Rework outline reconstruciton to be reliable

- This is a backport of a7088f5

pcbdraw/pcbdraw.py

@@ -144,6 +144,13 @@ def unique_prefix():
 def matrix(data):
     return np.array(data, dtype=np.float32)
 
+def pseudo_distance(a, b):
+    return (a[0] - b[0])**2 + (a[1] - b[1])**2
+
+def get_closest(reference, elems):
+    distances = [pseudo_distance(reference, x) for x in elems]
+    return np.argmin(distances)
+
 def extract_arg(args, index, default=None):
     """
     Return n-th element of array or default if out of range
@@ -412,23 +419,36 @@ def get_board_polygon(svg_elements):
         elements = elements[1:]
         size = 0
         # Append new segments to the ends of outline until there is none to append.
-        while size != len(outline):
+        while size != len(outline) and len(elements) > 0:
             size = len(outline)
-            for i, e in enumerate(elements):
-                if SvgPathItem.is_same(outline[0].start, e.end):
-                    outline.insert(0, e)
-                elif SvgPathItem.is_same(outline[0].start, e.start):
-                    e.flip()
-                    outline.insert(0, e)
-                elif SvgPathItem.is_same(outline[-1].end, e.start):
-                    outline.append(e)
-                elif SvgPathItem.is_same(outline[-1].end, e.end):
-                    e.flip()
-                    outline.append(e)
-                else:
-                    continue
+
+            i = get_closest(outline[0].start, [x.end for x in elements])
+            if SvgPathItem.is_same(outline[0].start, elements[i].end):
+                outline.insert(0, elements[i])
+                del elements[i]
+                continue
+
+            i = get_closest(outline[0].start, [x.start for x in elements])
+            if SvgPathItem.is_same(outline[0].start, elements[i].start):
+                e = elements[i]
+                e.flip()
+                outline.insert(0, e)
                 del elements[i]
-                break
+                continue
+
+            i = get_closest(outline[-1].end, [x.start for x in elements])
+            if SvgPathItem.is_same(outline[-1].end, elements[i].start):
+                outline.insert(0, elements[i])
+                del elements[i]
+                continue
+
+            i = get_closest(outline[-1].end, [x.end for x in elements])
+            if SvgPathItem.is_same(outline[-1].end, elements[i].end):
+                e = elements[i]
+                e.flip()
+                outline.insert(0, e)
+                del elements[i]
+                continue
         # ...then, append it to path.
         first = True
         for x in outline: