Allow <audio> to play without user interaction in accordance to autoplay setting

Since 2018, Chromium by default requires at least one user interaction with a page in order for sound to play. That's not what an Anki user expects.

So this commit undoes this by setting the policy accordingly if the deck's settings have autoplay set, so that files in <audio> tags (if they further have the autoplay attribute set / are jscripted accordingly) are treated the same as ones in [sound:…] elements. OFC, it's obviously not a good idea to mix both on one card.

(AnkiDroid's WebView has already been unconditionally ignoring the requirement since forever.)

qt/aqt/clayout.py

@@ -491,12 +491,14 @@ class CardLayout(QDialog):
             self.have_autoplayed = True
 
             if c.autoplay():
+                AnkiWebView.setPlaybackRequiresGesture(False)
                 if self.pform.preview_front.isChecked():
                     audio = c.question_av_tags()
                 else:
                     audio = c.answer_av_tags()
                 av_player.play_tags(audio)
             else:
+                AnkiWebView.setPlaybackRequiresGesture(True)
                 av_player.clear_queue_and_maybe_interrupt()
 
         self.updateCardNames()

qt/aqt/previewer.py

@@ -184,6 +184,7 @@ class Previewer(QDialog):
             bodyclass = theme_manager.body_classes_for_card_ord(c.ord)
 
             if c.autoplay():
+                AnkiWebView.setPlaybackRequiresGesture(False)
                 if self._show_both_sides:
                     # if we're showing both sides at once, remove any audio
                     # from the answer that's appeared on the question already
@@ -198,6 +199,7 @@ class Previewer(QDialog):
                     audio = c.answer_av_tags()
                 av_player.play_tags(audio)
             else:
+                AnkiWebView.setPlaybackRequiresGesture(True)
                 av_player.clear_queue_and_maybe_interrupt()
 
             txt = self.mw.prepare_card_text_for_display(txt)

qt/aqt/reviewer.py

@@ -23,6 +23,7 @@ from aqt.sound import av_player, getAudio, play_clicked_audio
 from aqt.theme import theme_manager
 from aqt.toolbar import BottomBar
 from aqt.utils import askUserDialog, downArrow, qtMenuShortcutWorkaround, tooltip
+from aqt.webview import AnkiWebView
 
 
 class ReviewerBottomBar:
@@ -183,10 +184,12 @@ class Reviewer:
         q = c.q()
         # play audio?
         if c.autoplay():
+            AnkiWebView.setPlaybackRequiresGesture(False)
             sounds = c.question_av_tags()
             gui_hooks.reviewer_will_play_question_sounds(c, sounds)
             av_player.play_tags(sounds)
         else:
+            AnkiWebView.setPlaybackRequiresGesture(True)
             av_player.clear_queue_and_maybe_interrupt()
             sounds = []
             gui_hooks.reviewer_will_play_question_sounds(c, sounds)

qt/aqt/webview.py

@@ -340,6 +340,12 @@ class AnkiWebView(QWebEngineView):
         newFactor = desiredScale / qtIntScale
         return max(1, newFactor)
 
+    @staticmethod
+    def setPlaybackRequiresGesture(value: bool) -> None:
+        QWebEngineSettings.globalSettings().setAttribute(
+            QWebEngineSettings.PlaybackRequiresUserGesture, value
+        )
+
     def _getQtIntScale(self, screen) -> int:
         # try to detect if Qt has scaled the screen
         # - qt will round the scale factor to a whole number, so a dpi of 125% = 1x,