From b9fb5042e475f861f9c5bd695d26d70b4195735d Mon Sep 17 00:00:00 2001
From: Mario Voigt <mariovoigt89@t-online.de>
Date: Sun, 23 Aug 2020 03:13:23 +0200
Subject: [PATCH] Added offset paths

---
 extensions/fablabchemnitz_ofsplot.inx | 29 ++++++++++
 extensions/fablabchemnitz_ofsplot.py  | 82 +++++++++++++++++++++++++++
 2 files changed, 111 insertions(+)
 create mode 100644 extensions/fablabchemnitz_ofsplot.inx
 create mode 100644 extensions/fablabchemnitz_ofsplot.py

diff --git a/extensions/fablabchemnitz_ofsplot.inx b/extensions/fablabchemnitz_ofsplot.inx
new file mode 100644
index 00000000..484d825d
--- /dev/null
+++ b/extensions/fablabchemnitz_ofsplot.inx
@@ -0,0 +1,29 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+    <name>Ofsplot (Offset Paths)</name>
+    <id>fablabchemnitz.de.ofsplot</id>
+    <param name="count" type="int" min="0" max="100000" gui-text="Number of offset paths:">10</param>
+    <param name="offset" type="float" min="-1000" max="+1000" gui-text="Offset between two paths:">0.8</param>
+    <param name="init_offset" type="float" min="-1000" max="+1000" gui-text="Initial offset from original path:">0.8</param>
+    <param name="copy_org" type="bool" gui-text="Copy original path (=keep it)">false</param>
+    <param name="offset_increase" type="float" min="-1000" max="+1000" gui-text="Offset increase per iteration:">0.8</param>
+    <param name="miterlimit" type="float" min="0.0" max="1000" gui-text="Miter limit">3.0</param>
+    <param name="clipperscale" type="float" min="0.0" max="9999.0" gui-text="Scaling factor">1024.0</param>
+    <param name="jointype" appearance="combo" type="optiongroup" default="2" gui-text="Join type">
+        <option value="0">Square</option>
+        <option value="1">Round</option>
+        <option value="2">Miter</option>
+    </param>
+    <param name="settingsHelp" type="description">Python library pyclipper needs to be installed. Use Flatten Bezier plugin in advance of this plugin.</param>
+    <effect>
+        <object-type>all</object-type>
+        <effects-menu>
+            <submenu name="FabLab Chemnitz">
+				<submenu name="Shape/Pattern from existing Path(s)"/>
+			</submenu>
+        </effects-menu>
+    </effect>
+    <script>
+        <command location="inx" interpreter="python">fablabchemnitz_ofsplot.py</command>
+    </script>
+</inkscape-extension>
\ No newline at end of file
diff --git a/extensions/fablabchemnitz_ofsplot.py b/extensions/fablabchemnitz_ofsplot.py
new file mode 100644
index 00000000..9bfe840f
--- /dev/null
+++ b/extensions/fablabchemnitz_ofsplot.py
@@ -0,0 +1,82 @@
+#!/usr/bin/env python3
+
+import inkex
+import math
+from inkex.paths import CubicSuperPath
+import re
+import pyclipper
+
+class ofsplot(inkex.Effect):
+    def __init__(self):
+        inkex.Effect.__init__(self)
+        self.arg_parser.add_argument("--count", type=int, default=10, help="Number of offset operations")
+        self.arg_parser.add_argument("--offset", type=float, default=2.0, help="Offset amount")
+        self.arg_parser.add_argument("--init_offset", type=float, default=2.0, help="Initial Offset Amount")
+        self.arg_parser.add_argument("--copy_org", type=inkex.Boolean, default=True, help="copy original path")
+        self.arg_parser.add_argument("--offset_increase", type=float, default=2.0, help="Offset increase between iterations")
+        self.arg_parser.add_argument("--jointype", default="2", help="Join type")
+        self.arg_parser.add_argument("--miterlimit", type=float, default=3.0, help="Miter limit")
+        self.arg_parser.add_argument("--clipperscale", type=float, default=1024.0, help="Scaling factor")
+        
+    def effect(self):
+        paths = self.svg.selection.filter(inkex.PathElement)
+        if len(paths) == 0:
+            inkex.errormsg("No paths selected.")
+            exit()
+        for path in paths:
+            if path.tag == inkex.addNS('path','svg'):
+                p = CubicSuperPath(path.get('d'))
+
+                scale_factor = self.options.clipperscale # 2 ** 32 = 1024 - see also https://github.com/fonttools/pyclipper/wiki/Deprecating-SCALING_FACTOR
+
+                pco = pyclipper.PyclipperOffset(self.options.miterlimit)
+                
+                JT = pyclipper.JT_MITER
+                if self.options.jointype == "0":
+                    JT = pyclipper.JT_SQUARE
+                elif self.options.jointype == "1":
+                    JT = pyclipper.JT_ROUND
+                elif self.options.jointype == "2":
+                    JT = pyclipper.JT_MITER     
+                new = []
+
+                # load in initial paths
+                for sub in p:
+                    sub_simple = []
+                    for item in sub:
+                        itemx = [float(z)*scale_factor for z in item[1]]
+                        sub_simple.append(itemx)
+                    pco.AddPath(sub_simple, JT, pyclipper.ET_CLOSEDPOLYGON)
+
+                # calculate offset paths for different offset amounts
+                offset_list = []
+                offset_list.append(self.options.init_offset)
+                for i in range(0,self.options.count+1):
+                    ofs_inc = +math.pow(float(i)*self.options.offset_increase,2)
+                    if self.options.offset_increase <0:
+                        ofs_inc = -ofs_inc
+                    offset_list.append(offset_list[0]+float(i)*self.options.offset+ofs_inc)
+
+                solutions = []
+                for offset in offset_list:
+                    solution = pco.Execute(offset * scale_factor)
+                    solutions.append(solution)
+                    if len(solution)<=0:
+                        continue # no more loops to go, will provide no results.
+
+                # re-arrange solutions to fit expected format & add to array
+                for solution in solutions:
+                    for sol in solution:
+                        solx = [[float(s[0]) / scale_factor, float(s[1]) / scale_factor] for s in sol]
+                        sol_p = [[a,a,a] for a in solx]
+                        sol_p.append(sol_p[0][:])
+                        new.append(sol_p)
+
+                # add old, just to keep (make optional!)
+                if self.options.copy_org:
+                    for sub in p:
+                        new.append(sub)
+
+                path.set('d',CubicSuperPath(new))
+
+ofsplot().run()
\ No newline at end of file