First commit

README.md

@@ -1,2 +1,8 @@
 # cutiepi-button-handler
-Simple button handling service for the CutiePi button events
+
+This script handles button press events on a CutiePi tablet and toggles the display on/off upon pressure.
+
+## Installation
+
+Just copy `bin/cutiepi-button-handler` somewhere in your `PATH` (default: `~/bin`) and start it. Button support should work out of the box.
+

bin/cutiepi-button-handler

@@ -0,0 +1,64 @@
+#!/usr/bin/env python
+
+import os
+import re
+import subprocess
+
+from gi.repository import GLib
+from dbus import SessionBus
+from dbus.mainloop.glib import DBusGMainLoop
+
+previous_xrandr = 'xrandr --output DSI-1 --auto'
+
+
+def get_current_xrandr() -> str:
+    proc = subprocess.Popen(['unxrandr'], stdout=subprocess.PIPE)
+    return proc.communicate()[0].decode().strip()
+
+
+def is_display_on() -> bool:
+    proc = subprocess.Popen(['xrandr', '-q'], stdout=subprocess.PIPE)
+    out = proc.communicate()[0].decode().strip()
+    lines = [
+        line for line in out.split('\n')
+        if line.startswith('DSI-1 ')
+    ]
+
+    assert lines, 'Display DSI-1 not found'
+    m = re.search(r'^DSI-1\s+(connected\s+)?(primary\s+)?\d+x\d+\+\d+\+\d+', lines[0])
+    return m is not None
+
+
+def signal_handler(name, value):
+    global previous_xrandr
+    if name != 'button':
+        return
+
+    is_on = is_display_on()
+    if is_on:
+        previous_xrandr = get_current_xrandr()
+        os.system('xrandr --output DSI-1 --off')
+    else:
+        os.system(previous_xrandr)
+
+
+def main():
+    xrandr = get_current_xrandr()
+
+    loop = DBusGMainLoop()
+    bus = SessionBus(mainloop=loop)
+    bus.add_signal_receiver(
+        signal_handler, 'updateEvent',
+        'io.cutiepi.interface', path='/mcu'
+    )
+
+    loop = GLib.MainLoop()
+
+    try:
+        loop.run()
+    finally:
+        loop.quit()
+
+
+if __name__ == '__main__':
+    main()

systemd/cutiepi-button-handler.service

@@ -0,0 +1,19 @@
+# Copy or symlink this systemd service to ~/.config/systemd/user
+# (create the folder if it doesn't exist).
+# Start with: systemctl --user start cutiepi-button-handler
+# Stop with: systemctl --user stop cutiepi-button-handler
+# Enable at startup with: systemctl --user cutiepi-button-handler
+# Disable at startup with: systemctl --user cutiepi-button-handler
+
+[Unit]
+Description=Manage screen on/off logic upon button press on the CutiePi
+After=graphical.target
+
+[Service]
+ExecStart=/home/pi/bin/cutiepi-button-handler
+Restart=always
+RestartSec=5
+
+[Install]
+WantedBy=default.target
+