Ruby/Python binding for "unround" feature

[klayoutmatthias]

The "unround" feature is the basis of the capability to "edit" corner radii of polygons. The C++ function is "extract_rad" from dbPolygonTools.h. A Ruby/Python binding is asked to make this function accessible to scripts.

The proposed binding is:

polygon = ... # some RBA::Polygon or RBA::DPolygon
(new_polygon, outer_radius, inner_radius, n) = polygon.extract_rad

The result will be:

• new_polygon: a polygon representing the "unrounded" (corner rounding removed) version of the original polygon.
• outer_radius: the outer radius detected from the polygon
• inner_radius: the inner corner radius detected from the polygon
• n: the number of vertex points per full circle detected from the original polygon

So basically

new_polygon.round_corners(outer_radius, inner_radius, n)

will (more or less) render the original polygon.

[klayoutmatthias]

I addition what is mentioned in the ticked, there now also are DPolygon#round_corners, DSimplePolygon#round_corners methods.

[klayoutmatthias]

This is how you can use the feature in DRC

class DRC::DRCLayer
  def change_radius(ri, ro, n)
    res = []
    self.data.each do |p|
      x = p.extract_rad
      if x.empty?
        res << p
      else
        res << x[0].round_corners(ri / @engine.dbu, ro / @engine.dbu, n)
      end
    end
    return DRC::DRCLayer::new(@engine, RBA::Region::new(res))
  end
end

org = input(24)

# Apply 1 (inner) and 2 (outer) corner rounding with 100 points/circle
org_r1 = org.rounded_corners(1.um, 2.um, 100)
org_r1.output(1000)

# Change that to 2/3/200 
org_r2 = org_r1.change_radius(2.um, 3.um, 200)
org_r2.output(1001)