evdev non-blocking read_one mode

foobarpay/scanner.py

@@ -50,7 +50,9 @@ class EvdevScanner(object):
         self.device.grab()
 
     def read(self):
-        for event in self.device.read_loop():
+        for event in self.device.read_one():
+            if not event:
+                return None
             if event.type != ecodes.EV_KEY or event.value != 1:
                 return None
             scanned_input = self.scancodes.get(event.code)