Fix bounding box edge cases (#164)

* fixes case where cell is full of references which yield no valid polygons or bounding boxes and ends up returning initialization value * test case 7b will cause master to fail but this fixed version will pass * removing top if statement and making the code more readable. changing extend to append when adding ref bboxes * caching the bbox=None case Co-authored-by: Troy Tamas <[email protected]>
heitzmann · Dec 23, 2020 · 16c7012 · 16c7012
2 parents 3a86422 + c4232c6
commit 16c7012
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Showing 2 changed files with 33 additions and 15 deletions.
diff --git a/gdspy/library.py b/gdspy/library.py
@@ -559,15 +559,9 @@ def get_bounding_box(self):
             Bounding box of this cell [[x_min, y_min], [x_max, y_max]],
             or None if the cell is empty.
         """
-        if (
-            len(self.polygons) == 0
-            and len(self.paths) == 0
-            and len(self.references) == 0
-        ):
-            return None
-        if not (
-            self._bb_valid and all(ref._bb_valid for ref in self.get_dependencies(True))
-        ):
+        deps_still_valid = all(ref._bb_valid for ref in self.get_dependencies(True))
+        cached_bbox_still_valid = self._bb_valid and deps_still_valid
+        if not cached_bbox_still_valid:
             bb = numpy.array(((1e300, 1e300), (-1e300, -1e300)))
             all_polygons = []
             for polygon in self.polygons:
@@ -577,19 +571,23 @@ def get_bounding_box(self):
             for reference in self.references:
                 reference_bb = reference.get_bounding_box()
                 if reference_bb is not None:
-                    bb[0, 0] = min(bb[0, 0], reference_bb[0, 0])
-                    bb[0, 1] = min(bb[0, 1], reference_bb[0, 1])
-                    bb[1, 0] = max(bb[1, 0], reference_bb[1, 0])
-                    bb[1, 1] = max(bb[1, 1], reference_bb[1, 1])
+                    all_polygons.append(reference_bb)
             if len(all_polygons) > 0:
                 all_points = numpy.concatenate(all_polygons).transpose()
                 bb[0, 0] = min(bb[0, 0], all_points[0].min())
                 bb[0, 1] = min(bb[0, 1], all_points[1].min())
                 bb[1, 0] = max(bb[1, 0], all_points[0].max())
                 bb[1, 1] = max(bb[1, 1], all_points[1].max())
+                self._bounding_box = bb
+            else:
+                self._bounding_box = None
             self._bb_valid = True
-            self._bounding_box = bb
-        return numpy.array(self._bounding_box)
+
+        if self._bounding_box is None:
+            return None
+        else:
+            # return a *copy* of the cached bounding box to ensure it doesn't get inadvertently modified
+            return numpy.array(self._bounding_box)
 
     def get_polygons(self, by_spec=False, depth=None):
         """

diff --git a/tests/cell.py b/tests/cell.py
@@ -293,6 +293,26 @@ def test_bounding_box():
 
     assert_bb(cell6.get_bounding_box(), ((2, 0), (3, 1)))
 
+    cell7a = gdspy.Cell("7a")
+
+    assert cell7a.get_bounding_box() is None
+
+    cell7b = gdspy.Cell("7b")
+    cell7b.add(gdspy.CellReference(cell7a, rotation=90))
+
+    assert cell7b.get_bounding_box() is None
+
+    cell7c = gdspy.Cell("7c")
+    cell7c.add(gdspy.CellReference(cell7b))
+
+    assert cell7c.get_bounding_box() is None
+
+    cell7 = gdspy.Cell("7")
+    cell7.add(cell1)
+    cell7.add(cell7c)
+
+    assert_bb(cell7.get_bounding_box(), ((0, 0), (1, 1)))
+
 
 def test_bounding_box2():
     cell0 = gdspy.Cell("0")