【发布时间】：2021-03-30 02:39:23
【问题描述】：
我试图通过 Tornado 将 matplotlib 嵌入到网页中（matplotlib 后端需要）。它正在绘制一些圆圈，但拖放功能不起作用，并且 webagg 核心后端可能不支持 blitting。我发现了这个问题，因为事件没有被触发。我还没有找到使它工作的解决方案。请看以下代码：
import json
import mimetypes
from pathlib import Path
try:
import tornado
except ImportError as err:
raise RuntimeError("This example requires tornado.") from err
import tornado.web
import tornado.httpserver
import tornado.ioloop
import tornado.websocket
import matplotlib as mpl
from matplotlib.backends.backend_webagg_core import (
FigureManagerWebAgg, new_figure_manager_given_figure)
from matplotlib.figure import Figure
import numpy as np
import matplotlib.pyplot as plt
import matplotlib.patches as patches
def create_figure():
fig = plt.figure()
ax = fig.add_subplot(111)
drs = []
circles = [patches.Circle((0.32, 0.3), 0.03, fc='r', alpha=0.5),
patches.Circle((0.2, 0.35), 0.03, fc='g', alpha=0.5),
patches.Circle((0.1, 0.3), 0.03, fc='y', alpha=0.5),
patches.Circle((0.4, 0.4), 0.03, fc='r', alpha=0.5),
patches.Circle((0.3, 0.1), 0.03, fc='g', alpha=0.5)]
for circ in circles:
ax.add_patch(circ)
dr = DraggablePoint(circ)
dr.connect()
drs.append(dr)
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/css/mpl.css" type="text/css">
<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');
};
function ready(fn) {
if (document.readyState != "loading") {
fn();
} else {
document.addEventListener("DOMContentLoaded", fn);
}
}
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
document.getElementById("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
self.set_header(
'Content-Type', mimetypes.types_map.get(fmt, 'binary'))
buff = io.BytesIO()
manager.canvas.figure.savefig(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().__init__([
# Static files for the CSS and JS
(r'/_static/(.*)',
tornado.web.StaticFileHandler,
{'path': FigureManagerWebAgg.get_static_file_path()}),
# Static images for the toolbar
(r'/_images/(.*)',
tornado.web.StaticFileHandler,
{'path': Path(mpl.get_data_path(), 'images')}),
# 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),
])
class DraggablePoint:
lock = None #only one can be animated at a time
def __init__(self, point):
self.point = point
self.press = None
cv = self.point.figure.canvas
self.background = cv.copy_from_bbox(cv.figure.bbox)
def connect(self):
'connect to all the events we need'
self.cidpress = self.point.figure.canvas.mpl_connect('button_press_event', self.on_press)
self.cidrelease = self.point.figure.canvas.mpl_connect('button_release_event', self.on_release)
self.cidmotion = self.point.figure.canvas.mpl_connect('motion_notify_event', self.on_motion)
def on_press(self, event):
print('on press...')
if event.inaxes != self.point.axes: return
if DraggablePoint.lock is not None: return
contains, attrd = self.point.contains(event)
if not contains: return
self.press = (self.point.center), event.xdata, event.ydata
DraggablePoint.lock = self
# # draw everything but the selected rectangle and store the pixel buffer
# canvas = self.point.figure.canvas
# axes = self.point.axes
# self.point.set_animated(True)
# canvas.draw()
# self.background = canvas.copy_from_bbox(self.point.axes.bbox)
# # now redraw just the rectangle
# axes.draw_artist(self.point)
# # and blit just the redrawn area
# canvas.blit(axes.bbox)
def on_motion(self, event):
if DraggablePoint.lock is not self:
return
if event.inaxes != self.point.axes: return
self.point.center, xpress, ypress = self.press
dx = event.xdata - xpress
dy = event.ydata - ypress
self.point.center = (self.point.center[0]+dx, self.point.center[1]+dy)
canvas = self.point.figure.canvas
axes = self.point.axes
# restore the background region
canvas.restore_region(self.background)
# redraw just the current rectangle
axes.draw_artist(self.point)
# blit just the redrawn area
canvas.blit(axes.bbox)
def on_release(self, event):
'on release we reset the press data'
if DraggablePoint.lock is not self:
return
self.press = None
DraggablePoint.lock = None
# turn off the rect animation property and reset the background
# self.point.set_animated(False)
# self.background = None
# redraw the full figure
# self.point.figure.canvas.draw()
def disconnect(self):
'disconnect all the stored connection ids'
self.point.figure.canvas.mpl_disconnect(self.cidpress)
self.point.figure.canvas.mpl_disconnect(self.cidrelease)
self.point.figure.canvas.mpl_disconnect(self.cidmotion)
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()
【问题讨论】：
标签： python matplotlib tornado