wrote FixedLayout kivy class

fixedlayout.py

@@ -0,0 +1,59 @@
+from kivy.uix.scatterlayout import ScatterLayout
+from kivy.properties import ObjectProperty
+from kivy.core.window import Window
+
+class FixedLayout(ScatterLayout):
+
+    screensize = ObjectProperty((1920, 1080))
+
+    def __init__(self, **kw):
+        kw['size'] = (Window.width, Window.height)
+        kw['size_hint'] = (None, None)
+        kw['do_scale'] = False
+        kw['do_translation'] = False
+        kw['do_rotation'] = False
+        super(FixedLayout, self).__init__(**kw)
+        self.init_diff = [
+            self.screensize[0]-Window.width,
+            self.screensize[1]-Window.height
+        ]
+        self.__fit_to_window()
+        Window.bind(system_size=self.__fit_to_window)
+
+    def __fit_to_window(self, *args):
+        window_ratio = Window.width/float(Window.height)
+        if window_ratio>1:
+            self.__fit_to_landscape_window()
+        else:
+            self.__fit_to_portrait_window()
+
+
+    def __fit_to_landscape_window(self, *args):
+        self.rotation = 0
+        screen_ratio = self.screensize[0]/float(self.screensize[1])
+        window_ratio = Window.width/float(Window.height)
+        if screen_ratio > window_ratio:
+            self.scale = Window.width/float(self.screensize[0])
+        else:
+            self.scale = Window.height/float(self.screensize[1])
+        frame_left = (self.init_diff[0]/2)*self.scale
+        frame_bottom = (self.init_diff[1]/2)*self.scale
+        self.center = (
+            Window.width/2-frame_left,
+            Window.height/2-frame_bottom
+        )
+
+    def __fit_to_portrait_window(self, *args):
+        self.rotation = -90
+        screen_ratio = self.screensize[1]/float(self.screensize[0])
+        window_ratio = Window.width/float(Window.height)
+        if screen_ratio > window_ratio:
+            self.scale = Window.width/float(self.screensize[1])
+        else:
+            self.scale = Window.height/float(self.screensize[0])
+        frame_left = (self.init_diff[1]/2)*self.scale
+        frame_bottom = (self.init_diff[0]/2)*self.scale
+        self.center = (
+            Window.width/2-frame_left,
+            Window.height/2+frame_bottom
+        )

main.py

@@ -5,6 +5,8 @@
 from kivy.uix.screenmanager import ScreenManager, Screen, FadeTransition
 from kivy.uix.widget import Widget 
 
+from fixedlayout import FixedLayout
+
 __version__ = '0.0.1'
 
 class GameScreen(Screen):

mancala.kv

@@ -6,16 +6,16 @@ MancalaScreenManagement:
 
 <GameScreen>
     name: "game_screen"
-    RelativeLayout:
+    FixedLayout:
         canvas:
             Rectangle:
                 source: 'assets/img/birch-game-board.png'
-                pos: self.pos
-                size: self.size
+                pos: (0, 0)
+                size: (1920, 1080)
 
 <SettingsScreen>
     name: "settings_screen"
-    RelativeLayout:
+    FixedLayout:
         canvas:
             Rectangle:
                 source: 'assets/img/settings.png'