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512 lines
18 KiB
Python
512 lines
18 KiB
Python
"""
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Defines classes for path effects. The path effects are supported in `.Text`,
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`.Line2D` and `.Patch`.
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.. seealso::
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:ref:`patheffects_guide`
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"""
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from matplotlib.backend_bases import RendererBase
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from matplotlib import colors as mcolors
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from matplotlib import patches as mpatches
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from matplotlib import transforms as mtransforms
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from matplotlib.path import Path
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import numpy as np
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class AbstractPathEffect:
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"""
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A base class for path effects.
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Subclasses should override the ``draw_path`` method to add effect
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functionality.
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"""
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def __init__(self, offset=(0., 0.)):
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"""
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Parameters
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----------
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offset : (float, float), default: (0, 0)
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The (x, y) offset to apply to the path, measured in points.
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"""
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self._offset = offset
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def _offset_transform(self, renderer):
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"""Apply the offset to the given transform."""
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return mtransforms.Affine2D().translate(
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*map(renderer.points_to_pixels, self._offset))
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def _update_gc(self, gc, new_gc_dict):
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"""
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Update the given GraphicsContext with the given dict of properties.
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The keys in the dictionary are used to identify the appropriate
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``set_`` method on the *gc*.
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"""
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new_gc_dict = new_gc_dict.copy()
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dashes = new_gc_dict.pop("dashes", None)
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if dashes:
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gc.set_dashes(**dashes)
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for k, v in new_gc_dict.items():
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set_method = getattr(gc, 'set_' + k, None)
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if not callable(set_method):
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raise AttributeError(f'Unknown property {k}')
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set_method(v)
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return gc
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def draw_path(self, renderer, gc, tpath, affine, rgbFace=None):
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"""
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Derived should override this method. The arguments are the same
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as :meth:`matplotlib.backend_bases.RendererBase.draw_path`
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except the first argument is a renderer.
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"""
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# Get the real renderer, not a PathEffectRenderer.
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if isinstance(renderer, PathEffectRenderer):
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renderer = renderer._renderer
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return renderer.draw_path(gc, tpath, affine, rgbFace)
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class PathEffectRenderer(RendererBase):
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"""
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Implements a Renderer which contains another renderer.
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This proxy then intercepts draw calls, calling the appropriate
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:class:`AbstractPathEffect` draw method.
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.. note::
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Not all methods have been overridden on this RendererBase subclass.
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It may be necessary to add further methods to extend the PathEffects
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capabilities further.
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"""
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def __init__(self, path_effects, renderer):
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"""
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Parameters
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----------
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path_effects : iterable of :class:`AbstractPathEffect`
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The path effects which this renderer represents.
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renderer : `~matplotlib.backend_bases.RendererBase` subclass
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"""
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self._path_effects = path_effects
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self._renderer = renderer
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def copy_with_path_effect(self, path_effects):
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return self.__class__(path_effects, self._renderer)
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def __getattribute__(self, name):
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if name in ['flipy', 'get_canvas_width_height', 'new_gc',
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'points_to_pixels', '_text2path', 'height', 'width']:
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return getattr(self._renderer, name)
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else:
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return object.__getattribute__(self, name)
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def draw_path(self, gc, tpath, affine, rgbFace=None):
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for path_effect in self._path_effects:
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path_effect.draw_path(self._renderer, gc, tpath, affine,
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rgbFace)
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def draw_markers(
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self, gc, marker_path, marker_trans, path, *args, **kwargs):
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# We do a little shimmy so that all markers are drawn for each path
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# effect in turn. Essentially, we induce recursion (depth 1) which is
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# terminated once we have just a single path effect to work with.
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if len(self._path_effects) == 1:
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# Call the base path effect function - this uses the unoptimised
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# approach of calling "draw_path" multiple times.
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return super().draw_markers(gc, marker_path, marker_trans, path,
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*args, **kwargs)
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for path_effect in self._path_effects:
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renderer = self.copy_with_path_effect([path_effect])
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# Recursively call this method, only next time we will only have
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# one path effect.
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renderer.draw_markers(gc, marker_path, marker_trans, path,
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*args, **kwargs)
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def draw_path_collection(self, gc, master_transform, paths, *args,
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**kwargs):
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# We do a little shimmy so that all paths are drawn for each path
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# effect in turn. Essentially, we induce recursion (depth 1) which is
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# terminated once we have just a single path effect to work with.
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if len(self._path_effects) == 1:
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# Call the base path effect function - this uses the unoptimised
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# approach of calling "draw_path" multiple times.
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return super().draw_path_collection(gc, master_transform, paths,
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*args, **kwargs)
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for path_effect in self._path_effects:
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renderer = self.copy_with_path_effect([path_effect])
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# Recursively call this method, only next time we will only have
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# one path effect.
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renderer.draw_path_collection(gc, master_transform, paths,
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*args, **kwargs)
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def open_group(self, s, gid=None):
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return self._renderer.open_group(s, gid)
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def close_group(self, s):
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return self._renderer.close_group(s)
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class Normal(AbstractPathEffect):
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"""
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The "identity" PathEffect.
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The Normal PathEffect's sole purpose is to draw the original artist with
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no special path effect.
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"""
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def _subclass_with_normal(effect_class):
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"""
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Create a PathEffect class combining *effect_class* and a normal draw.
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"""
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class withEffect(effect_class):
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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super().draw_path(renderer, gc, tpath, affine, rgbFace)
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renderer.draw_path(gc, tpath, affine, rgbFace)
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withEffect.__name__ = f"with{effect_class.__name__}"
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withEffect.__qualname__ = f"with{effect_class.__name__}"
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withEffect.__doc__ = f"""
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A shortcut PathEffect for applying `.{effect_class.__name__}` and then
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drawing the original Artist.
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With this class you can use ::
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artist.set_path_effects([patheffects.with{effect_class.__name__}()])
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as a shortcut for ::
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artist.set_path_effects([patheffects.{effect_class.__name__}(),
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patheffects.Normal()])
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"""
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# Docstring inheritance doesn't work for locally-defined subclasses.
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withEffect.draw_path.__doc__ = effect_class.draw_path.__doc__
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return withEffect
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class Stroke(AbstractPathEffect):
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"""A line based PathEffect which re-draws a stroke."""
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def __init__(self, offset=(0, 0), **kwargs):
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"""
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The path will be stroked with its gc updated with the given
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keyword arguments, i.e., the keyword arguments should be valid
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gc parameter values.
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"""
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super().__init__(offset)
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self._gc = kwargs
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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"""Draw the path with updated gc."""
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gc0 = renderer.new_gc() # Don't modify gc, but a copy!
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gc0.copy_properties(gc)
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gc0 = self._update_gc(gc0, self._gc)
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renderer.draw_path(
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gc0, tpath, affine + self._offset_transform(renderer), rgbFace)
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gc0.restore()
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withStroke = _subclass_with_normal(effect_class=Stroke)
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class SimplePatchShadow(AbstractPathEffect):
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"""A simple shadow via a filled patch."""
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def __init__(self, offset=(2, -2),
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shadow_rgbFace=None, alpha=None,
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rho=0.3, **kwargs):
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"""
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Parameters
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----------
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offset : (float, float), default: (2, -2)
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The (x, y) offset of the shadow in points.
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shadow_rgbFace : :mpltype:`color`
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The shadow color.
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alpha : float, default: 0.3
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The alpha transparency of the created shadow patch.
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rho : float, default: 0.3
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A scale factor to apply to the rgbFace color if *shadow_rgbFace*
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is not specified.
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**kwargs
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Extra keywords are stored and passed through to
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:meth:`AbstractPathEffect._update_gc`.
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"""
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super().__init__(offset)
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if shadow_rgbFace is None:
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self._shadow_rgbFace = shadow_rgbFace
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else:
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self._shadow_rgbFace = mcolors.to_rgba(shadow_rgbFace)
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if alpha is None:
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alpha = 0.3
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self._alpha = alpha
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self._rho = rho
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#: The dictionary of keywords to update the graphics collection with.
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self._gc = kwargs
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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"""
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Overrides the standard draw_path to add the shadow offset and
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necessary color changes for the shadow.
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"""
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gc0 = renderer.new_gc() # Don't modify gc, but a copy!
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gc0.copy_properties(gc)
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if self._shadow_rgbFace is None:
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r, g, b = (rgbFace or (1., 1., 1.))[:3]
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# Scale the colors by a factor to improve the shadow effect.
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shadow_rgbFace = (r * self._rho, g * self._rho, b * self._rho)
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else:
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shadow_rgbFace = self._shadow_rgbFace
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gc0.set_foreground("none")
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gc0.set_alpha(self._alpha)
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gc0.set_linewidth(0)
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gc0 = self._update_gc(gc0, self._gc)
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renderer.draw_path(
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gc0, tpath, affine + self._offset_transform(renderer),
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shadow_rgbFace)
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gc0.restore()
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withSimplePatchShadow = _subclass_with_normal(effect_class=SimplePatchShadow)
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class SimpleLineShadow(AbstractPathEffect):
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"""A simple shadow via a line."""
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def __init__(self, offset=(2, -2),
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shadow_color='k', alpha=0.3, rho=0.3, **kwargs):
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"""
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Parameters
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----------
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offset : (float, float), default: (2, -2)
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The (x, y) offset to apply to the path, in points.
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shadow_color : :mpltype:`color`, default: 'black'
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The shadow color.
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A value of ``None`` takes the original artist's color
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with a scale factor of *rho*.
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alpha : float, default: 0.3
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The alpha transparency of the created shadow patch.
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rho : float, default: 0.3
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A scale factor to apply to the rgbFace color if *shadow_color*
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is ``None``.
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**kwargs
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Extra keywords are stored and passed through to
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:meth:`AbstractPathEffect._update_gc`.
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"""
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super().__init__(offset)
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if shadow_color is None:
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self._shadow_color = shadow_color
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else:
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self._shadow_color = mcolors.to_rgba(shadow_color)
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self._alpha = alpha
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self._rho = rho
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#: The dictionary of keywords to update the graphics collection with.
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self._gc = kwargs
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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"""
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Overrides the standard draw_path to add the shadow offset and
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necessary color changes for the shadow.
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"""
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gc0 = renderer.new_gc() # Don't modify gc, but a copy!
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gc0.copy_properties(gc)
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if self._shadow_color is None:
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r, g, b = (gc0.get_foreground() or (1., 1., 1.))[:3]
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# Scale the colors by a factor to improve the shadow effect.
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shadow_rgbFace = (r * self._rho, g * self._rho, b * self._rho)
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else:
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shadow_rgbFace = self._shadow_color
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gc0.set_foreground(shadow_rgbFace)
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gc0.set_alpha(self._alpha)
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gc0 = self._update_gc(gc0, self._gc)
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renderer.draw_path(
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gc0, tpath, affine + self._offset_transform(renderer))
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gc0.restore()
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class PathPatchEffect(AbstractPathEffect):
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"""
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Draws a `.PathPatch` instance whose Path comes from the original
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PathEffect artist.
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"""
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def __init__(self, offset=(0, 0), **kwargs):
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"""
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Parameters
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----------
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offset : (float, float), default: (0, 0)
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The (x, y) offset to apply to the path, in points.
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**kwargs
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All keyword arguments are passed through to the
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:class:`~matplotlib.patches.PathPatch` constructor. The
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properties which cannot be overridden are "path", "clip_box"
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"transform" and "clip_path".
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"""
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super().__init__(offset=offset)
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self.patch = mpatches.PathPatch([], **kwargs)
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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self.patch._path = tpath
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self.patch.set_transform(affine + self._offset_transform(renderer))
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self.patch.set_clip_box(gc.get_clip_rectangle())
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clip_path = gc.get_clip_path()
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if clip_path and self.patch.get_clip_path() is None:
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self.patch.set_clip_path(*clip_path)
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self.patch.draw(renderer)
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class TickedStroke(AbstractPathEffect):
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"""
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A line-based PathEffect which draws a path with a ticked style.
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This line style is frequently used to represent constraints in
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optimization. The ticks may be used to indicate that one side
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of the line is invalid or to represent a closed boundary of a
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domain (i.e. a wall or the edge of a pipe).
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The spacing, length, and angle of ticks can be controlled.
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This line style is sometimes referred to as a hatched line.
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See also the :doc:`/gallery/misc/tickedstroke_demo` example.
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"""
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def __init__(self, offset=(0, 0),
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spacing=10.0, angle=45.0, length=np.sqrt(2),
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**kwargs):
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"""
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Parameters
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----------
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offset : (float, float), default: (0, 0)
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The (x, y) offset to apply to the path, in points.
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spacing : float, default: 10.0
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The spacing between ticks in points.
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angle : float, default: 45.0
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The angle between the path and the tick in degrees. The angle
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is measured as if you were an ant walking along the curve, with
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zero degrees pointing directly ahead, 90 to your left, -90
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to your right, and 180 behind you. To change side of the ticks,
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change sign of the angle.
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length : float, default: 1.414
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The length of the tick relative to spacing.
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Recommended length = 1.414 (sqrt(2)) when angle=45, length=1.0
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when angle=90 and length=2.0 when angle=60.
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**kwargs
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Extra keywords are stored and passed through to
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:meth:`AbstractPathEffect._update_gc`.
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Examples
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--------
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See :doc:`/gallery/misc/tickedstroke_demo`.
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"""
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super().__init__(offset)
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self._spacing = spacing
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self._angle = angle
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self._length = length
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self._gc = kwargs
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def draw_path(self, renderer, gc, tpath, affine, rgbFace):
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"""Draw the path with updated gc."""
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# Do not modify the input! Use copy instead.
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gc0 = renderer.new_gc()
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gc0.copy_properties(gc)
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gc0 = self._update_gc(gc0, self._gc)
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trans = affine + self._offset_transform(renderer)
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theta = -np.radians(self._angle)
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trans_matrix = np.array([[np.cos(theta), -np.sin(theta)],
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[np.sin(theta), np.cos(theta)]])
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# Convert spacing parameter to pixels.
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spacing_px = renderer.points_to_pixels(self._spacing)
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# Transform before evaluation because to_polygons works at resolution
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# of one -- assuming it is working in pixel space.
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transpath = affine.transform_path(tpath)
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# Evaluate path to straight line segments that can be used to
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# construct line ticks.
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polys = transpath.to_polygons(closed_only=False)
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for p in polys:
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x = p[:, 0]
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y = p[:, 1]
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# Can not interpolate points or draw line if only one point in
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# polyline.
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if x.size < 2:
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continue
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# Find distance between points on the line
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ds = np.hypot(x[1:] - x[:-1], y[1:] - y[:-1])
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# Build parametric coordinate along curve
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s = np.concatenate(([0.0], np.cumsum(ds)))
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s_total = s[-1]
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num = int(np.ceil(s_total / spacing_px)) - 1
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# Pick parameter values for ticks.
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s_tick = np.linspace(spacing_px/2, s_total - spacing_px/2, num)
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# Find points along the parameterized curve
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x_tick = np.interp(s_tick, s, x)
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y_tick = np.interp(s_tick, s, y)
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# Find unit vectors in local direction of curve
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delta_s = self._spacing * .001
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u = (np.interp(s_tick + delta_s, s, x) - x_tick) / delta_s
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v = (np.interp(s_tick + delta_s, s, y) - y_tick) / delta_s
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# Normalize slope into unit slope vector.
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n = np.hypot(u, v)
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mask = n == 0
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n[mask] = 1.0
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uv = np.array([u / n, v / n]).T
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uv[mask] = np.array([0, 0]).T
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# Rotate and scale unit vector into tick vector
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dxy = np.dot(uv, trans_matrix) * self._length * spacing_px
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# Build tick endpoints
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x_end = x_tick + dxy[:, 0]
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y_end = y_tick + dxy[:, 1]
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# Interleave ticks to form Path vertices
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xyt = np.empty((2 * num, 2), dtype=x_tick.dtype)
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xyt[0::2, 0] = x_tick
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xyt[1::2, 0] = x_end
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xyt[0::2, 1] = y_tick
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xyt[1::2, 1] = y_end
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# Build up vector of Path codes
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codes = np.tile([Path.MOVETO, Path.LINETO], num)
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# Construct and draw resulting path
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h = Path(xyt, codes)
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# Transform back to data space during render
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renderer.draw_path(gc0, h, affine.inverted() + trans, rgbFace)
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gc0.restore()
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withTickedStroke = _subclass_with_normal(effect_class=TickedStroke)
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