globals.py

from kivy.base import Builder
from kivy.config import ConfigParser
from models import settings_file
from datetime import datetime, timedelta

Builder.load_file('base.kv')
settings = ConfigParser()
settings.read(settings_file)
if settings.sections() == []:
    settings['SETTINGS'] = {'stage': "Time Control In",
                            'day': '1',
                            'stg_no': '1',
                            'use_ll': 'True',
                            'up_count': '0',
                            'use_rt': 'True'}
    settings.write()

# Backwards Compatibility
if 'use_ll' not in settings.options('SETTINGS'):
    settings['SETTINGS']['use_ll'] = 'True'
    settings.write()

if 'offset' not in settings.options('SETTINGS'):
    settings['SETTINGS']['offset'] = '0'
    settings.write()

if 'up_count' not in settings.options('SETTINGS'):
    settings['SETTINGS']['up_count'] = '0'
    settings.write()

if 'use_rt' not in settings.options('SETTINGS'):
    settings['SETTINGS']['use_rt'] = 'True'
    settings.write()


offset = settings.getfloat('SETTINGS','offset')
prev_offset = 0 # offset due to the addition of timedelta object (see update_clock function)
update_objs = list() # list of objects which contain a clock or code involving clock
synced_time = datetime(1,1,1,1,1,1) # Time object synced with NTP server

def update_clock(dt):
    '''Adds an offset to the local time to sync it to the NTP server'''

    global prev_offset,offset,synced_time,update_objs
    t1 = datetime.now()
    synced_time = datetime.now() + timedelta(seconds=offset,microseconds=prev_offset)
    t2 = datetime.now()

    # when the timedelta object is added, the process can take some time(in microseconds order)
    # and hence a lag occurs in the time (even if very little)
    # Further accumulation of this delay can offset the time by seconds, or even minutes
    # To counteract this, the previous offset is saved which is added on the next run
    # An offset is still there as adding on the same run will make it kind of like a paradox as
    # then there will be another offset and so on
    prev_offset = (t2 - t1).microseconds
    for obj in update_objs:
        obj.tm = synced_time.time()