implement loading as kivy animation rather as gif

buildozer.spec

@@ -37,7 +37,7 @@ version.filename = tools/constants.py
 
 # (list) Application requirements
 # comma separated e.g. requirements = sqlite3,kivy
-requirements = python3, kivy, Pillow, olefile
+requirements = python3, kivy
 
 # (str) Custom source folders for requirements
 # Sets custom source for any requirements with recipes

screens/custom_widgets/popup/loading_popup.kv

@@ -17,11 +17,22 @@
             color: (0,0,0,1)
             halign: "center"
             valign: "middle"
-
-        Image:
-            id: loading_image
-            size_hint: (0.8,0.7)
-            pos_hint: {"center_x":0.5,"center_y":0.6}
-            fit_mode: "contain"
-            source: PATH_IMAGES + "loading.gif"
-            anim_delay: 0.04
+
+        RelativeLayout:
+            size_hint: (0.7, 0.6)
+            pos_hint: {"center_x":0.5, "center_y": 0.6}
+
+            canvas.before:
+                PushMatrix
+                Rotate:
+                    angle: root.angle
+                    axis: 0, 0, 1
+                    origin: self.width/2, self.height/2
+            canvas.after:
+                PopMatrix
+
+            Image:
+                id: loading_image
+                source: PATH_IMAGES + "loading.png"
+                size_hint: (1, 1)
+                pos_hint: {'center_x': 0.5, "center_y": 0.5}

screens/custom_widgets/popup/loading_popup.py

@@ -10,9 +10,10 @@
 ### Kivy imports ###
 
 from kivy.properties import (
-    ObjectProperty,
+    NumericProperty,
     StringProperty
 )
+from kivy.animation import Animation, AnimationTransition
 
 ### Local imports ###
 
@@ -28,8 +29,25 @@ class LoadingPopup(CustomPopup):
 
     title = StringProperty()
     center_text = StringProperty()
+    angle = NumericProperty(0)
 
     def __init__(self, **kwargs):
         super().__init__(**kwargs)
         self.center_text = "Loading in progress..."
         self.title = "Loading"
+
+        anim1 = Animation(angle=360, duration=2,
+                          t=AnimationTransition.linear)
+        anim2 = Animation(angle=360, duration=2,
+                          t=AnimationTransition.linear)
+        self.sequence = anim1 + anim2
+        self.sequence.repeat = True
+        self.sequence.start(self)
+
+    def on_dismiss(self):
+        self.sequence.stop(self)
+        return super().on_dismiss()
+
+    def on_angle(self, item, angle):
+        if angle >= 360:
+            item.angle = angle - 360