1 files changed, 144 insertions, 0 deletions
diff --git a/share/extensions/inkex/elements/_utils.py b/share/extensions/inkex/elements/_utils.py
new file mode 100644
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+++ b/share/extensions/inkex/elements/_utils.py
@@ -0,0 +1,144 @@
+# -*- coding: utf-8 -*-
+#
+# Copyright (c) 2021 Martin Owens <doctormo@gmail.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.
+#
+"""
+Useful utilities specifically for elements (that aren't base classes)
+
+.. versionadded:: 1.1
+    Most of the methods in this module were moved from inkex.utils.
+"""
+
+from collections import defaultdict
+import re
+
+# a dictionary of all of the xmlns prefixes in a standard inkscape doc
+NSS = {
+    "sodipodi": "http://sodipodi.sourceforge.net/DTD/sodipodi-0.dtd",
+    "cc": "http://creativecommons.org/ns#",
+    "ccOLD": "http://web.resource.org/cc/",
+    "svg": "http://www.w3.org/2000/svg",
+    "dc": "http://purl.org/dc/elements/1.1/",
+    "rdf": "http://www.w3.org/1999/02/22-rdf-syntax-ns#",
+    "inkscape": "http://www.inkscape.org/namespaces/inkscape",
+    "xlink": "http://www.w3.org/1999/xlink",
+    "xml": "http://www.w3.org/XML/1998/namespace",
+}
+SSN = dict((b, a) for (a, b) in NSS.items())
+
+
+def addNS(tag, ns=None):  # pylint: disable=invalid-name
+    """Add a known namespace to a name for use with lxml"""
+    if tag.startswith("{") and ns:
+        _, tag = removeNS(tag)
+    if not tag.startswith("{"):
+        tag = tag.replace("__", ":")
+        if ":" in tag:
+            (ns, tag) = tag.rsplit(":", 1)
+        ns = NSS.get(ns, None) or ns
+        if ns is not None:
+            return f"{{{ns}}}{tag}"
+    return tag
+
+
+def removeNS(name):  # pylint: disable=invalid-name
+    """The reverse of addNS, finds any namespace and returns tuple (ns, tag)"""
+    if name[0] == "{":
+        (url, tag) = name[1:].split("}", 1)
+        return SSN.get(url, "svg"), tag
+    if ":" in name:
+        return name.rsplit(":", 1)
+    return "svg", name
+
+
+def splitNS(name):  # pylint: disable=invalid-name
+    """Like removeNS, but returns a url instead of a prefix"""
+    (prefix, tag) = removeNS(name)
+    return (NSS[prefix], tag)
+
+
+def natural_sort_key(key, _nsre=re.compile("([0-9]+)")):
+    """Helper for a natural sort, see
+    https://stackoverflow.com/a/16090640/3298143"""
+    return [int(text) if text.isdigit() else text.lower() for text in _nsre.split(key)]
+
+
+class ChildToProperty(property):
+    """Use when you have a singleton child element who's text
+    content is the canonical value for the property"""
+
+    def __init__(self, tag, prepend=False):
+        super().__init__()
+        self.tag = tag
+        self.prepend = prepend
+
+    def __get__(self, obj, klass=None):
+        elem = obj.findone(self.tag)
+        return elem.text if elem is not None else None
+
+    def __set__(self, obj, value):
+        elem = obj.get_or_create(self.tag, prepend=self.prepend)
+        elem.text = value
+
+    def __delete__(self, obj):
+        obj.remove_all(self.tag)
+
+    @property
+    def __doc__(self):
+        return f"Get, set or delete the {self.tag} property."
+
+
+class CloningVat:
+    """
+    When modifying defs, sometimes we want to know if every backlink would have
+    needed changing, or it was just some of them.
+
+    This tracks the def elements, their promises and creates clones if needed.
+    """
+
+    def __init__(self, svg):
+        self.svg = svg
+        self.tracks = defaultdict(set)
+        self.set_ids = defaultdict(list)
+
+    def track(self, elem, parent, set_id=None, **kwargs):
+        """Track the element and connected parent"""
+        elem_id = elem.get("id")
+        parent_id = parent.get("id")
+        self.tracks[elem_id].add(parent_id)
+        self.set_ids[elem_id].append((set_id, kwargs))
+
+    def process(self, process, types=(), make_clones=True, **kwargs):
+        """
+        Process each tracked item if the backlinks match the parents
+
+        Optionally make clones, process the clone and set the new id.
+        """
+        for elem_id in list(self.tracks):
+            parents = self.tracks[elem_id]
+            elem = self.svg.getElementById(elem_id)
+            backlinks = {blk.get("id") for blk in elem.backlinks(*types)}
+            if backlinks == parents:
+                # No need to clone, we're processing on-behalf of all parents
+                process(elem, **kwargs)
+            elif make_clones:
+                clone = elem.copy()
+                elem.getparent().append(clone)
+                clone.set_random_id()
+                for update, upkw in self.set_ids.get(elem_id, ()):
+                    update(elem.get("id"), clone.get("id"), **upkw)
+                process(clone, **kwargs)