Allow cancelling TTS

app/src/main/java/eu/faircode/email/EntityRule.java

@@ -1315,7 +1315,7 @@ public class EntityRule {
             sb.append(context.getString(R.string.title_rule_tts_content))
                     .append(' ').append(preview);
 
-        TTSHelper.speak(context, "rule:" + message.id, sb.toString(), message.language);
+        TTSHelper.speak(context, "rule:" + message.id, sb.toString(), message.language, false);
     }
 
     private boolean onActionSnooze(Context context, EntityMessage message, JSONObject jargs) throws JSONException {

app/src/main/java/eu/faircode/email/FragmentMessages.java

@@ -3635,6 +3635,14 @@ public class FragmentMessages extends FragmentBase
         }
 
         private void onSwipeTTS(final @NonNull TupleMessageEx message) {
+            boolean tts = iProperties.getValue("tts", message.id, false);
+            iProperties.setValue("tts", message.id, !tts);
+
+            if (tts) {
+                TTSHelper.speak(getContext(), "tts:" + message.id, "", message.language, true);
+                return;
+            }
+
             Bundle args = new Bundle();
             args.putLong("id", message.id);
 
@@ -3671,7 +3679,7 @@ public class FragmentMessages extends FragmentBase
                 @Override
                 protected void onExecuted(Bundle args, String text) {
                     if (text != null)
-                        TTSHelper.speak(getContext(), "tts:" + message.id, text, message.language);
+                        TTSHelper.speak(getContext(), "tts:" + message.id, text, message.language, true);
                 }
 
                 @Override

app/src/main/java/eu/faircode/email/TTSHelper.java

@@ -41,7 +41,8 @@ public class TTSHelper {
             @NonNull final Context context,
             @NonNull final String utteranceId,
             @NonNull final String text,
-            final String language) {
+            final String language,
+            final boolean flush) {
 
         Locale locale = (language == null ? Locale.getDefault() : new Locale(language));
 
@@ -55,7 +56,7 @@ public class TTSHelper {
                             " available=" + available +
                             " utterance=" + utteranceId +
                             " text=" + text);
-                    instance.speak(text, TextToSpeech.QUEUE_ADD, null, utteranceId);
+                    instance.speak(text, flush ? TextToSpeech.QUEUE_FLUSH : TextToSpeech.QUEUE_ADD, null, utteranceId);
                 } catch (Throwable ex) {
                     Log.e(ex);
                 }