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"""Base Widget class. Allows user to create widgets in the backend that render
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in the IPython notebook frontend.
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"""
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#-----------------------------------------------------------------------------
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# Copyright (c) 2013, the IPython Development Team.
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#
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# Distributed under the terms of the Modified BSD License.
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#
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# The full license is in the file COPYING.txt, distributed with this software.
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#-----------------------------------------------------------------------------
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#-----------------------------------------------------------------------------
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# Imports
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#-----------------------------------------------------------------------------
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from copy import copy
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from glob import glob
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import uuid
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import sys
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import os
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import inspect
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import types
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import IPython
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from IPython.kernel.comm import Comm
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from IPython.config import LoggingConfigurable
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from IPython.utils.traitlets import Unicode, Dict, List, Instance, Bool
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from IPython.display import Javascript, display
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from IPython.utils.py3compat import string_types
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#-----------------------------------------------------------------------------
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# Classes
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#-----------------------------------------------------------------------------
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class BaseWidget(LoggingConfigurable):
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# Shared declarations (Class level)
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widget_construction_callback = None
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keys = ['default_view_name']
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def on_widget_constructed(callback):
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"""Class method, registers a callback to be called when a widget is
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constructed. The callback must have the following signature:
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callback(widget)"""
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BaseWidget.widget_construction_callback = callback
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def _handle_widget_constructed(widget):
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"""Class method, called when a widget is constructed."""
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if BaseWidget.widget_construction_callback is not None and callable(BaseWidget.widget_construction_callback):
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BaseWidget.widget_construction_callback(widget)
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# Public declarations (Instance level)
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target_name = Unicode('widget', help="""Name of the backbone model
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registered in the frontend to create and sync this widget with.""")
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default_view_name = Unicode(help="""Default view registered in the frontend
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to use to represent the widget.""")
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# Private/protected declarations
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# todo: change this to a context manager
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_property_lock = (None, None) # Last updated (key, value) from the front-end. Prevents echo.
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_displayed = False
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_comm = Instance('IPython.kernel.comm.Comm')
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def __init__(self, **kwargs):
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"""Public constructor
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"""
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self._display_callbacks = []
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self._msg_callbacks = []
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super(BaseWidget, self).__init__(**kwargs)
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self.on_trait_change(self._handle_property_changed, self.keys)
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BaseWidget._handle_widget_constructed(self)
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def __del__(self):
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"""Object disposal"""
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self.close()
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def close(self):
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"""Close method. Closes the widget which closes the underlying comm.
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When the comm is closed, all of the widget views are automatically
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removed from the frontend."""
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self._close_communication()
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@property
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def comm(self):
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if self._comm is None:
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self._open_communication()
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return self._comm
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@property
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def model_id(self):
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return self.comm.comm_id
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# Event handlers
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def _handle_msg(self, msg):
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"""Called when a msg is recieved from the frontend"""
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data = msg['content']['data']
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method = data['method']
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# Handle backbone sync methods CREATE, PATCH, and UPDATE all in one.
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if method == 'backbone' and 'sync_data' in data:
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sync_data = data['sync_data']
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self._handle_recieve_state(sync_data) # handles all methods
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# Handle a custom msg from the front-end
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elif method == 'custom':
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if 'custom_content' in data:
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self._handle_custom_msg(data['custom_content'])
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def _handle_custom_msg(self, content):
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"""Called when a custom msg is recieved."""
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for handler in self._msg_callbacks:
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if callable(handler):
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argspec = inspect.getargspec(handler)
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nargs = len(argspec[0])
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# Bound methods have an additional 'self' argument
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if isinstance(handler, types.MethodType):
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nargs -= 1
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# Call the callback
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if nargs == 1:
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handler(content)
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elif nargs == 2:
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handler(self, content)
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else:
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raise TypeError('Widget msg callback must ' \
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'accept 1 or 2 arguments, not %d.' % nargs)
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def _handle_recieve_state(self, sync_data):
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"""Called when a state is recieved from the frontend."""
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for name in self.keys:
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if name in sync_data:
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try:
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self._property_lock = (name, sync_data[name])
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setattr(self, name, sync_data[name])
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finally:
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self._property_lock = (None, None)
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def _handle_property_changed(self, name, old, new):
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"""Called when a property has been changed."""
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# Make sure this isn't information that the front-end just sent us.
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if self._property_lock[0] != name and self._property_lock[1] != new:
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# Send new state to frontend
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self.send_state(key=name)
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def _handle_displayed(self, **kwargs):
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"""Called when a view has been displayed for this widget instance
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Parameters
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----------
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[view_name]: unicode (optional kwarg)
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Name of the view that was displayed."""
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for handler in self._display_callbacks:
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if callable(handler):
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argspec = inspect.getargspec(handler)
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nargs = len(argspec[0])
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# Bound methods have an additional 'self' argument
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if isinstance(handler, types.MethodType):
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nargs -= 1
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# Call the callback
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if nargs == 0:
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handler()
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elif nargs == 1:
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handler(self)
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elif nargs == 2:
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handler(self, kwargs.get('view_name', None))
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else:
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handler(self, **kwargs)
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# Public methods
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def send_state(self, key=None):
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"""Sends the widget state, or a piece of it, to the frontend.
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Parameters
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----------
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key : unicode (optional)
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A single property's name to sync with the frontend.
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"""
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self._send({"method": "update",
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"state": self.get_state()})
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def get_state(self, key=None):
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"""Gets the widget state, or a piece of it.
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Parameters
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----------
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key : unicode (optional)
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A single property's name to get.
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"""
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state = {}
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# If a key is provided, just send the state of that key.
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if key is None:
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keys = self.keys[:]
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else:
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keys = [key]
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for k in keys:
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value = getattr(self, k)
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# a more elegant solution to encoding BaseWidgets would be
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# to tap into the JSON encoder and teach it how to deal
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# with BaseWidget objects, or maybe just teach the JSON
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# encoder to look for a _repr_json property before giving
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# up encoding
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if isinstance(value, BaseWidget):
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value = value.model_id
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elif isinstance(value, list) and len(value)>0 and isinstance(value[0], BaseWidget):
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# assume all elements of the list are widgets
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value = [i.model_id for i in value]
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state[k] = value
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return state
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def send(self, content):
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"""Sends a custom msg to the widget model in the front-end.
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Parameters
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----------
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content : dict
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Content of the message to send.
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"""
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self._send({"method": "custom",
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"custom_content": content})
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def on_msg(self, callback, remove=False):
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"""Register a callback for when a custom msg is recieved from the front-end
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Parameters
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----------
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callback: method handler
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Can have a signature of:
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- callback(content)
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- callback(sender, content)
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remove: bool
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True if the callback should be unregistered."""
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if remove and callback in self._msg_callbacks:
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self._msg_callbacks.remove(callback)
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elif not remove and not callback in self._msg_callbacks:
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self._msg_callbacks.append(callback)
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def on_displayed(self, callback, remove=False):
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"""Register a callback to be called when the widget has been displayed
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Parameters
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----------
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callback: method handler
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Can have a signature of:
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- callback()
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- callback(sender)
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- callback(sender, view_name)
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- callback(sender, **kwargs)
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kwargs from display call passed through without modification.
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remove: bool
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True if the callback should be unregistered."""
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if remove and callback in self._display_callbacks:
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self._display_callbacks.remove(callback)
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elif not remove and not callback in self._display_callbacks:
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self._display_callbacks.append(callback)
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# Support methods
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def _repr_widget_(self, **kwargs):
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"""Function that is called when `IPython.display.display` is called on
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the widget.
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Parameters
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----------
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view_name: unicode (optional)
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View to display in the frontend. Overrides default_view_name."""
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view_name = kwargs.get('view_name', self.default_view_name)
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# Create a communication.
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self._open_communication()
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# Make sure model is syncronized
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self.send_state()
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# Show view.
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self._send({"method": "display", "view_name": view_name})
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self._displayed = True
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self._handle_displayed(**kwargs)
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def _open_communication(self):
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"""Opens a communication with the front-end."""
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# Create a comm.
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if self._comm is None:
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self._comm = Comm(target_name=self.target_name)
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self._comm.on_msg(self._handle_msg)
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self._comm.on_close(self._close_communication)
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# first update
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self.send_state()
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def _close_communication(self):
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"""Closes a communication with the front-end."""
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if self._comm is not None:
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try:
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self._comm.close()
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finally:
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self._comm = None
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def _send(self, msg):
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"""Sends a message to the model in the front-end"""
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if self._comm is not None:
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self._comm.send(msg)
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return True
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else:
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return False
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class Widget(BaseWidget):
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visible = Bool(True, help="Whether or not the widget is visible.")
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# Private/protected declarations
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_css = Dict() # Internal CSS property dict
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keys = ['visible', '_css'] + BaseWidget.keys
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def get_css(self, key, selector=""):
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"""Get a CSS property of the widget. Note, this function does not
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actually request the CSS from the front-end; Only properties that have
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been set with set_css can be read.
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Parameters
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----------
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key: unicode
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CSS key
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selector: unicode (optional)
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JQuery selector used when the CSS key/value was set.
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"""
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if selector in self._css and key in self._css[selector]:
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return self._css[selector][key]
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else:
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return None
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def set_css(self, *args, **kwargs):
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"""Set one or more CSS properties of the widget (shared among all of the
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views). This function has two signatures:
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- set_css(css_dict, [selector=''])
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- set_css(key, value, [selector=''])
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Parameters
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----------
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css_dict : dict
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CSS key/value pairs to apply
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key: unicode
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CSS key
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value
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CSS value
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selector: unicode (optional)
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JQuery selector to use to apply the CSS key/value.
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"""
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selector = kwargs.get('selector', '')
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# Signature 1: set_css(css_dict, [selector=''])
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if len(args) == 1:
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if isinstance(args[0], dict):
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for (key, value) in args[0].items():
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self.set_css(key, value, selector=selector)
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else:
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raise Exception('css_dict must be a dict.')
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# Signature 2: set_css(key, value, [selector=''])
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elif len(args) == 2 or len(args) == 3:
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# Selector can be a positional arg if it's the 3rd value
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if len(args) == 3:
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selector = args[2]
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if selector not in self._css:
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self._css[selector] = {}
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# Only update the property if it has changed.
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key = args[0]
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value = args[1]
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if not (key in self._css[selector] and value in self._css[selector][key]):
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self._css[selector][key] = value
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self.send_state('_css') # Send new state to client.
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else:
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raise Exception('set_css only accepts 1-3 arguments')
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def add_class(self, class_name, selector=""):
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"""Add class[es] to a DOM element
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Parameters
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----------
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class_name: unicode
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Class name(s) to add to the DOM element(s). Multiple class names
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must be space separated.
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selector: unicode (optional)
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JQuery selector to select the DOM element(s) that the class(es) will
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be added to.
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"""
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self.send({"msg_type": "add_class",
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"class_list": class_name,
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"selector": selector})
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def remove_class(self, class_name, selector=""):
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"""Remove class[es] from a DOM element
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Parameters
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----------
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class_name: unicode
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Class name(s) to remove from the DOM element(s). Multiple class
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names must be space separated.
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selector: unicode (optional)
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JQuery selector to select the DOM element(s) that the class(es) will
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be removed from.
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"""
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self.send({"msg_type": "remove_class",
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"class_list": class_name,
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"selector": selector})
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