save settings in pickle for future sessions

buildozer.spec

@@ -85,7 +85,7 @@ fullscreen = 0
 #android.presplash_color = #FFFFFF
 
 # (list) Permissions
-android.permissions = INTERNET,ACCESS_FINE_LOCATION,ACCESS_COARSE_LOCATION,WAKE_LOCK
+android.permissions = INTERNET,ACCESS_FINE_LOCATION,ACCESS_COARSE_LOCATION,WAKE_LOCK,READ_EXTERNAL_STORAGE,WRITE_EXTERNAL_STORAGE
 
 # (int) Target Android API, should be as high as possible.
 #android.api = 27

flockompass.kv

@@ -166,7 +166,7 @@
             max: 0.99
             step: 0.05
             orientation: 'horizontal'
-            value: 0.88
+            value: app.session_data['settings_smoothing']
             on_value: app.set_smoothing()
 
         BackgroundLabel:
@@ -182,7 +182,7 @@
             max: 0.9
             step: 0.05
             orientation: 'horizontal'
-            value: 0.777
+            value: app.session_data['settings_compass_update']
             on_value: app.set_compass_update()
 
         BackgroundLabel:

main.py

@@ -15,6 +15,8 @@ from math import atan2, sin, cos, degrees, floor
 
 from geopy.distance import geodesic
 
+from os import path
+import pickle
 
 class IconButton(ButtonBehavior, Image):
     pass
@@ -63,13 +65,42 @@ class FlockompassApp(App):
     def dump(self, dt):
         print(dt, self.gps_data, self.session_data)
 
+    def read_settings(self):
+        app_folder = os.path.dirname(os.path.abspath(__file__))
+        pickle_path = path.join(app_folder, 'settings.pickle')
+
+        if path.isfile(pickle_path):
+            with open(pickle_path, 'rb') as f:
+                settings = pickle.load(f)
+        else:
+            settings = {'settings_smoothing': 0.88,
+                        'settings_compass_update': 0.777
+            }
+            with open(pickle_path, 'wb') as f:
+                pickle.dump(settings, f)
+
+        self.session_data.update(settings)
+
+    def save_settings(self):
+        app_folder = os.path.dirname(os.path.abspath(__file__))
+        pickle_path = path.join(app_folder, 'settings.pickle')
+
+        settings = {k: self.session_data[k]
+                    for k in self.session_data
+                    if k.startswith('settings_')}
+
+        with open(pickle_path, 'wb') as f:
+            pickle.dump(settings, f)
+
     def set_smoothing(self):
-        self.session_data['smoothing'] = self.ss.ids.slider_smoothing.value
+        self.session_data['settings_smoothing'] = self.ss.ids.slider_smoothing.value
+        self.save_settings()
 
     def set_compass_update(self):
-        self.session_data['compass_update'] = self.ss.ids.slider_compass_update.value
+        self.session_data['settings_compass_update'] = self.ss.ids.slider_compass_update.value
         self.compass_disable()
         self.compass_enable()
+        self.save_settings()
 
     def set_destination(self):
         self.compass_enable()
@@ -139,7 +170,7 @@ class FlockompassApp(App):
         if self.cs.facade.field != (None, None, None):
             x, y, z = self.cs.facade.field
 
-            smoothingFactor = self.session_data.get('smoothing', 0.88)
+            smoothingFactor = self.session_data.get('settings_smoothing', 0.88)
             angle = atan2(y, x)
             self.last_angle = smoothingFactor * self.last_angle  + (1 - smoothingFactor) * angle
 
@@ -182,7 +213,7 @@ class FlockompassApp(App):
     def compass_enable(self):
         self.cs.facade.enable()
         Clock.schedule_interval(self.get_field,
-                                1.0 - self.session_data.get('compass_update', 0.777))
+                                1.0 - self.session_data.get('settings_compass_update', 0.777))
 
     def compass_disable(self):
         self.cs.facade.disable()
@@ -239,4 +270,5 @@ class FlockompassApp(App):
 
 if __name__ == '__main__':
     app = FlockompassApp()
+    app.read_settings()
     app.run()