Source code for bokeh.themes.theme

''' Provide a ``Theme`` class for specify overrides for default values
for Bokeh :class:`~bokeh.model.Model` properties.

from __future__ import absolute_import, print_function

import yaml

from ..core.has_props import HasProps

# whenever we cache that there's nothing themed for a class, we
# use this same dict instance, so we don't have a zillion empty
# dicts in our caches.
_empty_dict = dict()

# Note: in DirectoryHandler and in general we assume this is an
# immutable object, because we share it among sessions and we
# don't monitor it for changes. If you make this mutable by adding
# any kind of setter, you could have to refactor some other code.
[docs]class Theme(object): ''' Args: filename (str, optional) : path to a YAML theme file json (str, optional) : a JSON dictionary specifying theme values Raises: ValueError If neither ``filename`` or ``json`` is supplied. ''' def __init__(self, filename=None, json=None): if (filename is not None) and (json is not None): raise ValueError("Theme should be constructed from a file or from json not both") if filename is not None: f = open(filename) try: json = yaml.load(f) # empty docs result in None rather than {}, fix it. if json is None: json = {} finally: f.close() if json is None: raise ValueError("Theme requires json or a filename to construct") self._json = json if 'attrs' not in self._json: self._json['attrs'] = {} if not isinstance(self._json['attrs'], dict): raise ValueError("theme problem: attrs field should be a dictionary of class names, not %r" % (self._json['attrs'])) for key, value in self._json['attrs'].items(): if not isinstance(value, dict): raise ValueError("theme problem: attrs.%s should be a dictionary of properties, not %r" % (key, value)) self._line_defaults = self._json.get('line_defaults', _empty_dict) self._fill_defaults = self._json.get('fill_defaults', _empty_dict) self._text_defaults = self._json.get('text_defaults', _empty_dict) # mapping from class name to the full set of properties # (including those merged in from base classes) for that # class. self._by_class_cache = {} def _add_glyph_defaults(self, cls, props): from ..models.glyphs import Glyph if issubclass(cls, Glyph): if hasattr(cls, "line_alpha"): props.update(self._line_defaults) if hasattr(cls, "fill_alpha"): props.update(self._fill_defaults) if hasattr(cls, "text_alpha"): props.update(self._text_defaults) def _for_class(self, cls): if cls.__name__ not in self._by_class_cache: attrs = self._json['attrs'] combined = {} # we go in reverse order so that subclass props override base class for base in cls.__mro__[-2::-1]: if not issubclass(base, HasProps): continue self._add_glyph_defaults(base, combined) combined.update(attrs.get(base.__name__, _empty_dict)) if len(combined) == 0: combined = _empty_dict self._by_class_cache[cls.__name__] = combined return self._by_class_cache[cls.__name__]
[docs] def apply_to_model(self, model): ''' Apply this theme to a model. .. warning:: Typically, don't call this method directly. Instead, set the theme on the :class:`~bokeh.document.Document` the model is a part of. ''' model.apply_theme(self._for_class(model.__class__)) # a little paranoia because it would be Bad(tm) to mess # this up... would be nicer if python had a way to freeze # the dict. if len(_empty_dict) > 0: raise RuntimeError("Somebody put stuff in _empty_dict")