Source Code for Module Button

  1  # Button.py 
  2   
  3  ''' 
  4  Class that represents a push button on some GPIO port. 
  5   
  6   
  7   This software is part of the raspibrickpi module. 
  8   It is Open Source Free Software, so you may 
  9   - run the code for any purpose 
 10   - study how the code works and adapt it to your needs 
 11   - integrate all or parts of the code in your own programs 
 12   - redistribute copies of the code777 
 13   - improve the code and release your improvements to the public 
 14   However the use of the code is entirely your responsibility. 
 15  ''' 
 16   
 17  import RPi.GPIO as GPIO 
 18  import time 
 19  from threading import Thread 
 20   
 21  DEBUG = False 
 22   
 23  # Button event constants 
 24  BUTTON_PRESSED = 1 
 25  BUTTON_RELEASED = 2 
 26  BUTTON_LONGPRESSED = 3 
 27  BUTTON_CLICKED = 4 
 28  BUTTON_DOUBLECLICKED = 5 
 29  BUTTON_LONGPRESS_DURATION = 2 # default (in s) the button must be pressed to be a long press 
 30  BUTTON_DOUBLECLICK_TIME = 1 # default time (in s) to wait for a double click event 
 31   
 32 -class _ClickThread(Thread): 
 33 -    def __init__(self, button): 
 34          Thread.__init__(self) 
 35          self.button = button 
 36          self.start() 
 37   
 38 -    def run(self): 
 39          if DEBUG: 
 40              print "===>ClickThread started" 
 41          self.isRunning = True 
 42          startTime = time.time() 
 43          while self.isRunning and (time.time() - startTime < BUTTON_DOUBLECLICK_TIME): 
 44              time.sleep(0.1) 
 45          if self.button.clickCount == 1 and not self.button.isLongPressEvent: 
 46              if self.button.xButtonListener != None: 
 47                  self.button.xButtonListener(self.button, BUTTON_CLICKED) 
 48              self.button.clickThread = None 
 49          self.isRunning  = False 
 50          if DEBUG: 
 51              print "===>ClickThread terminated" 
 52   
 53 -    def stop(self): 
 54          self.isRunning = False 
 55   
 56 -class _ButtonThread(Thread): 
 57 -    def __init__(self, button): 
 58          Thread.__init__(self) 
 59          self.button = button 
 60          self.isRunning = False 
 61   
 62 -    def run(self): 
 63          if DEBUG: 
 64              print "===>ButtonThread started" 
 65          self.isRunning = True 
 66          startTime = time.time() 
 67          while self.isRunning and (time.time() - startTime < BUTTON_LONGPRESS_DURATION): 
 68              time.sleep(0.1) 
 69          if self.isRunning: 
 70              if self.button.buttonListener != None: 
 71                  self.button.buttonListener(BUTTON_LONGPRESSED) 
 72          if DEBUG: 
 73              print "===>ButtonThread terminated" 
 74   
 75 -    def stop(self): 
 76          self.isRunning = False 
 77   
 78 -class Button(): 
 79      GPIO.setmode(GPIO.BOARD) 
 80      pinsEnabled = [] 
 81 -    def __init__(self, pin, enable = True): 
 82          ''' 
 83          Creates a button instance at given pin. If enable = True, the button events are immediately enabled; 
 84          otherwise they must be enabled by calling setEnable(True). 
 85          ''' 
 86          self._isButtonEnabled = enable 
 87          self.pin = pin 
 88          GPIO.setup(pin, GPIO.IN, GPIO.PUD_UP) 
 89          if not pin in Button.pinsEnabled: 
 90              GPIO.add_event_detect(pin, GPIO.BOTH, self._onButtonEvent) 
 91              Button.pinsEnabled.append(pin) 
 92          else:  
 93              GPIO.remove_event_detect(pin) 
 94              GPIO.add_event_detect(pin, GPIO.BOTH, self._onButtonEvent) 
 95          self.buttonThread = None 
 96          self.clickThread = None 
 97          self._inCallback = False 
 98   
 99 -    def addXButtonListener(self, listener): 
100          ''' 
101          Registers a listener function to get notifications when the pushbutton is pressed, released, clicked, 
102          double-clicked or long pressed. Sequences are: 
103          click: BUTTON_PRESSED, BUTTON_RELEASED, BUTTON_CLICKED 
104          double-click: BUTTON_PRESSED, BUTTON_RELEASED, BUTTON_PRESSED, BUTTON_RELEASED, BUTTON_DOUBLECLICKED 
105          long pressed: BUTTON_PRESSED, BUTTON_LONGPRESSED,  BUTTON_RELEASED 
106          @param listener: the listener function (with integer parameter event) to register. 
107          ''' 
108          self.addButtonListener(self._onXButtonEvent) 
109          self.xButtonListener = listener 
110   
111 -    def addButtonListener(self, listener): 
112          ''' 
113          Registers a listener function to get notifications when the pushbutton is pressed and released. 
114          @param listener: the listener function (with integer parameter event) to register. 
115          ''' 
116          self.buttonListener = listener 
117   
118      # Hardware callback 
119 -    def _onButtonEvent(self, channel): 
120          if not self._isButtonEnabled: 
121              return 
122          if self._inCallback: # inhibit reentrance 
123              return 
124          self._inCallback = True 
125          # switch may bounce: down-up-up, down-up-down, down-down-up etc. in fast sequence 
126          if GPIO.input(self.pin) == GPIO.LOW: 
127              if self.buttonThread == None: # down-down is suppressed 
128                  if DEBUG: 
129                      print "->ButtonDown" 
130                  self.buttonThread = _ButtonThread(self) 
131                  self.buttonThread.start() 
132                  if self.buttonListener != None: 
133                      self.buttonListener(self, BUTTON_PRESSED) 
134          else: 
135              if self.buttonThread != None: # up-up is suppressed 
136                  if DEBUG: 
137                      print "->ButtonUp" 
138                  self.buttonThread.stop() 
139                  self.buttonThread.join(200) # wait until finished 
140                  self.buttonThread = None 
141                  if self.buttonListener != None: 
142                      self.buttonListener(self, BUTTON_RELEASED) 
143          self._inCallback = False 
144   
145 -    def _onXButtonEvent(self, btn, event): 
146          if event == BUTTON_PRESSED: 
147              if self.xButtonListener != None: 
148                  self.xButtonListener(btn, BUTTON_PRESSED) 
149              self.isLongPressEvent = False 
150              if self.clickThread == None: 
151                  self.clickCount = 0 
152                  self.clickThread = _ClickThread(self) 
153       
154          elif event == BUTTON_RELEASED: 
155              if self.xButtonListener != None: 
156                  self.xButtonListener(btn, BUTTON_RELEASED) 
157              if self.isLongPressEvent and self.clickThread != None: 
158                  self.clickThread.stop() 
159                  self.clickThread = None 
160                  return 
161              if self.clickThread != None and self.clickThread.isRunning: 
162                  self.clickCount += 1 
163                  if self.clickCount == 2: 
164                      self.clickThread.stop() 
165                      self.clickThread = None 
166                      if self.xButtonListener != None: 
167                          self.xButtonListener(btn, BUTTON_DOUBLECLICKED) 
168              else: 
169                  self.clickThread = None 
170       
171          elif event == BUTTON_LONGPRESSED: 
172              self.isLongPressEvent = True 
173              if self.xButtonListener != None: 
174                  self.xButtonListener(btn, BUTTON_LONGPRESSED) 
175       
176 -    def setEnable(self, enable): 
177          ''' 
178          Enables/disables the button events. 
179          ''' 
180          self._isButtonEnabled = enable 
181