E	#CBA6F7
Dracula	#282A36	#BD93F9
Nord	#2E3440	#88C0D0
Gruvbox Dark	#282828	#FE8019
One Dark	#282C34	#61AFEF
Solarized Dark	#002B36	#268BD2
Midnight OLED	#000000	#0A84FF

Edit /storage/.config/rgds-keyboard/config.json to change themes:

{
  "theme": "catppuccin"
}

Layout

Phone-style QWERTY with four layers:

Main (ABC)

 q  w  e  r  t  y  u  i  o  p
   a  s  d  f  g  h  j  k  l
 ⇧  z  x  c  v  b  n  m  ⌫
  #+  ,      SPACE       .  RET
  1  2  3  4  5  6  7  8  9  0
 TAB ESC NAV  -  ?  !  @

Shift

Same letters (uppercase), auto-returns after one letter. Number row becomes ! @ # $ % ^ & * ( ).

Symbols (#+)

Three rows of brackets, punctuation, and operators.

Nav

Arrow keys, Home, End, Delete, Insert — for text editing.

Configuration

Settings persist in /storage/.config/rgds-keyboard/config.json:

Key	Default	Description
theme	"tokyonight"	Colour theme name
brightness	1.0	DSI-1 brightness (0.0–1.0)
haptic_enabled	true	Vibration on keypress
repeat_delay	0.4	Seconds before key repeat starts
repeat_rate	0.05	Seconds between repeats
touch_device	""	Override touchscreen path (empty = auto)
joypad_device	""	Override joypad path (empty = auto)

Architecture

Touch (auto-detected Goodix touchscreen)
  → Python reads multitouch events via epoll/selectors
  → Maps touch coordinates to key grid
  → Dirty-region renderer updates only changed keys
  → Writes EV_KEY events to /dev/uinput
  → Kernel delivers to Sway compositor
  → Sway delivers to focused app on top screen

Performance

State	CPU Usage	Mechanism
Hidden	~0%	selectors.select() blocks indefinitely
Visible, idle	<1%	30fps timeout, no render if clean
Active typing	~3–5%	Dirty-region redraws only pressed key

Files

File	Installs to	Purpose
main.py	/storage/rgds-keyboard/	Application entry point, event loop
config.py	/storage/rgds-keyboard/	Themes, settings, JSON persistence
devices.py	/storage/rgds-keyboard/	Auto-detect input devices
font.py	/storage/rgds-keyboard/	5×7 bitmap font data
layouts.py	/storage/rgds-keyboard/	Keyboard layout definitions
renderer.py	/storage/rgds-keyboard/	Dirty-region rendering engine
sdl2.py	/storage/rgds-keyboard/	SDL2 ctypes bindings
uinput_kb.py	/storage/rgds-keyboard/	Virtual keyboard via uinput
rgds-keyboard.sh	/storage/	CLI launcher
Keyboard.sh	/storage/roms/ports/	EmulationStation entry
install.sh	—	One-command installer

Compatibility

Tested and working with:

App	Type	Status
NetSurf	Wayland browser	✅
foot	Wayland terminal	✅
ScummVM	SDL game engine	✅
Counter-Strike 1.6	PortMaster port	✅

Should work with any app that receives keyboard input via Sway/Wayland or evdev.

Uninstall

rm -rf /storage/rgds-keyboard
rm /storage/rgds-keyboard.sh
rm /storage/roms/ports/Keyboard.sh
rm -rf /storage/.config/rgds-keyboard

Troubleshooting

Problem	Fix
Keyboard doesn't appear	Check /tmp/rgds_keyboard.log
Bottom screen stays off	swaymsg 'output DSI-1 power on' via SSH
Controls frozen after crash	Reboot the device
Wrong touchscreen detected	Set touch_device in config.json
No input in apps	Verify with evtest while tapping keys
Shortcut missing after reboot	Ensure Keyboard.sh is in /storage/roms/ports/

Contributing

Areas for improvement:

• Swipe gestures — swipe-left for backspace-word, swipe-down to hide
• Long-press alternate characters — accented letters (é, ñ, ü)
• Multi-language layouts — AZERTY, QWERTZ, Nordic, Cyrillic
• FreeType font rendering — TTF support via SDL_ttf
• Mouse emulation — touch-to-cursor mode
• On-screen theme picker — select themes without editing config

PRs welcome!

License

MIT — free to use, modify, and distribute.

Acknowledgments

Built for the ROCKNIX community and the Anbernic RG DS.