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"""Base Widget class. Allows user to create widgets in the back-end that render
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in the IPython notebook front-end.
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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 contextlib import contextmanager
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import collections
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from IPython.core.getipython import get_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.importstring import import_item
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from IPython.utils.traitlets import Unicode, Dict, Instance, Bool, List, \
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CaselessStrEnum, Tuple, CUnicode, Int, Set
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from IPython.utils.py3compat import string_types
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from .trait_types import Color
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def _widget_to_json(x):
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if isinstance(x, dict):
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return {k: _widget_to_json(v) for k, v in x.items()}
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elif isinstance(x, (list, tuple)):
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return [_widget_to_json(v) for v in x]
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elif isinstance(x, Widget):
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return "IPY_MODEL_" + x.model_id
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else:
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return x
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def _json_to_widget(x):
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if isinstance(x, dict):
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return {k: _json_to_widget(v) for k, v in x.items()}
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elif isinstance(x, (list, tuple)):
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return [_json_to_widget(v) for v in x]
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elif isinstance(x, string_types) and x.startswith('IPY_MODEL_') and x[10:] in Widget.widgets:
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return Widget.widgets[x[10:]]
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else:
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return x
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widget_serialization = {
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'from_json': _json_to_widget,
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'to_json': _widget_to_json
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}
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#-----------------------------------------------------------------------------
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# Classes
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#-----------------------------------------------------------------------------
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class CallbackDispatcher(LoggingConfigurable):
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"""A structure for registering and running callbacks"""
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callbacks = List()
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def __call__(self, *args, **kwargs):
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"""Call all of the registered callbacks."""
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value = None
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for callback in self.callbacks:
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try:
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local_value = callback(*args, **kwargs)
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except Exception as e:
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ip = get_ipython()
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if ip is None:
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self.log.warn("Exception in callback %s: %s", callback, e, exc_info=True)
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else:
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ip.showtraceback()
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else:
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value = local_value if local_value is not None else value
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return value
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def register_callback(self, callback, remove=False):
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"""(Un)Register a callback
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Parameters
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----------
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callback: method handle
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Method to be registered or unregistered.
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remove=False: bool
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Whether to unregister the callback."""
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# (Un)Register the callback.
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if remove and callback in self.callbacks:
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self.callbacks.remove(callback)
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elif not remove and callback not in self.callbacks:
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self.callbacks.append(callback)
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def _show_traceback(method):
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"""decorator for showing tracebacks in IPython"""
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def m(self, *args, **kwargs):
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try:
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return(method(self, *args, **kwargs))
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except Exception as e:
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ip = get_ipython()
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if ip is None:
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self.log.warn("Exception in widget method %s: %s", method, e, exc_info=True)
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else:
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ip.showtraceback()
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return m
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def register(key=None):
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"""Returns a decorator registering a widget class in the widget registry.
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If no key is provided, the class name is used as a key. A key is
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provided for each core IPython widget so that the frontend can use
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this key regardless of the language of the kernel"""
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def wrap(widget):
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l = key if key is not None else widget.__module__ + widget.__name__
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Widget.widget_types[l] = widget
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return widget
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return wrap
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class Widget(LoggingConfigurable):
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#-------------------------------------------------------------------------
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# Class attributes
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#-------------------------------------------------------------------------
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_widget_construction_callback = None
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widgets = {}
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widget_types = {}
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@staticmethod
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def on_widget_constructed(callback):
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"""Registers a callback to be called when a widget is constructed.
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The callback must have the following signature:
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callback(widget)"""
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Widget._widget_construction_callback = callback
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@staticmethod
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def _call_widget_constructed(widget):
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"""Static method, called when a widget is constructed."""
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if Widget._widget_construction_callback is not None and callable(Widget._widget_construction_callback):
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Widget._widget_construction_callback(widget)
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@staticmethod
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def handle_comm_opened(comm, msg):
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"""Static method, called when a widget is constructed."""
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widget_class = import_item(msg['content']['data']['widget_class'])
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widget = widget_class(comm=comm)
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#-------------------------------------------------------------------------
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# Traits
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#-------------------------------------------------------------------------
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_model_module = Unicode(None, allow_none=True, help="""A requirejs module name
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in which to find _model_name. If empty, look in the global registry.""")
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_model_name = Unicode('WidgetModel', help="""Name of the backbone model
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registered in the front-end to create and sync this widget with.""")
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_view_module = Unicode(help="""A requirejs module in which to find _view_name.
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If empty, look in the global registry.""", sync=True)
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_view_name = Unicode(None, allow_none=True, help="""Default view registered in the front-end
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to use to represent the widget.""", sync=True)
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comm = Instance('IPython.kernel.comm.Comm', allow_none=True)
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msg_throttle = Int(3, sync=True, help="""Maximum number of msgs the
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front-end can send before receiving an idle msg from the back-end.""")
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version = Int(0, sync=True, help="""Widget's version""")
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keys = List()
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def _keys_default(self):
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return [name for name in self.traits(sync=True)]
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_property_lock = Tuple((None, None))
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_send_state_lock = Int(0)
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_states_to_send = Set()
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_display_callbacks = Instance(CallbackDispatcher, ())
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_msg_callbacks = Instance(CallbackDispatcher, ())
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#-------------------------------------------------------------------------
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# (Con/de)structor
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#-------------------------------------------------------------------------
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def __init__(self, **kwargs):
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"""Public constructor"""
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self._model_id = kwargs.pop('model_id', None)
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super(Widget, self).__init__(**kwargs)
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Widget._call_widget_constructed(self)
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self.open()
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def __del__(self):
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"""Object disposal"""
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self.close()
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#-------------------------------------------------------------------------
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# Properties
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#-------------------------------------------------------------------------
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def open(self):
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"""Open a comm to the frontend if one isn't already open."""
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if self.comm is None:
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args = dict(target_name='ipython.widget',
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data={'model_name': self._model_name,
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'model_module': self._model_module})
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if self._model_id is not None:
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args['comm_id'] = self._model_id
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self.comm = Comm(**args)
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def _comm_changed(self, name, new):
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"""Called when the comm is changed."""
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if new is None:
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return
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self._model_id = self.model_id
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self.comm.on_msg(self._handle_msg)
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Widget.widgets[self.model_id] = self
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# first update
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self.send_state()
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@property
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def model_id(self):
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"""Gets the model id of this widget.
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If a Comm doesn't exist yet, a Comm will be created automagically."""
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return self.comm.comm_id
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#-------------------------------------------------------------------------
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# Methods
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#-------------------------------------------------------------------------
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def close(self):
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"""Close method.
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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 front-end."""
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if self.comm is not None:
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Widget.widgets.pop(self.model_id, None)
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self.comm.close()
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self.comm = None
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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 front-end.
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Parameters
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----------
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key : unicode, or iterable (optional)
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A single property's name or iterable of property names to sync with the front-end.
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"""
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state, buffer_keys, buffers = self.get_state(key=key)
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msg = {"method": "update", "state": state}
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if buffer_keys:
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msg['buffers'] = buffer_keys
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self._send(msg, buffers=buffers)
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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 or iterable (optional)
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A single property's name or iterable of property names to get.
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Returns
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-------
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state : dict of states
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buffer_keys : list of strings
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the values that are stored in buffers
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buffers : list of binary memoryviews
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values to transmit in binary
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metadata : dict
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metadata for each field: {key: metadata}
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"""
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if key is None:
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keys = self.keys
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elif isinstance(key, string_types):
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keys = [key]
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elif isinstance(key, collections.Iterable):
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keys = key
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else:
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raise ValueError("key must be a string, an iterable of keys, or None")
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state = {}
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buffers = []
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buffer_keys = []
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for k in keys:
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f = self.trait_metadata(k, 'to_json', self._trait_to_json)
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value = getattr(self, k)
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serialized = f(value)
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if isinstance(serialized, memoryview):
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buffers.append(serialized)
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buffer_keys.append(k)
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else:
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state[k] = serialized
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return state, buffer_keys, buffers
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def set_state(self, sync_data):
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"""Called when a state is received from the front-end."""
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for name in self.keys:
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if name in sync_data:
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json_value = sync_data[name]
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from_json = self.trait_metadata(name, 'from_json', self._trait_from_json)
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with self._lock_property(name, json_value):
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setattr(self, name, from_json(json_value))
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def send(self, content, buffers=None):
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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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buffers : list of binary buffers
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Binary buffers to send with message
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"""
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self._send({"method": "custom", "content": content}, buffers=buffers)
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def on_msg(self, callback, remove=False):
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"""(Un)Register a custom msg receive callback.
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Parameters
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----------
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callback: callable
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callback will be passed three arguments when a message arrives::
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callback(widget, content, buffers)
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remove: bool
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True if the callback should be unregistered."""
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self._msg_callbacks.register_callback(callback, remove=remove)
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def on_displayed(self, callback, remove=False):
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"""(Un)Register a widget displayed callback.
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Parameters
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----------
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callback: method handler
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Must have a signature of::
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callback(widget, **kwargs)
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kwargs from display are 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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self._display_callbacks.register_callback(callback, remove=remove)
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def add_trait(self, traitname, trait):
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"""Dynamically add a trait attribute to the Widget."""
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super(Widget, self).add_trait(traitname, trait)
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if trait.get_metadata('sync'):
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self.keys.append(traitname)
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self.send_state(traitname)
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#-------------------------------------------------------------------------
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# Support methods
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#-------------------------------------------------------------------------
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@contextmanager
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def _lock_property(self, key, value):
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"""Lock a property-value pair.
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The value should be the JSON state of the property.
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NOTE: This, in addition to the single lock for all state changes, is
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flawed. In the future we may want to look into buffering state changes
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back to the front-end."""
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self._property_lock = (key, value)
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try:
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yield
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finally:
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self._property_lock = (None, None)
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|
|
|
@contextmanager
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|
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def hold_sync(self):
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"""Hold syncing any state until the context manager is released"""
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# We increment a value so that this can be nested. Syncing will happen when
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# all levels have been released.
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self._send_state_lock += 1
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try:
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yield
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finally:
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self._send_state_lock -=1
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|
|
if self._send_state_lock == 0:
|
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self.send_state(self._states_to_send)
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|
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self._states_to_send.clear()
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|
|
|
def _should_send_property(self, key, value):
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|
"""Check the property lock (property_lock)"""
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|
|
to_json = self.trait_metadata(key, 'to_json', self._trait_to_json)
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|
|
if (key == self._property_lock[0]
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|
|
and to_json(value) == self._property_lock[1]):
|
|
|
return False
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|
|
elif self._send_state_lock > 0:
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|
|
self._states_to_send.add(key)
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|
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return False
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|
|
else:
|
|
|
return True
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|
|
|
|
|
# Event handlers
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|
|
@_show_traceback
|
|
|
def _handle_msg(self, msg):
|
|
|
"""Called when a msg is received from the front-end"""
|
|
|
data = msg['content']['data']
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|
|
method = data['method']
|
|
|
|
|
|
# Handle backbone sync methods CREATE, PATCH, and UPDATE all in one.
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|
|
if method == 'backbone':
|
|
|
if 'sync_data' in data:
|
|
|
# get binary buffers too
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|
|
sync_data = data['sync_data']
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|
|
for i,k in enumerate(data.get('buffer_keys', [])):
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|
sync_data[k] = msg['buffers'][i]
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|
|
self.set_state(sync_data) # handles all methods
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|
|
|
|
|
# Handle a state request.
|
|
|
elif method == 'request_state':
|
|
|
self.send_state()
|
|
|
|
|
|
# Handle a custom msg from the front-end.
|
|
|
elif method == 'custom':
|
|
|
if 'content' in data:
|
|
|
self._handle_custom_msg(data['content'], msg['buffers'])
|
|
|
|
|
|
# Catch remainder.
|
|
|
else:
|
|
|
self.log.error('Unknown front-end to back-end widget msg with method "%s"' % method)
|
|
|
|
|
|
def _handle_custom_msg(self, content, buffers):
|
|
|
"""Called when a custom msg is received."""
|
|
|
self._msg_callbacks(self, content, buffers)
|
|
|
|
|
|
def _notify_trait(self, name, old_value, new_value):
|
|
|
"""Called when a property has been changed."""
|
|
|
# Trigger default traitlet callback machinery. This allows any user
|
|
|
# registered validation to be processed prior to allowing the widget
|
|
|
# machinery to handle the state.
|
|
|
LoggingConfigurable._notify_trait(self, name, old_value, new_value)
|
|
|
|
|
|
# Send the state after the user registered callbacks for trait changes
|
|
|
# have all fired (allows for user to validate values).
|
|
|
if self.comm is not None and name in self.keys:
|
|
|
# Make sure this isn't information that the front-end just sent us.
|
|
|
if self._should_send_property(name, new_value):
|
|
|
# Send new state to front-end
|
|
|
self.send_state(key=name)
|
|
|
|
|
|
def _handle_displayed(self, **kwargs):
|
|
|
"""Called when a view has been displayed for this widget instance"""
|
|
|
self._display_callbacks(self, **kwargs)
|
|
|
|
|
|
def _trait_to_json(self, x):
|
|
|
"""Convert a trait value to json."""
|
|
|
return x
|
|
|
|
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def _trait_from_json(self, x):
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"""Convert json values to objects."""
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return x
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def _ipython_display_(self, **kwargs):
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"""Called when `IPython.display.display` is called on the widget."""
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# Show view.
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if self._view_name is not None:
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self._send({"method": "display"})
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self._handle_displayed(**kwargs)
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def _send(self, msg, buffers=None):
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"""Sends a message to the model in the front-end."""
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self.comm.send(data=msg, buffers=buffers)
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class DOMWidget(Widget):
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visible = Bool(True, allow_none=True, help="Whether the widget is visible. False collapses the empty space, while None preserves the empty space.", sync=True)
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_css = Tuple(sync=True, help="CSS property list: (selector, key, value)")
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_dom_classes = Tuple(sync=True, help="DOM classes applied to widget.$el.")
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width = CUnicode(sync=True)
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height = CUnicode(sync=True)
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# A default padding of 2.5 px makes the widgets look nice when displayed inline.
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padding = CUnicode(sync=True)
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margin = CUnicode(sync=True)
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color = Color(None, allow_none=True, sync=True)
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background_color = Color(None, allow_none=True, sync=True)
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border_color = Color(None, allow_none=True, sync=True)
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border_width = CUnicode(sync=True)
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border_radius = CUnicode(sync=True)
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border_style = CaselessStrEnum(values=[ # http://www.w3schools.com/cssref/pr_border-style.asp
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'none',
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'hidden',
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'dotted',
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'dashed',
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'solid',
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'double',
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'groove',
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'ridge',
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'inset',
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'outset',
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'initial',
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'inherit', ''],
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default_value='', sync=True)
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font_style = CaselessStrEnum(values=[ # http://www.w3schools.com/cssref/pr_font_font-style.asp
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'normal',
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'italic',
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'oblique',
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'initial',
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'inherit', ''],
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default_value='', sync=True)
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font_weight = CaselessStrEnum(values=[ # http://www.w3schools.com/cssref/pr_font_weight.asp
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'normal',
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'bold',
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'bolder',
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'lighter',
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'initial',
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'inherit', ''] + list(map(str, range(100,1000,100))),
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default_value='', sync=True)
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font_size = CUnicode(sync=True)
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font_family = Unicode(sync=True)
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def __init__(self, *pargs, **kwargs):
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super(DOMWidget, self).__init__(*pargs, **kwargs)
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def _validate_border(name, old, new):
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if new is not None and new != '':
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if name != 'border_width' and not self.border_width:
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self.border_width = 1
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if name != 'border_style' and self.border_style == '':
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self.border_style = 'solid'
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self.on_trait_change(_validate_border, ['border_width', 'border_style', 'border_color'])
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