Py-script for reading a file and displaying the text with the Raspberry scroll pHAT

scroll.py

#!/usr/bin/env python

### http://docs.pimoroni.com/scrollphat

from collections import namedtuple
import json
import os
import sys
import time

import scrollphat


BRIGHTNESS = 10
FILENAME = './scroll.json'
FLASH_BRIGHTNESS = 150
MESSAGE = 'GO TEAM'


message = MESSAGE


class JsonFile(object):
        @staticmethod
        def _json_object_hook(d):
                return namedtuple('X', d.keys())(*d.values())


        def __init__(self, filename):
                self.content = {}
                self.timestamp = 0
                self.filename = filename
                self.read()

        def _get_timestamp(self):
                return os.stat(self.filename).st_mtime

        def has_changed(self):
                timestamp = self._get_timestamp()
                return self.timestamp != timestamp

        def read(self):
                self.timestamp = self._get_timestamp()
                try:
                        with open(FILENAME) as file:
                                self.content = json.loads(file.read(), object_hook=JsonFile._json_object_hook)
                        return True
                except ex:
                        print ex
                        return False




def main():
        global message
        scrollphat.set_brightness(BRIGHTNESS)
        file = JsonFile(FILENAME)

        while True:
                try:
                        if file.has_changed():
                                file.read()
                                flash_screen()
                        scroll_text(file.content.message, 0.1)
                except KeyboardInterrupt:
                        scrollphat.clear()
                        sys.exit(-1)



def json2obj(data):
        return json.loads(data, object_hook=_json_object_hook)


def load_json_file():
        try:
                with open(FILENAME) as data_file:
                        content = json2obj(data_file.read())
                return content
        except ex:
                print ex
                return None



def read_file(default_text):
        try:
                with open(FILENAME) as data_file:
                        content = json.load(data_file)

                return content['message']
        except:
                return default_text


def flash_screen():
        scrollphat.set_brightness(FLASH_BRIGHTNESS)
        scrollphat.set_pixels(lambda x, y: True, True)
        time.sleep(0.15)
        scrollphat.set_pixels(lambda x, y: False, True)
        time.sleep(0.15)
        scrollphat.set_pixels(lambda x, y: True, True)
        time.sleep(0.15)
        scrollphat.set_pixels(lambda x, y: False, True)
        scrollphat.set_brightness(BRIGHTNESS)


def scroll_text(text, sleep_sec):
        scrollphat.clear_buffer()
        scrollphat.write_string(text, 11)
        len = scrollphat.buffer_len()
        while len > 0:
                len -= 1
                scrollphat.scroll()
                time.sleep(sleep_sec)

if __name__ == "__main__":
        main()