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