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from gerbonara import *
from shapely import *
stack = layers.LayerStack.open('/home/jaseg/proj/ihsm-strain-gage-controller-hw/pcb/gerber')
# Let's work in mm here. Gerbonara will take care to convert units when the file is in US customary units.
(x1, y1), (x2, y2) = stack.bounding_box(unit=utils.MM)
for l in [stack['bottom mask'], stack['top mask']]:
# The solder mask gerber layer by convention is "negative". That is, a "dark" polarity (drawn) Gerber primitive
# will result in an opening in the solder mask. Conversely, an empty gerber file would lead to the entire board
# being covered in solder mask.
#
# Here, we add a rectangle covering the entire board so the entire board is *free* of solder mask.
new = [graphic_objects.Region(
[(x1, y1), (x1, y2), (x2, y2), (x2, y1), (x1, y1)],
unit=utils.MM,
polarity_dark=True)]
# Iterate through all objects on the solder mask layer. In later KiCad versions, everything on the solder mask
# layer is exported as a Gerber region, which is a really bad idea, but makes things easy for us here.
for obj in l.objects:
if not obj.polarity_dark:
continue
if isinstance(obj, graphic_objects.Region):
regions = []
else:
regions = [graphic_objects.Region.from_arc_poly(prim.to_arc_poly())
for prim in obj.to_primitives(unit=utils.MM)]
for obj in regions:
# Convert the region to a shapely line string
ls = LineString(obj.outline).normalize()
# Ask shapely to offset the line string by 1 mm
out = ls.offset_curve(obj.unit(1, 'mm'))
# For negative offsets, this operation can result in an object being split up into multiple parts, so we
# might get back a MultiLineString instead of a LineString.
for ls in (out.geoms if hasattr(out, 'geoms') else [out]):
# Convert the resulting shapely object back to a Gerber region.
new.append(graphic_objects.Region(
unit=obj.unit,
polarity_dark=not obj.polarity_dark,
outline=list(ls.coords)))
# Append the new objects to the original layer data
l.objects = new + l.objects
# Write the modified layer stack to a new Gerber directory
stack.save_to_directory('/tmp/out')
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