321 lines
10 KiB
Python
321 lines
10 KiB
Python
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"""
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Displays Agg images in the browser, with interactivity
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"""
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# The WebAgg backend is divided into two modules:
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#
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# - `backend_webagg_core.py` contains code necessary to embed a WebAgg
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# plot inside of a web application, and communicate in an abstract
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# way over a web socket.
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#
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# - `backend_webagg.py` contains a concrete implementation of a basic
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# application, implemented with tornado.
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from contextlib import contextmanager
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import errno
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from io import BytesIO
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import json
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import mimetypes
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from pathlib import Path
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import random
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import sys
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import signal
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import socket
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import threading
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try:
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import tornado
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except ImportError as err:
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raise RuntimeError("The WebAgg backend requires Tornado.") from err
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import tornado.web
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import tornado.ioloop
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import tornado.websocket
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import matplotlib as mpl
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from matplotlib.backend_bases import _Backend
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from matplotlib._pylab_helpers import Gcf
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from . import backend_webagg_core as core
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from .backend_webagg_core import TimerTornado
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class ServerThread(threading.Thread):
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def run(self):
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tornado.ioloop.IOLoop.instance().start()
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webagg_server_thread = ServerThread()
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class FigureCanvasWebAgg(core.FigureCanvasWebAggCore):
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pass
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class WebAggApplication(tornado.web.Application):
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initialized = False
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started = False
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class FavIcon(tornado.web.RequestHandler):
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def get(self):
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self.set_header('Content-Type', 'image/png')
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self.write(Path(mpl.get_data_path(),
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'images/matplotlib.png').read_bytes())
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class SingleFigurePage(tornado.web.RequestHandler):
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def __init__(self, application, request, *, url_prefix='', **kwargs):
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self.url_prefix = url_prefix
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super().__init__(application, request, **kwargs)
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def get(self, fignum):
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fignum = int(fignum)
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manager = Gcf.get_fig_manager(fignum)
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ws_uri = 'ws://{req.host}{prefix}/'.format(req=self.request,
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prefix=self.url_prefix)
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self.render(
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"single_figure.html",
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prefix=self.url_prefix,
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ws_uri=ws_uri,
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fig_id=fignum,
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toolitems=core.NavigationToolbar2WebAgg.toolitems,
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canvas=manager.canvas)
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class AllFiguresPage(tornado.web.RequestHandler):
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def __init__(self, application, request, *, url_prefix='', **kwargs):
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self.url_prefix = url_prefix
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super().__init__(application, request, **kwargs)
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def get(self):
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ws_uri = 'ws://{req.host}{prefix}/'.format(req=self.request,
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prefix=self.url_prefix)
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self.render(
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"all_figures.html",
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prefix=self.url_prefix,
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ws_uri=ws_uri,
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figures=sorted(Gcf.figs.items()),
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toolitems=core.NavigationToolbar2WebAgg.toolitems)
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class MplJs(tornado.web.RequestHandler):
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def get(self):
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self.set_header('Content-Type', 'application/javascript')
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js_content = core.FigureManagerWebAgg.get_javascript()
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self.write(js_content)
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class Download(tornado.web.RequestHandler):
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def get(self, fignum, fmt):
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fignum = int(fignum)
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manager = Gcf.get_fig_manager(fignum)
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self.set_header(
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'Content-Type', mimetypes.types_map.get(fmt, 'binary'))
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buff = BytesIO()
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manager.canvas.figure.savefig(buff, format=fmt)
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self.write(buff.getvalue())
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class WebSocket(tornado.websocket.WebSocketHandler):
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supports_binary = True
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def open(self, fignum):
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self.fignum = int(fignum)
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self.manager = Gcf.get_fig_manager(self.fignum)
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self.manager.add_web_socket(self)
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if hasattr(self, 'set_nodelay'):
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self.set_nodelay(True)
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def on_close(self):
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self.manager.remove_web_socket(self)
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def on_message(self, message):
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message = json.loads(message)
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# The 'supports_binary' message is on a client-by-client
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# basis. The others affect the (shared) canvas as a
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# whole.
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if message['type'] == 'supports_binary':
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self.supports_binary = message['value']
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else:
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manager = Gcf.get_fig_manager(self.fignum)
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# It is possible for a figure to be closed,
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# but a stale figure UI is still sending messages
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# from the browser.
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if manager is not None:
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manager.handle_json(message)
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def send_json(self, content):
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self.write_message(json.dumps(content))
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def send_binary(self, blob):
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if self.supports_binary:
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self.write_message(blob, binary=True)
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else:
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data_uri = "data:image/png;base64,{0}".format(
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blob.encode('base64').replace('\n', ''))
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self.write_message(data_uri)
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def __init__(self, url_prefix=''):
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if url_prefix:
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assert url_prefix[0] == '/' and url_prefix[-1] != '/', \
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'url_prefix must start with a "/" and not end with one.'
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super().__init__(
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[
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# Static files for the CSS and JS
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(url_prefix + r'/_static/(.*)',
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tornado.web.StaticFileHandler,
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{'path': core.FigureManagerWebAgg.get_static_file_path()}),
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# Static images for the toolbar
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(url_prefix + r'/_images/(.*)',
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tornado.web.StaticFileHandler,
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{'path': Path(mpl.get_data_path(), 'images')}),
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# A Matplotlib favicon
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(url_prefix + r'/favicon.ico', self.FavIcon),
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# The page that contains all of the pieces
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(url_prefix + r'/([0-9]+)', self.SingleFigurePage,
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{'url_prefix': url_prefix}),
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# The page that contains all of the figures
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(url_prefix + r'/?', self.AllFiguresPage,
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{'url_prefix': url_prefix}),
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(url_prefix + r'/js/mpl.js', self.MplJs),
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# Sends images and events to the browser, and receives
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# events from the browser
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(url_prefix + r'/([0-9]+)/ws', self.WebSocket),
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# Handles the downloading (i.e., saving) of static images
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(url_prefix + r'/([0-9]+)/download.([a-z0-9.]+)',
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self.Download),
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],
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template_path=core.FigureManagerWebAgg.get_static_file_path())
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@classmethod
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def initialize(cls, url_prefix='', port=None, address=None):
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if cls.initialized:
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return
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# Create the class instance
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app = cls(url_prefix=url_prefix)
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cls.url_prefix = url_prefix
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# This port selection algorithm is borrowed, more or less
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# verbatim, from IPython.
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def random_ports(port, n):
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"""
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Generate a list of n random ports near the given port.
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The first 5 ports will be sequential, and the remaining n-5 will be
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randomly selected in the range [port-2*n, port+2*n].
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"""
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for i in range(min(5, n)):
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yield port + i
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for i in range(n - 5):
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yield port + random.randint(-2 * n, 2 * n)
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if address is None:
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cls.address = mpl.rcParams['webagg.address']
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else:
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cls.address = address
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cls.port = mpl.rcParams['webagg.port']
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for port in random_ports(cls.port,
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mpl.rcParams['webagg.port_retries']):
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try:
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app.listen(port, cls.address)
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except socket.error as e:
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if e.errno != errno.EADDRINUSE:
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raise
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else:
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cls.port = port
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break
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else:
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raise SystemExit(
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"The webagg server could not be started because an available "
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"port could not be found")
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cls.initialized = True
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@classmethod
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def start(cls):
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if cls.started:
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return
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"""
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IOLoop.running() was removed as of Tornado 2.4; see for example
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https://groups.google.com/forum/#!topic/python-tornado/QLMzkpQBGOY
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Thus there is no correct way to check if the loop has already been
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launched. We may end up with two concurrently running loops in that
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unlucky case with all the expected consequences.
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"""
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ioloop = tornado.ioloop.IOLoop.instance()
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def shutdown():
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ioloop.stop()
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print("Server is stopped")
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sys.stdout.flush()
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cls.started = False
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@contextmanager
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def catch_sigint():
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old_handler = signal.signal(
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signal.SIGINT,
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lambda sig, frame: ioloop.add_callback_from_signal(shutdown))
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try:
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yield
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finally:
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signal.signal(signal.SIGINT, old_handler)
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# Set the flag to True *before* blocking on ioloop.start()
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cls.started = True
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print("Press Ctrl+C to stop WebAgg server")
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sys.stdout.flush()
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with catch_sigint():
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ioloop.start()
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def ipython_inline_display(figure):
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import tornado.template
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WebAggApplication.initialize()
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if not webagg_server_thread.is_alive():
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webagg_server_thread.start()
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fignum = figure.number
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tpl = Path(core.FigureManagerWebAgg.get_static_file_path(),
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"ipython_inline_figure.html").read_text()
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t = tornado.template.Template(tpl)
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return t.generate(
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prefix=WebAggApplication.url_prefix,
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fig_id=fignum,
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toolitems=core.NavigationToolbar2WebAgg.toolitems,
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canvas=figure.canvas,
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port=WebAggApplication.port).decode('utf-8')
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@_Backend.export
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class _BackendWebAgg(_Backend):
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FigureCanvas = FigureCanvasWebAgg
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FigureManager = core.FigureManagerWebAgg
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@staticmethod
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def show():
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WebAggApplication.initialize()
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url = "http://{address}:{port}{prefix}".format(
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address=WebAggApplication.address,
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port=WebAggApplication.port,
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prefix=WebAggApplication.url_prefix)
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if mpl.rcParams['webagg.open_in_browser']:
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import webbrowser
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if not webbrowser.open(url):
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print("To view figure, visit {0}".format(url))
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else:
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print("To view figure, visit {0}".format(url))
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WebAggApplication.start()
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