Back-end of paint something

app.py

from flask import Flask, request, render_template, make_response
from flask_bootstrap import Bootstrap

import os
import uuid
import base64

from PIL import Image
import warnings
warnings.simplefilter('error', Image.DecompressionBombWarning)

app = Flask(__name__, static_folder='imgs')
bootstrap = Bootstrap(app)


@app.route('/')
def do_get():
  return render_template('index.html')

@app.route('/saveimage', methods=['POST'])
def saveimage():
  event = request.form.to_dict()

  dir_name = 'imgs'
  img_name = uuid.uuid4().hex

  # Saving image in the 'imgs' folder temporarily. Should be deleted after a certain period of time
  if not os.path.exists(dir_name):
      os.makedirs(dir_name)
  with open(os.path.join(dir_name, '{}.jpg'.format(img_name)), 'wb') as img:
      img.write(base64.b64decode(event['image'].split(",")[1]))

  original = Image.open(os.path.join(dir_name, '{}.jpg'.format(img_name)))
  # Needs simple validation of format for security since Pillow supports various type of Images
  if(original.format != 'JPEG'):
      return make_response('Unsupported image type.', 400)

  original.thumbnail((240, 240), Image.ANTIALIAS)
  original.save(os.path.join(dir_name, '{}_240.jpg'.format(img_name)), 'JPEG')

  return make_response(img_name, 200)


if __name__ == '__main__':
  app.debug = True
  app.run()