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# Embedding WebAgg

This example demonstrates how to embed matplotlib WebAgg interactive plotting in your own web application and framework. It is not necessary to do all this if you merely want to display a plot in a browser or use matplotlib’s built-in Tornado-based server “on the side”.

The framework being used must support web sockets.

    import io

    try:
        import tornado
    except ImportError:
        raise RuntimeError("This example requires tornado.")
    import tornado.web
    import tornado.httpserver
    import tornado.ioloop
    import tornado.websocket

    from matplotlib.backends.backend_webagg_core import (
        FigureManagerWebAgg, new_figure_manager_given_figure)
    from matplotlib.figure import Figure

    import numpy as np

    import json

    def create_figure():
        """
        Creates a simple example figure.
        """
        fig = Figure()
        a = fig.add_subplot(111)
        t = np.arange(0.0, 3.0, 0.01)
        s = np.sin(2 * np.pi * t)
        a.plot(t, s)
        return fig

    # The following is the content of the web page.  You would normally
    # generate this using some sort of template facility in your web
    # framework, but here we just use Python string formatting.
    html_content = """
    <html>
      <head>
        <!-- TODO: There should be a way to include all of the required javascript
                   and CSS so matplotlib can add to the set in the future if it
                   needs to. -->
        <link rel="stylesheet" href="_static/css/page.css" type="text/css">
        <link rel="stylesheet" href="_static/css/boilerplate.css" type="text/css" />
        <link rel="stylesheet" href="_static/css/fbm.css" type="text/css" />
        <link rel="stylesheet" href="_static/jquery/css/themes/base/jquery-ui.min.css" >
        <script src="_static/jquery/js/jquery-1.11.3.min.js"></script>
        <script src="_static/jquery/js/jquery-ui.min.js"></script>
        <script src="mpl.js"></script>

        <script>
          /* This is a callback that is called when the user saves
             (downloads) a file.  Its purpose is really to map from a
             figure and file format to a url in the application. */
          function ondownload(figure, format) {
            window.open('download.' + format, '_blank');
          };

          $(document).ready(
            function() {
              /* It is up to the application to provide a websocket that the figure
                 will use to communicate to the server.  This websocket object can
                 also be a "fake" websocket that underneath multiplexes messages
                 from multiple figures, if necessary. */
              var websocket_type = mpl.get_websocket_type();
              var websocket = new websocket_type("%(ws_uri)sws");

              // mpl.figure creates a new figure on the webpage.
              var fig = new mpl.figure(
                  // A unique numeric identifier for the figure
                  %(fig_id)s,
                  // A websocket object (or something that behaves like one)
                  websocket,
                  // A function called when a file type is selected for download
                  ondownload,
                  // The HTML element in which to place the figure
                  $('div#figure'));
            }
          );
        </script>

        <title>matplotlib</title>
      </head>

      <body>
        <div id="figure">
        </div>
      </body>
    </html>
    """

    class MyApplication(tornado.web.Application):
        class MainPage(tornado.web.RequestHandler):
            """
            Serves the main HTML page.
            """

            def get(self):
                manager = self.application.manager
                ws_uri = "ws://{req.host}/".format(req=self.request)
                content = html_content % {
                    "ws_uri": ws_uri, "fig_id": manager.num}
                self.write(content)

        class MplJs(tornado.web.RequestHandler):
            """
            Serves the generated matplotlib javascript file.  The content
            is dynamically generated based on which toolbar functions the
            user has defined.  Call `FigureManagerWebAgg` to get its
            content.
            """

            def get(self):
                self.set_header('Content-Type', 'application/javascript')
                js_content = FigureManagerWebAgg.get_javascript()

                self.write(js_content)

        class Download(tornado.web.RequestHandler):
            """
            Handles downloading of the figure in various file formats.
            """

            def get(self, fmt):
                manager = self.application.manager

                mimetypes = {
                    'ps': 'application/postscript',
                    'eps': 'application/postscript',
                    'pdf': 'application/pdf',
                    'svg': 'image/svg+xml',
                    'png': 'image/png',
                    'jpeg': 'image/jpeg',
                    'tif': 'image/tiff',
                    'emf': 'application/emf'
                }

                self.set_header('Content-Type', mimetypes.get(fmt, 'binary'))

                buff = io.BytesIO()
                manager.canvas.print_figure(buff, format=fmt)
                self.write(buff.getvalue())

        class WebSocket(tornado.websocket.WebSocketHandler):
            """
            A websocket for interactive communication between the plot in
            the browser and the server.

            In addition to the methods required by tornado, it is required to
            have two callback methods:

                - ``send_json(json_content)`` is called by matplotlib when
                  it needs to send json to the browser.  `json_content` is
                  a JSON tree (Python dictionary), and it is the responsibility
                  of this implementation to encode it as a string to send over
                  the socket.

                - ``send_binary(blob)`` is called to send binary image data
                  to the browser.
            """
            supports_binary = True

            def open(self):
                # Register the websocket with the FigureManager.
                manager = self.application.manager
                manager.add_web_socket(self)
                if hasattr(self, 'set_nodelay'):
                    self.set_nodelay(True)

            def on_close(self):
                # When the socket is closed, deregister the websocket with
                # the FigureManager.
                manager = self.application.manager
                manager.remove_web_socket(self)

            def on_message(self, message):
                # The 'supports_binary' message is relevant to the
                # websocket itself.  The other messages get passed along
                # to matplotlib as-is.

                # Every message has a "type" and a "figure_id".
                message = json.loads(message)
                if message['type'] == 'supports_binary':
                    self.supports_binary = message['value']
                else:
                    manager = self.application.manager
                    manager.handle_json(message)

            def send_json(self, content):
                self.write_message(json.dumps(content))

            def send_binary(self, blob):
                if self.supports_binary:
                    self.write_message(blob, binary=True)
                else:
                    data_uri = "data:image/png;base64,{0}".format(
                        blob.encode('base64').replace('\n', ''))
                    self.write_message(data_uri)

        def __init__(self, figure):
            self.figure = figure
            self.manager = new_figure_manager_given_figure(
                id(figure), figure)

            super(MyApplication, self).__init__([
                # Static files for the CSS and JS
                (r'/_static/(.*)',
                 tornado.web.StaticFileHandler,
                 {'path': FigureManagerWebAgg.get_static_file_path()}),

                # The page that contains all of the pieces
                ('/', self.MainPage),

                ('/mpl.js', self.MplJs),

                # Sends images and events to the browser, and receives
                # events from the browser
                ('/ws', self.WebSocket),

                # Handles the downloading (i.e., saving) of static images
                (r'/download.([a-z0-9.]+)', self.Download),
            ])

    if __name__ == "__main__":
        figure = create_figure()
        application = MyApplication(figure)

        http_server = tornado.httpserver.HTTPServer(application)
        http_server.listen(8080)

        print("http://127.0.0.1:8080/")
        print("Press Ctrl+C to quit")

        tornado.ioloop.IOLoop.instance().start()

Total running time of the script: ( 0 minutes 0.000 seconds)

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