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diff --git a/share/extensions/inkex/elements/_filters.py b/share/extensions/inkex/elements/_filters.py
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+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2020 Martin Owens <doctormo@gmail.com>
+#                    Sergei Izmailov <sergei.a.izmailov@gmail.com>
+#                    Thomas Holder <thomas.holder@schrodinger.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 2 of the License, or
+# (at your option) any later version.
+#
+# This program 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 General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program; if not, write to the Free Software
+# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+#
+# pylint: disable=arguments-differ
+"""
+Element interface for patterns, filters, gradients and path effects.
+"""
+from __future__ import annotations
+from typing import List, Tuple, TYPE_CHECKING, Optional
+
+from lxml import etree
+
+from ..transforms import Transform
+from ..utils import parse_percent
+
+from ..styles import Style
+
+from ._utils import addNS
+from ._base import BaseElement
+
+
+if TYPE_CHECKING:
+    from ._svg import SvgDocumentElement
+
+
+class Filter(BaseElement):
+    """A filter (usually in defs)"""
+
+    tag_name = "filter"
+
+    def add_primitive(self, fe_type, **args):
+        """Create a filter primitive with the given arguments"""
+        elem = etree.SubElement(self, addNS(fe_type, "svg"))
+        elem.update(**args)
+        return elem
+
+    class Primitive(BaseElement):
+        """Any filter primitive"""
+
+    class Blend(Primitive):
+        """Blend Filter element"""
+
+        tag_name = "feBlend"
+
+    class ColorMatrix(Primitive):
+        """ColorMatrix Filter element"""
+
+        tag_name = "feColorMatrix"
+
+    class ComponentTransfer(Primitive):
+        """ComponentTransfer Filter element"""
+
+        tag_name = "feComponentTransfer"
+
+    class Composite(Primitive):
+        """Composite Filter element"""
+
+        tag_name = "feComposite"
+
+    class ConvolveMatrix(Primitive):
+        """ConvolveMatrix Filter element"""
+
+        tag_name = "feConvolveMatrix"
+
+    class DiffuseLighting(Primitive):
+        """DiffuseLightning Filter element"""
+
+        tag_name = "feDiffuseLighting"
+
+    class DisplacementMap(Primitive):
+        """Flood Filter element"""
+
+        tag_name = "feDisplacementMap"
+
+    class Flood(Primitive):
+        """DiffuseLightning Filter element"""
+
+        tag_name = "feFlood"
+
+    class GaussianBlur(Primitive):
+        """GaussianBlur Filter element"""
+
+        tag_name = "feGaussianBlur"
+
+    class Image(Primitive):
+        """Image Filter element"""
+
+        tag_name = "feImage"
+
+    class Merge(Primitive):
+        """Merge Filter element"""
+
+        tag_name = "feMerge"
+
+    class Morphology(Primitive):
+        """Morphology Filter element"""
+
+        tag_name = "feMorphology"
+
+    class Offset(Primitive):
+        """Offset Filter element"""
+
+        tag_name = "feOffset"
+
+    class SpecularLighting(Primitive):
+        """SpecularLighting Filter element"""
+
+        tag_name = "feSpecularLighting"
+
+    class Tile(Primitive):
+        """Tile Filter element"""
+
+        tag_name = "feTile"
+
+    class Turbulence(Primitive):
+        """Turbulence Filter element"""
+
+        tag_name = "feTurbulence"
+
+
+class Stop(BaseElement):
+    """Gradient stop
+
+    .. versionadded:: 1.1"""
+
+    tag_name = "stop"
+
+    @property
+    def offset(self) -> float:
+        """The offset of the gradient stop"""
+        return self.get("offset")
+
+    @offset.setter
+    def offset(self, number):
+        self.set("offset", number)
+
+    def interpolate(self, other, fraction):
+        """Interpolate gradient stops"""
+        from ..tween import StopInterpolator
+
+        return StopInterpolator(self, other).interpolate(fraction)
+
+
+class Pattern(BaseElement):
+    """Pattern element which is used in the def to control repeating fills"""
+
+    tag_name = "pattern"
+    WRAPPED_ATTRS = BaseElement.WRAPPED_ATTRS + (("patternTransform", Transform),)
+
+
+class Gradient(BaseElement):
+    """A gradient instruction usually in the defs."""
+
+    WRAPPED_ATTRS = BaseElement.WRAPPED_ATTRS + (("gradientTransform", Transform),)
+    """Additional to the :attr:`~inkex.elements._base.BaseElement.WRAPPED_ATTRS` of 
+    :class:`~inkex.elements._base.BaseElement`, ``gradientTransform`` is wrapped."""
+
+    orientation_attributes = ()  # type: Tuple[str, ...]
+    """
+    .. versionadded:: 1.1
+    """
+
+    @property
+    def stops(self):
+        """Return an ordered list of own or linked stop nodes
+
+        .. versionadded:: 1.1"""
+        gradcolor = (
+            self.href
+            if isinstance(self.href, (LinearGradient, RadialGradient))
+            else self
+        )
+        return sorted(
+            [child for child in gradcolor if isinstance(child, Stop)],
+            key=lambda x: parse_percent(x.offset),
+        )
+
+    @property
+    def stop_offsets(self):
+        # type: () -> List[float]
+        """Return a list of own or linked stop offsets
+
+        .. versionadded:: 1.1"""
+        return [child.offset for child in self.stops]
+
+    @property
+    def stop_styles(self):  # type: () -> List[Style]
+        """Return a list of own or linked offset styles
+
+        .. versionadded:: 1.1"""
+        return [child.style for child in self.stops]
+
+    def remove_orientation(self):
+        """Remove all orientation attributes from this element
+
+        .. versionadded:: 1.1"""
+        for attr in self.orientation_attributes:
+            self.pop(attr)
+
+    def interpolate(
+        self,
+        other: LinearGradient,
+        fraction: float,
+        svg: Optional[SvgDocumentElement] = None,
+    ):
+        """Interpolate with another gradient.
+
+        .. versionadded:: 1.1"""
+        from ..tween import GradientInterpolator
+
+        return GradientInterpolator(self, other, svg).interpolate(fraction)
+
+    def stops_and_orientation(self):
+        """Return a copy of all the stops in this gradient
+
+        .. versionadded:: 1.1"""
+        stops = self.copy()
+        stops.remove_orientation()
+        orientation = self.copy()
+        orientation.remove_all(Stop)
+        return stops, orientation
+
+
+class LinearGradient(Gradient):
+    """LinearGradient element"""
+
+    tag_name = "linearGradient"
+    orientation_attributes = ("x1", "y1", "x2", "y2")
+    """
+    .. versionadded:: 1.1
+    """
+
+    def apply_transform(self):  # type: () -> None
+        """Apply transform to orientation points and set it to identity.
+        .. versionadded:: 1.1
+        """
+        trans = self.pop("gradientTransform")
+        pt1 = (
+            self.to_dimensionless(self.get("x1")),
+            self.to_dimensionless(self.get("y1")),
+        )
+        pt2 = (
+            self.to_dimensionless(self.get("x2")),
+            self.to_dimensionless(self.get("y2")),
+        )
+        p1t = trans.apply_to_point(pt1)
+        p2t = trans.apply_to_point(pt2)
+        self.update(
+            x1=self.to_dimensionless(p1t[0]),
+            y1=self.to_dimensionless(p1t[1]),
+            x2=self.to_dimensionless(p2t[0]),
+            y2=self.to_dimensionless(p2t[1]),
+        )
+
+
+class RadialGradient(Gradient):
+    """RadialGradient element"""
+
+    tag_name = "radialGradient"
+    orientation_attributes = ("cx", "cy", "fx", "fy", "r")
+    """
+    .. versionadded:: 1.1
+    """
+
+    def apply_transform(self):  # type: () -> None
+        """Apply transform to orientation points and set it to identity.
+
+        .. versionadded:: 1.1
+        """
+        trans = self.pop("gradientTransform")
+        pt1 = (
+            self.to_dimensionless(self.get("cx")),
+            self.to_dimensionless(self.get("cy")),
+        )
+        pt2 = (
+            self.to_dimensionless(self.get("fx")),
+            self.to_dimensionless(self.get("fy")),
+        )
+        p1t = trans.apply_to_point(pt1)
+        p2t = trans.apply_to_point(pt2)
+        self.update(
+            cx=self.to_dimensionless(p1t[0]),
+            cy=self.to_dimensionless(p1t[1]),
+            fx=self.to_dimensionless(p2t[0]),
+            fy=self.to_dimensionless(p2t[1]),
+        )
+
+
+class PathEffect(BaseElement):
+    """Inkscape LPE element"""
+
+    tag_name = "inkscape:path-effect"
+
+
+class MeshGradient(Gradient):
+    """Usable MeshGradient XML base class
+
+    .. versionadded:: 1.1"""
+
+    tag_name = "meshgradient"
+
+    @classmethod
+    def new_mesh(cls, pos=None, rows=1, cols=1, autocollect=True):
+        """Return skeleton of 1x1 meshgradient definition."""
+        # initial point
+        if pos is None or len(pos) != 2:
+            pos = [0.0, 0.0]
+        # create nested elements for rows x cols mesh
+        meshgradient = cls()
+        for _ in range(rows):
+            meshrow: BaseElement = meshgradient.add(MeshRow())
+            for _ in range(cols):
+                meshrow.append(MeshPatch())
+        # set meshgradient attributes
+        meshgradient.set("gradientUnits", "userSpaceOnUse")
+        meshgradient.set("x", pos[0])
+        meshgradient.set("y", pos[1])
+        if autocollect:
+            meshgradient.set("inkscape:collect", "always")
+        return meshgradient
+
+
+class MeshRow(BaseElement):
+    """Each row of a mesh gradient
+
+    .. versionadded:: 1.1"""
+
+    tag_name = "meshrow"
+
+
+class MeshPatch(BaseElement):
+    """Each column or 'patch' in a mesh gradient
+
+    .. versionadded:: 1.1"""
+
+    tag_name = "meshpatch"
+
+    def stops(self, edges, colors):
+        """Add or edit meshpatch stops with path and stop-color."""
+        # iterate stops based on number of edges (path data)
+        for i, edge in enumerate(edges):
+            if i < len(self):
+                stop = self[i]
+            else:
+                stop = self.add(Stop())
+
+            # set edge path data
+            stop.set("path", str(edge))
+            # set stop color
+            stop.style["stop-color"] = str(colors[i % 2])