"""
Unified WatchDog Service for monitoring UI Automation events.
Allows single instantiation to handle multiple monitors (Focus, Structure) safely in one STA thread.
"""
from windows_mcp.uia.core import _AutomationClient
from windows_mcp.uia.enums import TreeScope
from threading import Thread, Event
import comtypes.client
import comtypes
from .event_handlers import (
FocusChangedEventHandler,
StructureChangedEventHandler,
PropertyChangedEventHandler
)
class WatchDog:
def __init__(self):
self.uia_client = _AutomationClient.instance()
self.uia = self.uia_client.IUIAutomation
self.is_running = Event()
self.thread = None
# Callbacks
self._focus_callback = None
self._structure_callback = None
self._structure_element = None
self._property_callback = None
self._property_element = None
self._property_ids = None
# Internal state for tracking active handlers
self._focus_handler = None
self._structure_handler = None
self._active_structure_element = None
self._property_handler = None
self._active_property_element = None
self._active_property_ids = None
def __enter__(self):
self.start()
return self
def __exit__(self, exc_type, exc_val, exc_tb):
self.stop()
def start(self):
"""Start the watchdog service thread."""
if self.is_running.is_set():
return
self.is_running.set()
self.thread = Thread(target=self._run, name="WatchDogThread")
self.thread.daemon = True
self.thread.start()
def stop(self):
"""Stop the watchdog service thread."""
if not self.is_running.is_set():
return
self.is_running.clear()
if self.thread and self.thread.is_alive():
self.thread.join(timeout=2.0)
def set_focus_callback(self, callback):
"""Set the callback for focus changes. Pass None to disable."""
self._focus_callback = callback
def set_structure_callback(self, callback, element=None):
"""Set the callback for structure changes. Pass None to disable.
Optionally specify an element to watch (defaults to RootElement)."""
self._structure_callback = callback
self._structure_element = element
def set_property_callback(self, callback, element=None, property_ids=None):
"""Set the callback for property changes. Pass None to disable.
Optionally specify an element to watch (defaults to RootElement)
and a list of property IDs to monitor."""
self._property_callback = callback
self._property_element = element
self._property_ids = property_ids
def _run(self):
"""Main event loop running in a dedicated STA thread."""
comtypes.CoInitialize()
try:
while self.is_running.is_set():
# --- Focus Monitoring ---
if self._focus_callback and not self._focus_handler:
try:
self._focus_handler = FocusChangedEventHandler(self)
self.uia.AddFocusChangedEventHandler(None, self._focus_handler)
except Exception as e:
print(f"Failed to add focus handler: {e}")
elif not self._focus_callback and self._focus_handler:
try:
self.uia.RemoveFocusChangedEventHandler(self._focus_handler)
except Exception as e:
print(f"Failed to remove focus handler: {e}")
self._focus_handler = None
# --- Structure Monitoring ---
# Check if we need to UNREGISTER because configuration changed or disabled
config_changed = (self._structure_element != self._active_structure_element)
should_be_active = (self._structure_callback is not None)
is_active = (self._structure_handler is not None)
if is_active and (not should_be_active or config_changed):
try:
target = self._active_structure_element if self._active_structure_element else self.uia.GetRootElement()
self.uia.RemoveStructureChangedEventHandler(target, self._structure_handler)
except Exception as e:
print(f"Failed to remove structure handler: {e}")
self._structure_handler = None
self._active_structure_element = None
is_active = False
if should_be_active and not is_active:
try:
target = self._structure_element if self._structure_element else self.uia.GetRootElement()
scope = TreeScope.TreeScope_Subtree
self._structure_handler = StructureChangedEventHandler(self)
self.uia.AddStructureChangedEventHandler(target, scope, None, self._structure_handler)
self._active_structure_element = target
except Exception as e:
print(f"Failed to add structure handler: {e}")
# --- Property Monitoring ---
config_changed = (self._property_element != self._active_property_element) or \
(self._property_ids != self._active_property_ids)
should_be_active = (self._property_callback is not None)
is_active = (self._property_handler is not None)
if is_active and (not should_be_active or config_changed):
try:
target = self._active_property_element if self._active_property_element else self.uia.GetRootElement()
self.uia.RemovePropertyChangedEventHandler(target, self._property_handler)
except Exception as e:
print(f"Failed to remove property handler: {e}")
self._property_handler = None
self._active_property_element = None
self._active_property_ids = None
is_active = False
if should_be_active and not is_active:
try:
target = self._property_element if self._property_element else self.uia.GetRootElement()
scope = TreeScope.TreeScope_Subtree
# Monitor common properties if none specified
# 30005: Name, 30045: Value, 30093: LegacyIAccessibleVal, 30128: ToggleState
p_ids = self._property_ids if self._property_ids else [30005, 30045, 30093, 30128]
self._property_handler = PropertyChangedEventHandler(self)
self.uia.AddPropertyChangedEventHandler(target, scope, None, self._property_handler, p_ids)
self._active_property_element = target
self._active_property_ids = p_ids
except Exception as e:
print(f"Failed to add property handler: {e}")
# Pump events for this thread
comtypes.client.PumpEvents(0.1)
except Exception as e:
print(f"WatchDogService died: {e}")
finally:
# Cleanup handlers on exit
if self._focus_handler:
try:
self.uia.RemoveFocusChangedEventHandler(self._focus_handler)
except: pass
if self._structure_handler:
try:
target = self._active_structure_element if self._active_structure_element else self.uia.GetRootElement()
self.uia.RemoveStructureChangedEventHandler(target, self._structure_handler)
except: pass
if self._property_handler:
try:
target = self._active_property_element if self._active_property_element else self.uia.GetRootElement()
self.uia.RemovePropertyChangedEventHandler(target, self._property_handler)
except: pass
comtypes.CoUninitialize()
