deviceInfo.py

import sys                                    # import sys
import json
import time
import os
picdir = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'pic')
libdir = os.path.join(os.path.dirname(os.path.realpath(__file__)), 'lib')
if os.path.exists(libdir):
    sys.path.append(libdir)

from watchdog.observers import Observer
from watchdog.events import PatternMatchingEventHandler
from signal import pause
from waveshare_epd import epd2in7             # import the display drivers
from PIL import Image,ImageDraw,ImageFont     # import the image libraries
import time                                      
from gpiozero import Button                   # import the Button control from gpiozero

btn1 = Button(5)                              # assign each button to a variable
btn2 = Button(6)                              # by passing in the pin number
btn3 = Button(13)                             # associated with the button
btn4 = Button(19)                             # 

epd = epd2in7.EPD()                          # get the display object and assing to epd
epd.init()                                    # initialize the display
print("Clear...")                             # print message to console (not display) for debugging
epd.Clear(0xFF)                               # clear the display

deviceInfoFilePath = '/tmp/devicelist.json'
deviceInfo = {}
selectionNum = 0

class DeviceFileChange(PatternMatchingEventHandler):
    patterns=["*.json"]
    def on_modified(self, event):
        for attempt in range(3):
            try:
                with open(deviceInfoFilePath) as f:
                    newDeviceInfo = json.load(f)
                    current = json.dumps(newDeviceInfo, sort_keys=True, indent=2)
                    new = json.dumps(deviceInfo, sort_keys=True, indent=2)
                    if (current != new):
                        deviceInfo = newDeviceInfo
                        printToDisplay()
            except:
                time.sleep(0.5)
            else:
                break
        
# Listen to the file change, refresh the display accordingly.
observer = Observer()
observer.schedule(DeviceFileChange(), '/tmp/', recursive=False)
observer.start()

# Print device object to the screen
def printToDisplay():    
    LBlackImage = Image.new('1', (epd2in7.EPD_WIDTH, epd2in7.EPD_HEIGHT), 255)
    draw = ImageDraw.Draw(LBlackImage)
    font = ImageFont.truetype(os.path.join(picdir, 'Font.ttc'), 18)

    # Print the selection box
    draw.rectangle((1, 1 + selectionNum*20, 19, 19 + selectionNum*20), outline = 0)

    n = 0
    for device in deviceInfo.values():
        if (device['status']):
            # This device has been turned on
            draw.chord((5, 5 + n*20, 15, 15 + n*20), 0, 360, fill = 0)
        draw.text((20, n*20), device['name'], font = font, fill = 0)
        n += 1
    
    epd.display(epd.getbuffer(LBlackImage))
    
def writeToFile():
    with open(deviceInfoFilePath, 'w') as f:
        json.dump(deviceInfo, f)

def moveup(btn):
    global selectionNum
    if selectionNum < 12:
        selectionNum += 1
    printToDisplay()

def movedown(btn):
    global selectionNum
    if selectionNum > 0:
        selectionNum -= 1
    printToDisplay()

def turnOn(btn):
    global deviceInfo
    key = deviceInfo.keys()[selectionNum]
    if(not deviceInfo[key]['status']):
        deviceInfo[key]['status'] = True
        printToDisplay()
        writeToFile()

def turnOff(btn):
    global deviceInfo
    key = deviceInfo.keys()[selectionNum]
    if(deviceInfo[key]['status']):
        deviceInfo[key]['status'] = False
        printToDisplay()
        writeToFile()
    
# Initialize the screen
for attempt in range(3):
    try: 
        with open(deviceInfoFilePath) as f:
            deviceInfo = json.load(f)
            printToDisplay()
    except:
        time.sleep(2)
    else:
        break;
    

# tell the button what to do when pressed
btn1.when_pressed = movedown
btn2.when_pressed = moveup
btn3.when_pressed = turnOn
btn4.when_pressed = turnOff

pause()