Add synthDriverHandler.synthChanged extension point

source/synthDriverHandler.py

@@ -472,6 +472,7 @@ def setSynth(name: Optional[str], isFallback: bool = False):
 		if not isFallback:
 			config.conf["speech"]["synth"] = name
 		log.info(f"Loaded synthDriver {_curSynth.name}")
+		synthChanged.notify(synth=_curSynth, audioOutputDevice=_audioOutputDevice, isFallback=isFallback)
 		return True
 	# As there was an error loading this synth:
 	elif prevSynthName:
@@ -534,3 +535,16 @@ def isDebugForSynthDriver():
 #: Handlers are called with one keyword argument:
 #: synth: The L{SynthDriver} which reached the index.
 synthDoneSpeaking = extensionPoints.Action()
+
+synthChanged = extensionPoints.Action()
+"""
+Action that allows components or add-ons to be notified of synthesizer changes.
+For example, when a system is controlled by a remote system and the remote system switches synth,
+The local system should be notified about synth parameters at the remote system.
+@param synth: The new synthesizer driver
+@type synth: L{SynthDriver}
+@param audioOutputDevice: The identifier of the audio output device used for this synth.
+@type audioOutputDevice: str
+@param isFallback: Whether the synth is set as fallback synth due to another synth's failure
+@type isFallback: bool
+"""

tests/unit/test_synthDriverHandler.py

@@ -1,7 +1,7 @@
 # A part of NonVisual Desktop Access (NVDA)
 # This file is covered by the GNU General Public License.
 # See the file COPYING for more details.
-# Copyright (C) 2021 NV Access Limited
+# Copyright (C) 2021-2023 NV Access Limited, Leonard de RUijter
 
 """Unit tests for the synthDriverHandler
 """
@@ -12,6 +12,7 @@
 from synthDrivers.oneCore import SynthDriver as OneCoreSynthDriver
 from typing import Callable
 import unittest
+from .extensionPointTestHelpers import actionTester
 
 FAKE_DEFAULT_LANG = "fakeDefault"
 FAKE_DEFAULT_SYNTH_NAME = "defaultSynth"
@@ -117,3 +118,17 @@ def test_setSynth_auto_fallback_ifOneCoreDoesntSupportDefaultLanguage(self):
 		synthDriverHandler.setSynth(None)  # reset the synth so there is no fallback
 		synthDriverHandler.setSynth("auto")
 		self.assertEqual(synthDriverHandler.getSynth().name, "espeak")
+
+	def test_synthChangedExtensionPoint(self):
+		expectedKwargs = dict(
+			isFallback=False,
+			audioOutputDevice="default"
+		)
+
+		with actionTester(
+			self,
+			synthDriverHandler.synthChanged,
+			useAssertDictContainsSubset=True,
+			**expectedKwargs
+		):
+			synthDriverHandler.setSynth("auto")