1 files changed, 79 insertions, 0 deletions
diff --git a/share/extensions/inkex/tween.py b/share/extensions/inkex/tween.py
new file mode 100644
index 0000000..31c165b
--- /dev/null
+++ b/share/extensions/inkex/tween.py
@@ -0,0 +1,79 @@
+# coding=utf-8
+#
+# Copyright (C) 2005 Aaron Spike, aaron@ekips.org
+#
+# 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.
+#
+
+import math
+
+from bisect import bisect_left
+from .utils import X, Y
+from .units import convert_unit, parse_unit, render_unit
+
+try:
+    from typing import Union, Tuple, List, TypeVar, Callable, overload
+    hasTypes = True
+    Value = TypeVar('Value')
+    Number = TypeVar('Number', int, float)
+except ImportError:
+    pass
+
+
+def interpcoord(
+    coord_a, # type: Number 
+    coord_b, # type: Number 
+    time # type: float
+):
+    # type: (...) -> float 
+    """Interpolate single coordinate by the amount of time"""
+    return coord_a + ((coord_b - coord_a) * time)
+
+
+def interp(
+    positions, # type: List[float]
+    values, # type: List[Value]
+    newpositions, # type: List[float]
+    func # type: (Callable[[Value, Value, float], Value])
+):
+    # type: (...) -> List[Value]
+    """Interpolate list with arbitrary interpolation function."""
+    newvalues = []
+    positions = list(map(float, positions))
+    newpositions = list(map(float, newpositions))
+    for pos in newpositions:
+        idxl = max(0, bisect_left(positions, pos) - 1)
+        idxr = min(len(positions)-1, idxl + 1)
+        fraction = (pos - positions[idxl]) / (positions[idxr] - positions[idxl])
+        vall = values[idxl]
+        valr = values[idxr]
+        newval = func(vall, valr, fraction)
+        newvalues.append(newval)
+    return newvalues
+
+
+def interppoints(point1, point2, time):
+    # type: (Tuple[float, float], Tuple[float, float], float) -> Tuple[float, float]
+    """Interpolate coordinate points by amount of time"""
+    return (interpcoord(point1[X], point2[X], time), interpcoord(point1[Y], point2[Y], time))
+
+
+def interpunit(start, end, fraction):
+    # type: (str, str, float) -> str
+    """Interpolate float attributes with unit."""
+    # moved here so we can call 'unittouu'
+    sp, unit = parse_unit(start)
+    ep = convert_unit(end, unit)
+    return render_unit(interpcoord(sp, ep, fraction), unit)