Fix some import issues, and save the scale factor on the BitmapLoader class (since it probably won't be changing?)

gui/bitmap_loader.py

@@ -27,8 +27,6 @@ import wx
 
 import config
 
-import gui.mainFrame as mainFrame
-
 from logbook import Logger
 logging = Logger(__name__)
 
@@ -48,6 +46,8 @@ class BitmapLoader(object):
     dont_use_cached_bitmaps = False
     max_cached_bitmaps = 500
 
+    scaling_factor = None
+
     @classmethod
     def getStaticBitmap(cls, name, parent, location):
         static = wx.StaticBitmap(parent)
@@ -78,18 +78,23 @@ class BitmapLoader(object):
 
     @classmethod
     def loadBitmap(cls, name, location):
-        filename = "{0}.png".format(name)
-        scale = int(mainFrame.MainFrame.getInstance().GetContentScaleFactor())
-        if scale == 1:
+        if cls.scaling_factor is None:
+            import gui.mainFrame
+            cls.scaling_factor = int(gui.mainFrame.MainFrame.getInstance().GetContentScaleFactor())
+        scale = cls.scaling_factor
+        print(cls.scaling_factor)
+        filenameScaled = "{0}@{1}x.png".format(name, scale)
+        img = cls.loadImage(filenameScaled, location)
+
+        if img is None:
+            # can't find the scaled image, fallback to no scaling
+            filename = "{0}.png".format(name)
             img = cls.loadImage(filename, location)
-        else:
-            filenameScaled = "{0}@{1}x.png".format(name, scale)
-            img = cls.loadImage(filenameScaled, location)
-            if img is None:
-                img = cls.loadImage(filename, location)
-                scale = 1
+            scale = 1
+
         if img is None:
             return None
+
         bmp: wx.Bitmap = img.ConvertToBitmap()
         if scale > 1:
             bmp.SetSize((int(bmp.GetWidth()/scale), int(bmp.GetHeight()/scale)))