Added generic SingletonDialog class for managing a single dialog instance

Use this for the options dialog instead of the custom implementation in MainWindow.

picard/ui/__init__.py

@@ -57,6 +57,28 @@ class PreserveGeometry:
         config.persist[self.opt_name()] = self.saveGeometry()
 
 
+class SingletonDialog:
+    _instance = None
+
+    @classmethod
+    def get_instance(cls, *args, **kwargs):
+        if not cls._instance:
+            cls._instance = cls(*args, **kwargs)
+            cls._instance.finished.connect(cls._on_dialog_finished)
+        return cls._instance
+
+    @classmethod
+    def show_instance(cls, *args, **kwargs):
+        instance = cls.get_instance(*args, **kwargs)
+        instance.show()
+        instance.raise_()
+        instance.activateWindow()
+
+    @classmethod
+    def _on_dialog_finished(cls):
+        cls._instance = None
+
+
 class PicardDialog(QtWidgets.QDialog, PreserveGeometry):
 
     flags = QtCore.Qt.WindowSystemMenuHint | QtCore.Qt.WindowTitleHint | QtCore.Qt.WindowCloseButtonHint

picard/ui/mainwindow.py

@@ -164,7 +164,6 @@ class MainWindow(QtWidgets.QMainWindow, PreserveGeometry):
 
         self.log_dialog = LogView(self)
         self.history_dialog = HistoryView(self)
-        self.optionsDialog = None
 
         bottomLayout = QtWidgets.QHBoxLayout()
         bottomLayout.setContentsMargins(0, 0, 0, 0)
@@ -907,15 +906,7 @@ class MainWindow(QtWidgets.QMainWindow, PreserveGeometry):
         self.show_options("about")
 
     def show_options(self, page=None):
-        if not self.optionsDialog:
-            self.optionsDialog = OptionsDialog(page, self)
-            self.optionsDialog.finished.connect(self.on_options_closed)
-        self.optionsDialog.show()
-        self.optionsDialog.raise_()
-        self.optionsDialog.activateWindow()
-
-    def on_options_closed(self):
-        self.optionsDialog = None
+        OptionsDialog.show_instance(page, self)
 
     def show_help(self):
         webbrowser2.goto('documentation')

picard/ui/options/dialog.py

@@ -35,6 +35,7 @@ from picard.util import (
 from picard.ui import (
     HashableTreeWidgetItem,
     PicardDialog,
+    SingletonDialog,
 )
 from picard.ui.options import (  # noqa: F401 # pylint: disable=unused-import
     OptionsCheckError,
@@ -63,7 +64,7 @@ from picard.ui.options import (  # noqa: F401 # pylint: disable=unused-import
 from picard.ui.util import StandardButton
 
 
-class OptionsDialog(PicardDialog):
+class OptionsDialog(PicardDialog, SingletonDialog):
 
     autorestore = False