Source code for enable.trait_defs.kiva_font_trait
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#
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# license included in LICENSE.txt and may be redistributed only under
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""" Trait definition for a wxPython-based Kiva font.
"""
from pyface.font import Font as PyfaceFont
from traits.api import DefaultValue, TraitError, TraitType, NoDefaultSpecified
import kiva.constants as kc
from kiva.fonttools.font import Font, FontParseError, simple_parser
#: Expected attributes on the Font class.
font_attrs = [
'face_name', 'size', 'family', 'weight', 'style', 'underline', 'encoding',
]
#: Mapping from Pyface Font generic family names to corresponding constants.
pyface_family_to_kiva_family = {
'default': kc.DEFAULT,
'fantasy': kc.DECORATIVE,
'decorative': kc.DECORATIVE,
'serif': kc.ROMAN,
'roman': kc.ROMAN,
'cursive': kc.SCRIPT,
'script': kc.SCRIPT,
'sans-serif': kc.SWISS,
'swiss': kc.SWISS,
'monospace': kc.MODERN,
'modern': kc.MODERN,
'typewriter': kc.TELETYPE,
'teletype': kc.TELETYPE,
}
[docs]def pyface_font_to_font(font):
"""Convert a Pyface font to an equivalent Kiva Font.
This ignores stretch and some options like small caps and strikethrough
as the Kiva font object can't represent these at the moment.
Parameters
----------
font : Pyface Font instance
The font to convert.
Returns
-------
font : Kiva Font instance
The resulting Kiva Font object.
"""
face_name = font.family[0]
for face in font.family:
if face in pyface_family_to_kiva_family:
family = pyface_family_to_kiva_family[face]
break
else:
family = kc.DEFAULT
size = int(font.size)
weight = font.weight_
style = kc.NORMAL if font.style == 'normal' else kc.ITALIC
underline = 'underline' in font.decorations
return Font(face_name, size, family, weight, style, underline)
[docs]class KivaFont(TraitType):
""" A Trait which casts strings to a Kiva Font value.
"""
#: The default value should be a tuple (factory, args, kwargs)
default_value_type = DefaultValue.callable_and_args
#: The parser to use when converting text to keyword args. This should
#: accept a string and return a dictionary of Font class trait values (ie.
#: "family", "size", "weight", etc.). If it can't parse the string, it
#: should raise FontParseError.
parser = None
def __init__(self, default_value=None, *, parser=simple_parser, **metadata): # noqa: E501
self.parser = parser
default_value = self._get_default_value(default_value)
super().__init__(default_value, **metadata)
[docs] def validate(self, object, name, value):
if isinstance(value, Font):
return value
if isinstance(value, PyfaceFont):
return pyface_font_to_font(value)
if isinstance(value, str):
try:
return Font(**self.parser(value))
except FontParseError:
self.error(object, name, value)
self.error(object, name, value)
[docs] def get_editor(self, trait):
from enable.trait_defs.ui.kiva_font_editor import KivaFontEditor
return KivaFontEditor()
[docs] def clone(self, default_value=NoDefaultSpecified, **metadata):
# Need to override clone due to Traits issue #1629
new = super().clone(NoDefaultSpecified, **metadata)
if default_value is not NoDefaultSpecified:
new.default_value = self._get_default_value(default_value)
new.default_value_type = DefaultValue.callable_and_args
return new
def _get_default_value(self, default_value):
"""Construct a default value suitable for callable_and_args."""
if default_value is not None:
try:
font = self.validate(None, None, default_value)
except TraitError:
raise ValueError(
f"expected {self.info()}, but got {default_value!r}"
)
klass = font.__class__
kwargs = {attr: getattr(font, attr) for attr in font_attrs}
else:
klass = Font
kwargs = {}
return (klass, (), kwargs)
