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# (C) British Crown Copyright 2018 - 2019, Met Office
#
# This file is part of cartopy.
#
# cartopy is free software: you can redistribute it and/or modify it under
# the terms of the GNU Lesser General Public License as published by the
# Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# cartopy is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public License
# along with cartopy. If not, see <https://www.gnu.org/licenses/>.
from __future__ import (absolute_import, division, print_function)
"""
Handles matplotlib styling in a single consistent place.
"""
import warnings
import six
# Define the matplotlib style aliases that cartopy can expand.
# Note: This should not contain the plural aliases
# (e.g. linewidths -> linewidth).
# This is an intended duplication of
# https://github.com/matplotlib/matplotlib/blob/\
# 2d2dab511d22b6cc9c812cfbcca6df3f9bf3094a/lib/matplotlib/patches.py#L20-L26
# Duplication intended to simplify readability, given the small number of
# aliases.
_ALIASES = {
'lw': 'linewidth',
'ls': 'linestyle',
'fc': 'facecolor',
'ec': 'edgecolor',
}
def merge(*style_dicts):
"""
Merge together multiple matplotlib style dictionaries in a predictable way
The approach taken is:
For each style:
* Expand aliases, such as "lw" -> "linewidth", but always prefer
the full form if over-specified (i.e. lw AND linewidth
are both set)
* "color" overwrites "facecolor" and "edgecolor" (as per
matplotlib), UNLESS facecolor == "never", which will be expanded
at finalization to 'none'
>>> style = merge({"lw": 1, "edgecolor": "black", "facecolor": "never"},
... {"linewidth": 2, "color": "gray"})
>>> sorted(style.items())
[('edgecolor', 'gray'), ('facecolor', 'never'), ('linewidth', 2)]
"""
style = {}
facecolor = None
for orig_style in style_dicts:
this_style = orig_style.copy()
for alias_from, alias_to in _ALIASES.items():
alias = this_style.pop(alias_from, None)
if alias_from in orig_style:
# n.b. alias_from doesn't trump alias_to
# (e.g. 'lw' doesn't trump 'linewidth').
this_style.setdefault(alias_to, alias)
color = this_style.pop('color', None)
if 'color' in orig_style:
this_style['edgecolor'] = color
this_style['facecolor'] = color
if isinstance(facecolor, six.string_types) and facecolor == 'never':
requested_color = this_style.pop('facecolor', None)
setting_color = not (
isinstance(requested_color, six.string_types) and
requested_color.lower() == 'none')
if (('fc' in orig_style or 'facecolor' in orig_style) and
setting_color):
warnings.warn('facecolor will have no effect as it has been '
'defined as "never".')
else:
facecolor = this_style.get('facecolor', facecolor)
# Push the remainder of the style into the merged style.
style.update(this_style)
return style
def finalize(style):
"""
Update the given matplotlib style according to cartopy's style rules.
Rules:
1. A facecolor of 'never' is replaced with 'none'.
"""
# Expand 'never' to 'none' if we have it.
facecolor = style.get('facecolor', None)
if facecolor == 'never':
style['facecolor'] = 'none'
return style
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