"""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 Widget(LoggingConfigurable): # Shared declarations _keys = [] # Public declarations 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.""") parent = Instance('IPython.html.widgets.widget.Widget') visible = Bool(True, help="Whether or not the widget is visible.") def _parent_changed(self, name, old, new): if self._displayed: raise Exception('Parent cannot be set because widget has been displayed.') elif new == self: raise Exception('Parent cannot be set to self.') else: # Parent/child association if new is not None and not self in new._children: new._children.append(self) if old is not None and self in old._children: old._children.remove(self) # Private/protected declarations _property_lock = (None, None) # Last updated (key, value) from the front-end. Prevents echo. _css = Dict() # Internal CSS property dict _displayed = False _comm = None def __init__(self, **kwargs): """Public constructor Parameters ---------- parent : Widget instance (optional) Widget that this widget instance is child of. When the widget is displayed in the frontend, it's corresponding view will be made child of the parent's view if the parent's view exists already. If the parent's view is displayed, it will automatically display this widget's default view as it's child. The default view can be set via the default_view_name property. """ self._children = [] self._display_callbacks = [] self._msg_callbacks = [] super(Widget, self).__init__(**kwargs) # Register after init to allow default values to be specified self.on_trait_change(self._handle_property_changed, self.keys) 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.""" try: self._comm.close() del self._comm except: pass # Comm doesn't exist and/or is already closed. # Properties def _get_keys(self): keys = ['visible', '_css'] keys.extend(self._keys) return keys keys = property(_get_keys) # 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 proeprty 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 \ and self._comm is not None: # TODO: Validate properties. # Send new state to frontend self.send_state(key=name) def _handle_close(self): """Called when the comm is closed by the frontend.""" self._comm = None def _handle_displayed(self, view_name, parent=None): """Called when a view has been displayed for this widget instance Parameters ---------- view_name: unicode Name of the view that was displayed. parent: Widget instance [optional] Widget that this widget should be displayed as a child of.""" 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, view_name) elif nargs == 3: handler(self, view_name, parent) else: raise TypeError('Widget display callback must ' \ 'accept 0-2 arguments, not %d.' % nargs) # 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. """ if self._comm is not None: state = {} # If a key is provided, just send the state of that key. keys = [] if key is None: keys.extend(self.keys) else: keys.append(key) for key in self.keys: try: state[key] = getattr(self, key) except Exception as e: pass # Eat errors, nom nom nom self._comm.send({"method": "update", "state": state}) 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. """ if self._comm is not None: self._comm.send({"method": "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. """ if self._comm is not None: self._comm.send({"method": "remove_class", "class_list": class_name, "selector": selector}) 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. """ if self._comm is not None: self._comm.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, view_name, parent) 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, view_name=None): """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.""" if not view_name: view_name = self.default_view_name # 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._handle_close) # Make sure model is syncronized self.send_state() # Show view. if self.parent is None or self.parent._comm is None: self._comm.send({"method": "display", "view_name": view_name}) self._handle_displayed(view_name) else: self._comm.send({"method": "display", "view_name": view_name, "parent": self.parent._comm.comm_id}) self._handle_displayed(view_name, self.parent) self._displayed = True # Now display children if any. for child in self._children: if child != self: child._repr_widget_() return None