Source code for panel.io.ipywidget

import logging

from functools import partial

import ipykernel
import param

from bokeh.document.events import MessageSentEvent
from bokeh.document.json import Literal, MessageSent, TypedDict
from bokeh.util.serialization import make_id
from ipykernel.comm import Comm, CommManager
from ipywidgets import Widget
from ipywidgets._version import __protocol_version__
from ipywidgets_bokeh.kernel import (
    BokehKernel, SessionWebsocket, WebsocketStream,
)
from ipywidgets_bokeh.widget import IPyWidget
from tornado.ioloop import IOLoop

from ..util import classproperty
from .state import set_curdoc, state


def _get_kernel(cls=None, doc=None):
    doc = doc or state.curdoc
    if doc is None:
        return _ORIG_KERNEL
    elif doc in state._ipykernels:
        return state._ipykernels[doc]
    state._ipykernels[doc] = kernel = PanelKernel(document=doc, key=str(id(doc)).encode('utf-8'))
    return kernel

def _get_ipywidgets():
    # Support ipywidgets >=8.0 and <8.0
    try:
        from ipywidgets.widgets.widget import _instances as widgets
    except Exception:
        widgets = Widget.widgets
    return widgets

def _on_widget_constructed(widget, doc=None):
    doc = doc or state.curdoc
    if not doc or getattr(widget, '_document', None) not in (doc, None):
        return
    widget._document = doc
    kernel = _get_kernel(doc=doc)
    if widget.comm and isinstance(widget.comm.kernel, PanelKernel):
        return
    args = dict(
        target_name='jupyter.widget', data={}, buffers=[],
        metadata={'version': __protocol_version__}
    )
    if widget._model_id is not None:
        args['comm_id'] = widget._model_id
    widget.comm = Comm(**args)
    kernel.register_widget(widget)

# Patch kernel and widget objects
_ORIG_KERNEL = ipykernel.kernelbase.Kernel._instance
if isinstance(ipykernel.kernelbase.Kernel._instance, BokehKernel):
    ipykernel.kernelbase.Kernel._instance = classproperty(_get_kernel)
Widget.on_widget_constructed(_on_widget_constructed)

# Patch font-awesome CSS onto ipywidgets_bokeh IPyWidget
IPyWidget.__css__ = [
    "https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.5.0/css/font-awesome.css"
]

[docs]class MessageSentBuffers(TypedDict): kind: Literal["MessageSent"] msg_type: str
[docs]class MessageSentEventPatched(MessageSentEvent): """ Patches MessageSentEvent with fix that ensures MessageSent event does not define msg_data (which is an assumption in BokehJS Document.apply_json_patch.) """
[docs] def generate(self, references, buffers): if not isinstance(self.msg_data, bytes): msg = MessageSent( kind=self.kind, msg_type=self.msg_type, msg_data=self.msg_data ) else: msg = MessageSentBuffers( kind=self.kind, msg_type=self.msg_type ) assert buffers is not None buffer_id = make_id() buf = (dict(id=buffer_id), self.msg_data) buffers.append(buf) return msg
[docs]class PanelSessionWebsocket(SessionWebsocket): def __init__(self, *args, **kwargs): super().__init__(*args, **kwargs) self._document = kwargs.pop('document', None) self._queue = [] self._document.on_message("ipywidgets_bokeh", self.receive)
[docs] def send(self, stream, msg_type, content=None, parent=None, ident=None, buffers=None, track=False, header=None, metadata=None): msg = self.msg(msg_type, content=content, parent=parent, header=header, metadata=metadata) msg['channel'] = stream.channel packed = self.pack(msg) if buffers is not None and len(buffers) != 0: buffers = [packed] + buffers nbufs = len(buffers) start = 4*(1 + nbufs) offsets = [start] for buffer in buffers[:-1]: start += memoryview(buffer).nbytes offsets.append(start) u32 = lambda n: n.to_bytes(4, "big") items = [u32(nbufs)] + [ u32(offset) for offset in offsets ] + buffers data = b"".join(items) else: data = packed.decode("utf-8") event = MessageSentEventPatched(self._document, "ipywidgets_bokeh", data) self._queue.append(event) self._document.add_next_tick_callback(self._dispatch)
def _dispatch(self): try: for event in self._queue: self._document.callbacks.trigger_on_change(event) except Exception as e: param.main.warning(f'ipywidgets event dispatch failed with: {e}') finally: self._queue = []
[docs]class PanelKernel(BokehKernel): def __init__(self, key=None, document=None): super().__init__() self.session = PanelSessionWebsocket(document=document, parent=self, key=key) self.stream = self.iopub_socket = WebsocketStream(self.session) self.io_loop = IOLoop.current() self.iopub_socket.channel = 'iopub' self.session.stream = self.iopub_socket self.comm_manager = CommManager(parent=self, kernel=self) self.shell = None self.log = logging.getLogger('fake') comm_msg_types = ['comm_open', 'comm_msg', 'comm_close'] for msg_type in comm_msg_types: handler = getattr(self.comm_manager, msg_type) self.shell_handlers[msg_type] = self._wrap_handler(handler) def register_widget(self, widget): comm = widget.comm comm.kernel = self comm.open() self.comm_manager.register_comm(comm) def _wrap_handler(self, handler): doc = self.session._document def wrapper(*args, **kwargs): with set_curdoc(doc): state.execute(partial(handler, *args, **kwargs), schedule=True) return wrapper