While developing the Dashboard module I had problems to display charts generated with Pygal. Charts can only be saved as SVG format (they can be saved as PNG files but I haven’t found any portable library to use easily in Windows).
The first solution I came up with was to create an HTML file and then point to the SVG file but WebKit doesn’t allow to do that if you aren’t using a Webserver (it is all about security policies).
So the next step was to implement a tiny webserver based on Python 3 core standard library. After a few research looking for simple implementations I found one very simple. At first, it worked but then Basico became unstable:
– After stopping Basico, the next execution returns errors due to the webserver isn’t stopped successfully and the port remains binded.
– Another issue: you can’t run the webserver and GTK application in the same thread because then the application freezes.
After a little bit more of research I was able to rewrite the module to overcome these problems and keep the compatibility in both platforms, Linux and Windows.
Finally, I was able to load my webpage from my tiny and simple webserver and embed it into my GTK application using WebKit:
The code used to do this:
#!/usr/bin/python
# -*- coding: utf-8 -*-
# File: webserver.py
# Author: Tomás Vírseda
# License: GPL v3
# Description: Simple and tiny WebServer service for Basico
import os
import time
import threading
from http.server import HTTPServer, SimpleHTTPRequestHandler
import socketserver
from .service import Service
from .env import LPATH
# FIXME: make PORT dynamic via configuration
PORT = 8763 # Custom Port. Could be any above 1024.
WEBROOT = LPATH['WWW']
class LoggingRequestHandler(SimpleHTTPRequestHandler):
'''Custom class based on SimpleHTTPRequestHandler which disables
logging
'''
def log_message(self, format, *args):
return
class WebServer(Service):
def initialize(self):
os.chdir(WEBROOT)
self.webserver = HTTPServer(('localhost', PORT), LoggingRequestHandler)
def run(self):
self.thread = threading.Thread(target = self.webserver.serve_forever)
self.thread.daemon = True
self.thread.start()
self.log.debug("Basico WebServer Document Root: %s" % WEBROOT)
self.log.debug('Basico WebServer listening on port: {}'.format(self.webserver.server_port))
def halt(self):
self.webserver.shutdown()
self.thread.join()
def finalize(self):
self.halt()
The HTML code:
<html>
<head></head>
<body>
<h1>SAP Components</h1>
<h3>Number of SAP Notes for each SAP Component in your database</h3>
<object id="svg1" data="chart.svg" type="image/svg+xml"></object>
</body>
</html>