change timer for smoother mouse follow

source/_magnifier/magnifier.py

@@ -15,6 +15,7 @@
 import ui
 import speech
 import screenCurtain
+from winBindings import winmm
 from winAPI import _displayTracking
 from winAPI._displayTracking import OrientationState, getPrimaryDisplayOrientation
 from .utils.types import (
@@ -38,7 +39,7 @@
 
 
 class Magnifier:
-	_TIMER_INTERVAL_MS: int = 12
+	_TIMER_INTERVAL_MS: int = 8
 	_MARGIN_BORDER: int = 50
 	_MAX_CONSECUTIVE_ERRORS: int = 3
 	_MAGNIFIED_VIEW: MagnifiedView
@@ -182,14 +183,17 @@ def _startMagnifier(self) -> None:
 			ui.message(message, speechPriority=speech.priorities.Spri.NOW)
 			return
 
+		result = winmm.timeBeginPeriod(1)
+		if result != winmm.TIMERR_NOERROR:
+			log.warning(f"timeBeginPeriod(1) failed with code {result} — timer resolution stays at ~15ms")
+
 		self._isActive = True
 		self.currentCoordinates = self._focusManager.getCurrentFocusCoordinates()
 
 	def _updateMagnifier(self) -> None:
 		"""
 		Update the magnifier position and content.
-		This method is called repeatedly by the timer.
-		On transient errors (below threshold): reschedules itself to keep running.
+		This method is called repeatedly by the repeating timer.
 		On repeated errors (at threshold): delegates rescheduling to _attemptRecovery.
 		"""
 		if not self._isActive:
@@ -225,8 +229,6 @@ def _updateMagnifier(self) -> None:
 				f"Transient error updating magnifier ({self._consecutiveErrors}/{self._MAX_CONSECUTIVE_ERRORS})",
 				exc_info=True,
 			)
-		# Always reschedule the timer to keep the magnifier alive
-		self._startTimer(self._updateMagnifier)
 
 	def _doUpdate(self) -> None:
 		"""
@@ -253,6 +255,7 @@ def _stopMagnifier(self) -> None:
 		if not self._isActive:
 			return
 		self._stopTimer()
+		winmm.timeEndPeriod(1)
 		self._isActive = False
 		# Unregister from display changes
 		_displayTracking.displayChanged.unregister(self._onDisplayChanged)
@@ -367,7 +370,7 @@ def _startTimer(self, callback: Callable[[], None] = None) -> None:
 		self._stopTimer()
 		self._timer = wx.Timer()
 		self._timer.Bind(wx.EVT_TIMER, lambda evt: callback())
-		self._timer.Start(self._TIMER_INTERVAL_MS, oneShot=True)
+		self._timer.Start(self._TIMER_INTERVAL_MS, oneShot=False)
 
 	def _stopTimer(self) -> None:
 		"""

source/winBindings/winmm.py

@@ -19,7 +19,7 @@
 
 DWORD_PTR = c_size_t
 MMRESULT = c_long
-
+TIMERR_NOERROR: int = 0
 
 dll = windll.winmm
 
@@ -48,3 +48,29 @@
 	DWORD_PTR,  # dw1: Message parameter (DWORD_PTR)
 	DWORD_PTR,  # dw2: Message parameter (DWORD_PTR)
 )
+
+timeBeginPeriod = WINFUNCTYPE(None)(("timeBeginPeriod", dll))
+"""
+Sets the minimum timer resolution for the application.
+Must be matched with a corresponding call to timeEndPeriod using the same uPeriod value.
+
+.. seealso::
+	https://learn.microsoft.com/en-us/windows/win32/api/timeapi/nf-timeapi-timebeginperiod
+"""
+timeBeginPeriod.restype = MMRESULT
+timeBeginPeriod.argtypes = (
+	UINT,  # uPeriod: Minimum timer resolution, in milliseconds
+)
+
+timeEndPeriod = WINFUNCTYPE(None)(("timeEndPeriod", dll))
+"""
+Clears a previously set minimum timer resolution.
+uPeriod must match the value passed to the corresponding timeBeginPeriod call.
+
+.. seealso::
+	https://learn.microsoft.com/en-us/windows/win32/api/timeapi/nf-timeapi-timeendperiod
+"""
+timeEndPeriod.restype = MMRESULT
+timeEndPeriod.argtypes = (
+	UINT,  # uPeriod: Minimum timer resolution to clear, in milliseconds
+)

tests/unit/test_magnifier/test_fullscreenMagnifier.py

@@ -263,27 +263,19 @@ def testAttemptRecoveryFailureStopsMagnifier(self):
 		self.assertEqual(magnifier._consecutiveErrors, 0)
 
 	def testUpdateLoopSurvivesSingleDoUpdateError(self):
-		"""A single _doUpdate error does not kill the update loop."""
+		"""A single _doUpdate error increments the counter; a subsequent success resets it."""
 		magnifier = FullScreenMagnifier()
 		magnifier._startMagnifier()
-		magnifier._startTimer = MagicMock()
 		magnifier._focusManager.getCurrentFocusCoordinates = MagicMock(
 			return_value=(100, 200),
 		)
-
-		# First call fails, second succeeds
 		magnifier._doUpdate = MagicMock(side_effect=[OSError("Transient"), None])
 
-		# First update — error
 		magnifier._updateMagnifier()
 		self.assertEqual(magnifier._consecutiveErrors, 1)
-		magnifier._startTimer.assert_called_with(magnifier._updateMagnifier)
 
-		# Second update — success
-		magnifier._startTimer.reset_mock()
 		magnifier._updateMagnifier()
 		self.assertEqual(magnifier._consecutiveErrors, 0)
-		magnifier._startTimer.assert_called_with(magnifier._updateMagnifier)
 
 		magnifier._stopMagnifier()
 

tests/unit/test_magnifier/test_magnifier.py

@@ -7,6 +7,7 @@
 from _magnifier.magnifier import Magnifier
 from _magnifier.utils.types import Filter, Direction, Coordinates, MagnifierAction
 from comtypes import COMError
+import time
 import unittest
 from winAPI._displayTracking import getPrimaryDisplayOrientation
 from unittest.mock import MagicMock, patch
@@ -33,9 +34,14 @@ def setUp(self):
 			mock.MagUninitialize.return_value = True
 			mock.MagSetFullscreenTransform.return_value = True
 			mock.MagSetFullscreenColorEffect.return_value = True
+		self.winmm_patcher = patch("_magnifier.magnifier.winmm")
+		self.mock_winmm = self.winmm_patcher.start()
+		self.mock_winmm.timeBeginPeriod.return_value = 0
+		self.mock_winmm.TIMERR_NOERROR = 0
 
 	def tearDown(self):
 		"""Cleanup after each test."""
+		self.winmm_patcher.stop()
 		self.mag_fs_patcher.stop()
 		self.mag_patcher.stop()
 
@@ -144,29 +150,22 @@ def testUpdateMagnifier(self):
 			2,
 		)
 		self.magnifier._doUpdate.assert_called_once()
-		self.magnifier._startTimer.assert_called_once_with(
-			self.magnifier._updateMagnifier,
-		)
+		self.magnifier._startTimer.assert_not_called()
 		self.assertEqual(self.magnifier.currentCoordinates, focusCoords)
 		# Successful update should reset error counter
 		self.assertEqual(self.magnifier._consecutiveErrors, 0)
 
 	def testUpdateMagnifierResumesAfterSingleError(self):
-		"""Timer must always be rescheduled even when _doUpdate raises an exception."""
+		"""Transient errors below the threshold increment the error counter without triggering recovery."""
 		self.magnifier._isActive = True
 		focusCoords = Coordinates(self.screenWidth // 2, self.screenHeight // 2)
 		self.magnifier._focusManager.getCurrentFocusCoordinates = MagicMock(
 			return_value=focusCoords,
 		)
 		self.magnifier._doUpdate = MagicMock(side_effect=OSError("COM failure"))
-		self.magnifier._startTimer = MagicMock()
 
 		self.magnifier._updateMagnifier()
 
-		# Timer must still be rescheduled despite the error
-		self.magnifier._startTimer.assert_called_once_with(
-			self.magnifier._updateMagnifier,
-		)
 		self.assertEqual(self.magnifier._consecutiveErrors, 1)
 
 	def testUpdateMagnifierTriggersRecoveryAfterMaxErrors(self):
@@ -189,18 +188,16 @@ def testUpdateMagnifierTriggersRecoveryAfterMaxErrors(self):
 		self.magnifier._startTimer.assert_not_called()
 
 	def testUpdateMagnifierCatchesCOMError(self):
-		"""COMError from UIA must be caught and the timer rescheduled."""
+		"""COMError is caught like OSError and increments the consecutive error counter."""
 		self.magnifier._isActive = True
 		focusCoords = Coordinates(self.screenWidth // 2, self.screenHeight // 2)
 		self.magnifier._focusManager.getCurrentFocusCoordinates = MagicMock(
 			return_value=focusCoords,
 		)
 		self.magnifier._doUpdate = MagicMock(side_effect=COMError(-2147417848, "RPC_E_DISCONNECTED", None))
-		self.magnifier._startTimer = MagicMock()
 
 		self.magnifier._updateMagnifier()
 
-		self.magnifier._startTimer.assert_called_once_with(self.magnifier._updateMagnifier)
 		self.assertEqual(self.magnifier._consecutiveErrors, 1)
 
 	def testUpdateMagnifierRecoveryFailureSafelyRestartsTimer(self):
@@ -229,13 +226,11 @@ def testUpdateMagnifierResetsErrorCountOnSuccess(self):
 		self.magnifier._focusManager.getCurrentFocusCoordinates = MagicMock(
 			return_value=focusCoords,
 		)
-		self.magnifier._doUpdate = MagicMock()  # Success
-		self.magnifier._startTimer = MagicMock()
+		self.magnifier._doUpdate = MagicMock()
 
 		self.magnifier._updateMagnifier()
 
 		self.assertEqual(self.magnifier._consecutiveErrors, 0)
-		self.magnifier._startTimer.assert_called_once()
 
 	def testAttemptRecoveryBase(self):
 		"""Base _attemptRecovery resets errors and restarts timer."""
@@ -269,6 +264,21 @@ def testStopMagnifier(self):
 		self.magnifier._stopTimer.assert_called_once()
 		self.assertFalse(self.magnifier._isActive)
 
+	def testTimeBeginPeriodReducesTimerResolution(self):
+		"""timeBeginPeriod(1) must reduce actual sleep(1ms) duration below 5ms."""
+		from winBindings import winmm as real_winmm
+
+		real_winmm.timeBeginPeriod(1)
+		try:
+			durations_ms = []
+			for _ in range(20):
+				t0 = time.perf_counter()
+				time.sleep(0.001)
+				durations_ms.append((time.perf_counter() - t0) * 1000)
+			self.assertLess(min(durations_ms), 5.0)
+		finally:
+			real_winmm.timeEndPeriod(1)
+
 	def testZoom(self):
 		"""zoom in and out with valid values and check boundaries."""
 		# Set initial zoom to 1.0 for predictable testing