How to quit the program in while loop using push-button in PyQt

Question

I have the following code which will start after clicking the \'Start\' button in PyQt:

def Start(self):
  import time
  import os
  import RPi.GPIO as GPIO
         


        

Answer 1

1. This question is useful: tkinter loop and serial write It could be copied over with two changes: master.update becomes QtGui.qApp.processEvents and master.after becomes QTimer.singleShot.

2. Here is a sketch of how to do what you ask for with guiLoop:

   from guiLoop import guiLoop, stopLoop
   # ... means fill in your code
   class ...: 
       started = False
   
       def Start(self):
           if not self.started:
               # you can also use threads here, see the first link
               self.started = self.StartLoop()
   
       def Stop(self):
           if self.started:
               stopLoop(self.started)
               self.started = False
   
       @guiLoop
       def StartLoop(self):
           # This is your Start function
           # ...
           while True:
               # ...
               yield 0.085 # time.sleep(0.085) equivalent
               # ...
   

   Since I do not know what your code look like, here is a working example using PyQT4 and guiLoop:

   from PyQt4 import QtGui
   import sys
   
   from guiLoop import guiLoop # https://gist.github.com/niccokunzmann/8673951
   
   @guiLoop
   def led_blink(argument):
       while 1:
           print("LED on " + argument)
           yield 0.5 # time to wait
           print("LED off " + argument)
           yield 0.5
   
   app = QtGui.QApplication(sys.argv)
   
   w = QtGui.QWidget()
   w.resize(250, 150)
   w.move(300, 300)
   w.setWindowTitle('Simple')
   w.show()
   
   led_blink(w, 'shiny!')
   
   sys.exit(app.exec_())
   

   guiLoop uses QTimer.singleShot(time, function) to make the loop continue.

   You can also stop the loop with stopLoop() of guiLoop.