UI: Add ClearSceneData to clean up all obs data

Add a central function for clearing all data: scenes, sources, widgets
such as lists that may contain source references in their sub-items,
dialogs which may contain source references.  In certain circumstances
this data must be fully released and manually freed to ensure that there
are no outstanding references to obs data (such as on shutdown, where
all data should be properly freed).

obs/window-basic-main.cpp

@@ -1919,6 +1919,48 @@ void OBSBasic::ResizePreview(uint32_t cx, uint32_t cy)
 	}
 }
 
+void OBSBasic::CloseDialogs()
+{
+	QList<QDialog*> childDialogs = this->findChildren<QDialog *>();
+	if (!childDialogs.isEmpty()) {
+		for (int i = 0; i < childDialogs.size(); ++i) {
+			childDialogs.at(i)->close();
+		}
+	}
+
+	for (QPointer<QWidget> &projector : projectors) {
+		delete projector;
+		projector.clear();
+	}
+}
+
+void OBSBasic::ClearSceneData()
+{
+	CloseDialogs();
+
+	ClearVolumeControls();
+	ClearListItems(ui->scenes);
+	ClearListItems(ui->sources);
+
+	obs_set_output_source(0, nullptr);
+	obs_set_output_source(1, nullptr);
+	obs_set_output_source(2, nullptr);
+	obs_set_output_source(3, nullptr);
+	obs_set_output_source(4, nullptr);
+	obs_set_output_source(5, nullptr);
+
+	auto cb = [](void *unused, obs_source_t *source)
+	{
+		obs_source_remove(source);
+		UNUSED_PARAMETER(unused);
+		return true;
+	};
+
+	obs_enum_sources(cb, nullptr);
+
+	sourceSceneRefs.clear();
+}
+
 void OBSBasic::closeEvent(QCloseEvent *event)
 {
 	if (outputHandler && outputHandler->Active()) {
@@ -1943,21 +1985,6 @@ void OBSBasic::closeEvent(QCloseEvent *event)
 
 	signalHandlers.clear();
 
-	/* Check all child dialogs and ensure they run their proper closeEvent
-	 * methods before exiting the application.  Otherwise Qt doesn't send
-	 * the proper QCloseEvent messages. */
-	QList<QDialog*> childDialogs = this->findChildren<QDialog *>();
-	if (!childDialogs.isEmpty()) {
-		for (int i = 0; i < childDialogs.size(); ++i) {
-			childDialogs.at(i)->close();
-		}
-	}
-
-	for (QPointer<QWidget> &projector : projectors) {
-		delete projector;
-		projector.clear();
-	}
-
 	// remove draw callback in case our drawable surfaces go away before
 	// the destructor gets called
 	obs_remove_draw_callback(OBSBasic::RenderMain, this);
@@ -1967,16 +1994,9 @@ void OBSBasic::closeEvent(QCloseEvent *event)
 	delete saveTimer;
 	SaveProject();
 
-	/* Clear the list boxes in ::closeEvent to ensure that we can process
-	 * any ->deleteLater events in this window created by Qt in relation to
-	 * their internal data */
-	ClearVolumeControls();
-
-	QListWidgetItem *item = nullptr;
-	while ((item = ui->scenes->takeItem(0)))
-		delete item;
-
-	ClearListItems(ui->sources);
+	/* Clear all scene data (dialogs, widgets, widget sub-items, scenes,
+	 * sources, etc) so that all references are released before shutdown */
+	ClearSceneData();
 }
 
 void OBSBasic::changeEvent(QEvent *event)

obs/window-basic-main.hpp

@@ -161,6 +161,9 @@ private:
 	void CreatePropertiesWindow(obs_source_t *source);
 	void CreateFiltersWindow(obs_source_t *source);
 
+	void CloseDialogs();
+	void ClearSceneData();
+
 	void Nudge(int dist, MoveDir dir);
 	void OpenProjector(obs_source_t *source, int monitor);