2016-12-21 37 views
0

我得到了一個帶有主GUI線程和RFID線程的kivy應用程序(一個從設備讀取並將作業放到Queue()的守護程序線程)。查詢隊列()的時鐘由任何傳入作業設置。 GUI在後臺有一個圖像,無論何時在隊列中找到作業,所有小部件都被清除,圖像被添加到小部件,然後在兩秒後清除,循環繼續。插入卡後kivy在raspery pi上的行爲導致屏幕變白

class MainScreen(Screen): 
    background = BACKGROUND 
    def __init__(self): 
     super(MainScreen, self).__init__() 
     # Checking for cart input 30 times per second 
     self.event = Clock.schedule_interval(self.listen_for_cart_input, EVENT_INTERVAL_RATE) 
     self.add_widget(Image(source=self.background)) 

    def listen_for_cart_input(self, dt): 
     try: 
      code = carts.get(timeout=QUEUE_TIMEOUT) 
      Clock.unschedule(self.event) 
      # Do Something 
      self.handle_transition() 
     except (Empty, AssertionError): 
      pass 
    def handle_transition(self): 
     trigger_back_to_main = Clock.create_trigger(self.back_to_main, timeout=TRANSITION_TIMEOUT) 
     self.clear_widgets() 
     self.add_widget(Image(source=image)) 
     trigger_back_to_main() 

    def back_to_main(self, dt): 
     self.clear_widgets() 
     self.add_widget(Image(source=self.background)) 
     self.event = Clock.schedule_interval(self.listen_for_cart_input, EVENT_INTERVAL_RATE) 

它完美但一天幾次(每天卡插入情況〜100倍),屏幕變爲空白籌集以下異常。請注意,只有屏幕變黑並且應用程序運行正常。插入卡多次後,屏幕會再次顯示圖像。

它是一個錯誤? 我不能找出所述凸起execption

[WARNING   ] stderr: Exception in thread Thread-3: 
[WARNING   ] stderr: File "/usr/local/lib/python3.5/threading.py", line 914, in _bootstrap_inner 
[WARNING   ] stderr:  self.run() 
[WARNING   ] stderr: File "/usr/local/lib/python3.5/threading.py", line 862, in run 
[WARNING   ] stderr:  self._target(*self._args, **self._kwargs) 
[WARNING   ] stderr: File "/usr/local/lib/python3.5/site-packages/kivy/input/providers/hidinput.py", line 687, in _thread_run 
[WARNING   ] stderr:  data = fd.read(struct_input_event_sz) 
[WARNING   ] stderr: OSError: [Errno 19] No such device 

回答

0

的問題涉及到所連接的覆盆子PI到LCD HDMI電纜的原因。我通過更換電纜來修復它。

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