Added Sieve extension

extensions/fablabchemnitz_sieve.inx

@@ -0,0 +1,23 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<inkscape-extension xmlns="http://www.inkscape.org/namespace/inkscape/extension">
+    <_name>Small Area Filter</_name>
+    <id>fablabchemnitz.de.small_area_filter</id>
+    <param name="use" type="description" xml:space="preserve">Paths with area smaller than the given area threshold will be deleted</param>
+    <param name="unit" _gui-text="Unit" type="enum">
+        <_item value="mm">mm^2</_item>
+        <_item value="cm">cm^2</_item>
+        <_item value="m">m^2</_item>
+    </param>
+    <param name="area" type="float" min="0.0" max="10000000.0" _gui-text="Area (Unit^2):">1.0</param>
+    <effect>
+        <object-type>all</object-type>
+        <effects-menu>
+            <submenu _name="FabLab Chemnitz">
+                <submenu _name="Nesting/Cut Optimization" />
+            </submenu>
+        </effects-menu>
+    </effect>
+    <script>
+        <command reldir="extensions" interpreter="python">fablabchemnitz_sieve.py</command>
+    </script>
+</inkscape-extension>

extensions/fablabchemnitz_sieve.py

@@ -0,0 +1,43 @@
+#!/usr/bin/env python3
+
+import inkex
+import svgpathtools
+
+def isclosedac(p):
+    return abs(p.start-p.end) < 1e-6
+
+
+class Sieve(inkex.Effect):
+    def __init__(self):
+        inkex.Effect.__init__(self)
+        self.arg_parser.add_argument('--unit')
+        self.arg_parser.add_argument('--area', type=float, help='Remove paths with an area smaller than this value')
+		
+    def effect(self):
+        namedView = self.document.getroot().find(inkex.addNS('namedview', 'sodipodi'))
+        doc_units = namedView.get(inkex.addNS('document-units', 'inkscape'))
+        #inkex.utils.debug("document unit is " + doc_units)
+        self.options.area = self.svg.unittouu(str(self.options.area) + doc_units)
+        unit_factor = 1.0 / self.svg.uutounit(1.0,self.options.unit)
+        #inkex.utils.debug("unit_factor is " + str(unit_factor))
+		
+        if self.options.area == 0:
+            return
+
+        for path in self.document.xpath("//svg:path", namespaces=inkex.NSS):
+            try:
+                parsed_path = svgpathtools.parse_path(path.attrib["d"])
+                
+                if not isclosedac(parsed_path):
+                    continue
+                
+                area = parsed_path.area()
+                #inkex.utils.debug(area) #print calculated area with document units
+                #inkex.utils.debug(str(self.options.area * (unit_factor * unit_factor))) #print threshold area with selected units
+                if area < (self.options.area * (unit_factor * unit_factor)):
+                    path.getparent().remove(path)
+            except:
+                pass
+
+if __name__ == '__main__':
+    Sieve().run()