Show input modes in the keyboard indicator

default/input-methods/indicator.py

@@ -0,0 +1,66 @@
+"""Live Fcitx state for the existing keyboard layout widget."""
+
+import json
+import sys
+
+from gi.repository import Gio, GLib
+
+
+BUS = "org.fcitx.Fcitx5"
+INTERFACE = "org.fcitx.Fcitx.Controller1"
+
+
+def call(bus, method, args=None):
+  # Reading the bar must neither activate a stopped service nor wait indefinitely.
+  return bus.call_sync(BUS, "/controller", INTERFACE, method, args, None,
+                       Gio.DBusCallFlags.NO_AUTO_START, 1000, None).unpack()
+
+
+def snapshot(bus):
+  group = call(bus, "CurrentInputMethodGroup")[0]
+  methods = list(dict.fromkeys(item[0] for item in
+                              call(bus, "InputMethodGroupInfo", GLib.Variant("(s)", (group,)))[1]))
+  info = call(bus, "CurrentInputMethodInfo")
+  return {"methods": methods, "current": info[0], "name": info[1], "label": info[4], "language": info[5]}
+
+
+def cycle(bus):
+  state = snapshot(bus)
+  methods = state["methods"]
+  if len(methods) > 1 and state["current"] in methods:
+    following = methods[(methods.index(state["current"]) + 1) % len(methods)]
+    call(bus, "SetCurrentIM", GLib.Variant("(s)", (following,)))
+
+
+def watch(bus):
+  previous = None
+
+  def refresh():
+    nonlocal previous
+    try:
+      state = snapshot(bus)
+    except GLib.Error:
+      state = {"methods": [], "current": "", "name": "", "language": ""}
+    line = json.dumps(state, ensure_ascii=False)
+    if line != previous:
+      print(line, flush=True)
+      previous = line
+    return GLib.SOURCE_CONTINUE
+
+  # Fcitx's controller has no current-method-changed signal. Keep one bus
+  # connection open instead of spawning a command on every poll. Polling also
+  # follows per-application input contexts and recovers after service restarts.
+  refresh()
+  GLib.timeout_add(500, refresh)
+  GLib.MainLoop().run()
+
+
+if __name__ == "__main__":
+  try:
+    bus = Gio.bus_get_sync(Gio.BusType.SESSION, None)
+    if sys.argv[1:] == ["cycle"]:
+      cycle(bus)
+    else:
+      watch(bus)
+  except GLib.Error as error:
+    raise SystemExit(str(error))