Validity of bounding box after cell deep copy

[okianus]

gdspy.Cell.copy() provides the ability to create a deep copy of a cell. It was noticed that when this is done for nested cells, any CellReferences within the cell have a their _bb_valid flags set to True. Hence, if you perform a deep copy of a cell, and then try to get its bounding box using get_bounding_box(), the algorithm fails, generating a KeyError at the return statement of gdspy.Cell.get_bounding_box() method.

I do not know all the implications of this, but at the very least, I believe the _bb_valid flags for the dependencies have to be explicitly set to False within cell.copy() to allow recalculation of the bounding boxes:

for ref in new_cell.get_dependencies(True):
            if ref._bb_valid:
                print('Reference ' + str(ref) + ' bb_valid flag is True, set to False')
                ref._bb_valid = False

[heitzmann]

Hi @okianus,

I believe your solution is correct, but I have to take a look into any side-effects that could be involved.

I'm quite dissatisfied with the current state of the bounding box logic because of those side-effects. For instance, if the bounding box is calculated and then a change is made in the internal array of points of any polygon, the bounding box of any cells involved will not reflect it... I guess that's the price we pay for caching the values.

[heitzmann]

Fixed in 2dd4557
Thank you for the bugfix!