core: create qPrefLocationService from SettingsObjectWrapper

Update set/get functions to follow common name scheme:
- get function have same name as in struct prefs
- set function have set_<name>
- signal function have <name>_changed

one class one .h/.cpp is the C++ idiom. Having load/sync of each
variable in 1 functions (in contrast to the distributed way
SettingsObjectWrapper handles it) secures the same storage name
is used. Having the set/get/load/sync functions grouped together
makes it easier to get an overview.

REMARK: this commit only defines the class, it is not active in production

Signed-off-by: Jan Iversen <jani@apache.org>

core/settings/qPrefLocationService.h

@@ -0,0 +1,41 @@
+// SPDX-License-Identifier: GPL-2.0
+#ifndef QPREFLOCATIONSERVICE_H
+#define QPREFLOCATIONSERVICE_H
+#include "core/pref.h"
+
+#include <QObject>
+
+
+class qPrefLocationService : public QObject {
+	Q_OBJECT
+	Q_PROPERTY(int distance_threshold READ distance_threshold WRITE set_distance_threshold NOTIFY distance_threshold_changed);
+	Q_PROPERTY(int time_threshold READ time_threshold WRITE set_time_threshold NOTIFY time_threshold_changed);
+
+public:
+	qPrefLocationService(QObject *parent = NULL);
+	static qPrefLocationService *instance();
+
+	// Load/Sync local settings (disk) and struct preference
+	void loadSync(bool doSync);
+	void load() { loadSync(false); }
+	void sync() { loadSync(true); }
+
+public:
+	int distance_threshold() { return prefs.distance_threshold; }
+	int time_threshold() { return prefs.time_threshold; }
+
+public slots:
+	void set_distance_threshold(int value);
+	void set_time_threshold(int value);
+
+signals:
+	void distance_threshold_changed(int value);
+	void time_threshold_changed(int value);
+
+
+private:
+	void disk_distance_threshold(bool doSync);
+	void disk_time_threshold(bool doSync);
+};
+
+#endif