Abstract the TTSBackend type

src/calibre/gui2/tts2/manager.py

@@ -4,13 +4,16 @@
 
 from collections import deque
 from contextlib import contextmanager
-from typing import NamedTuple
+from typing import NamedTuple, TYPE_CHECKING
 
 from qt.core import QApplication, QDialog, QObject, QTextToSpeech, QWidget, pyqtSignal
 
 from calibre.gui2 import error_dialog
 from calibre.gui2.widgets import BusyCursor
 
+if TYPE_CHECKING:
+    from calibre.gui2.tts2.types import TTSBackend
+
 
 class Utterance(NamedTuple):
     text: str
@@ -108,12 +111,12 @@ class TTSManager(QObject):
 
     def __init__(self, parent=None):
         super().__init__(parent)
-        self._tts = None
+        self._tts: 'TTSBackend' | None = None
         self.state = QTextToSpeech.State.Ready
         self.tracker = Tracker()
 
     @property
-    def tts(self):
+    def tts(self) -> 'TTSBackend':
         if self._tts is None:
             with BusyCursor():
                 from calibre.gui2.tts2.types import create_tts_backend

src/calibre/gui2/tts2/qt.py

@@ -2,15 +2,12 @@
 # License: GPLv3 Copyright: 2024, Kovid Goyal <kovid at kovidgoyal.net>
 
 
-from qt.core import QMediaDevices, QObject, QTextToSpeech, pyqtSignal
+from qt.core import QMediaDevices, QObject, QTextToSpeech
 
-from calibre.gui2.tts2.types import EngineSpecificSettings, Voice, qvoice_to_voice
+from calibre.gui2.tts2.types import EngineSpecificSettings, TTSBackend, Voice, qvoice_to_voice
 
 
-class QtTTSBackend(QObject):
-
-    saying = pyqtSignal(int, int)
-    state_changed = pyqtSignal(QTextToSpeech.State)
+class QtTTSBackend(TTSBackend):
 
     def __init__(self, engine_name: str = '', parent: QObject|None = None):
         super().__init__(parent)
@@ -31,18 +28,6 @@ class QtTTSBackend(QObject):
     def default_output_module(self) -> str:
         return ''
 
-    def change_rate(self, steps: int = 1) -> bool:
-        current = self.tts.rate()
-        new_rate = max(-1, min(current + 0.2 * steps, 1))
-        if current == new_rate:
-            return False
-        self.tts.pause()
-        self.tts.setRate(new_rate)
-        self._current_settings = self._current_settings._replace(rate=new_rate)
-        self._current_settings.save_to_config()
-        self.tts.resume()
-        self.tts.stop(QTextToSpeech.BoundaryHint.Immediate)
-
     def pause(self) -> None:
         self.tts.pause()
 

src/calibre/gui2/tts2/types.py

@@ -7,7 +7,7 @@ from enum import Enum, auto
 from functools import lru_cache
 from typing import Literal, NamedTuple
 
-from qt.core import QLocale, QObject, QTextToSpeech, QVoice
+from qt.core import QLocale, QObject, QTextToSpeech, QVoice, pyqtSignal
 
 from calibre.constants import islinux, ismacos, iswindows
 from calibre.utils.config import JSONConfig
@@ -183,7 +183,33 @@ def default_engine_name() -> str:
     return 'speechd'
 
 
-def create_tts_backend(parent: QObject|None = None, force_engine: str | None = None):
+class TTSBackend(QObject):
+    saying = pyqtSignal(int, int)  # offset, length
+    state_changed = pyqtSignal(QTextToSpeech.State)
+    available_voices: dict[str, tuple[Voice, ...]] = {}
+    engine_name: str = ''
+    default_output_module: str = ''
+
+    def __init__(self, engine_name: str = '', parent: QObject|None = None):
+        super().__init__(parent)
+
+    def pause(self) -> None:
+        raise NotImplementedError()
+
+    def resume(self) -> None:
+        raise NotImplementedError()
+
+    def stop(self) -> None:
+        raise NotImplementedError()
+
+    def say(self, text: str) -> None:
+        raise NotImplementedError()
+
+    def error_message(self) -> str:
+        raise NotImplementedError()
+
+
+def create_tts_backend(parent: QObject|None = None, force_engine: str | None = None) -> TTSBackend:
     prefs = load_config()
     engine_name = prefs.get('engine', '') if force_engine is None else force_engine
     engine_name = engine_name or default_engine_name()
@@ -201,51 +227,5 @@ def create_tts_backend(parent: QObject|None = None, force_engine: str | None = N
     return ans
 
 
-def develop(engine_name=''):
-    # {{{
-    marked_text = [2, 'Demonstration', ' ', 16, 'of', ' ', 19, 'DOCX', ' ', 24, 'support', ' ', 32, 'in', ' ', 35, 'calibre', '\n\t', 44, 'This', ' ', 49, 'document', ' ', 58, 'demonstrates', ' ', 71, 'the', ' ', 75, 'ability', ' ', 83, 'of', ' ', 86, 'the', ' ', 90, 'calibre', ' ', 98, 'DOCX', ' ', 103, 'Input', ' ', 109, 'plugin', ' ', 116, 'to', ' ', 119, 'convert', ' ', 127, 'the', ' ', 131, 'various', ' ', 139, 'typographic', ' ', 151, 'features', ' ', 160, 'in', ' ', 163, 'a', ' ', 165, 'Microsoft', ' ', 175, 'Word', ' ', 180, '(2007', ' ', 186, 'and', ' ', 190, 'newer)', ' ', 197, 'document.', ' ', 207, 'Convert', ' ', 215, 'this', ' ', 220, 'document', ' ', 229, 'to', ' ', 232, 'a', ' ', 234, 'modern', ' ', 241, 'ebook', ' ', 247, 'format,', ' ', 255, 'such', ' ', 260, 'as', ' ', 263, 'AZW3', ' ', 268, 'for', ' ', 272, 'Kindles', ' ', 280, 'or', ' ', 283, 'EPUB', ' ', 288, 'for', ' ', 292, 'other', ' ', 298, 'ebook', ' ', 304, 'readers,', ' ', 313, 'to', ' ', 316, 'see', ' ', 320, 'it', ' ', 323, 'in', ' ', 326, 'action.', '\n\t', 335, 'There', ' ', 341, 'is', ' ', 344, 'support', ' ', 352, 'for', ' ', 356, 'images,', ' ', 364, 'tables,', ' ', 372, 'lists,', ' ', 379, 'footnotes,', ' ', 390, 'endnotes,', ' ', 400, 'links,', ' ', 407, 'dropcaps', ' ', 416, 'and', ' ', 420, 'various', ' ', 428, 'types', ' ', 434, 'of', ' ', 437, 'text', ' ', 442, 'and', ' ', 446, 'paragraph', ' ', 456, 'level', ' ', 462, 'formatting.', '\n\t', 475, 'To', ' ', 478, 'see', ' ', 482, 'the', ' ', 486, 'DOCX', ' ', 491, 'conversion', ' ', 502, 'in', ' ', 505, 'action,', ' ', 513, 'simply', ' ', 520, 'add', ' ', 524, 'this', ' ', 529, 'file', ' ', 534, 'to', ' ', 537, 'calibre', ' ', 545, 'using', ' ', 551, 'the', ' ', 555, '“Add', ' ', 560, 'Books”', ' ', 567, 'button', ' ', 574, 'and', ' ', 578, 'then', ' ', 583, 'click', ' ', 589, '“Convert”.', '  ', 601, 'Set', ' ', 605, 'the', ' ', 609, 'output', ' ', 616, 'format', ' ', 623, 'in', ' ', 626, 'the', ' ', 630, 'top', ' ', 634, 'right', ' ', 640, 'corner', ' ', 647, 'of', ' ', 650, 'the', ' ', 654, 'conversion', ' ', 665, 'dialog', ' ', 672, 'to', ' ', 675, 'EPUB', ' ', 680, 'or', ' ', 683, 'AZW3', ' ', 688, 'and', ' ', 692, 'click', ' ', 698, '“OK”.', '\n\t\xa0\n\t']  # noqa }}}
-
-    from calibre.gui2 import Application
-    app = Application([])
-    app.shutdown_signal_received.connect(lambda: app.exit(1))
-    tts = create_tts_backend(force_engine=engine_name)
-    speech_started = False
-
-    def print_saying(s, e):
-        bits = []
-        in_region = False
-        for x in marked_text:
-            if isinstance(x, int):
-                if in_region:
-                    if x >= e:
-                        break
-                else:
-                    if x == s:
-                        in_region = True
-                    elif x > e:
-                        break
-            elif in_region:
-                bits.append(x)
-        print('Saying:', repr(''.join(bits)))
-
-    import sys
-
-    def state_changed(state):
-        nonlocal speech_started
-        print('State changed:', state)
-        if state == QTextToSpeech.State.Speaking:
-            speech_started = True
-        elif state == QTextToSpeech.State.Error:
-            print(tts.error_message(), file=sys.stderr)
-            app.exit(1)
-        elif state == QTextToSpeech.State.Ready:
-            if speech_started:
-                app.quit()
-    tts.saying.connect(print_saying)
-    tts.state_changed.connect(state_changed)
-    tts.speak_marked_text(marked_text)
-    app.exec()
-
-
 if __name__ == '__main__':
     develop()