How to measure cumulative length of selected lines

illiamard

Is there any option to fast measure the cumulative length of selected lines? For example a Serpent Length.
Thank you in advance.
Illia

Matthias

Hi Illia,

Such a function is not available, at least not directly.

But it can be scripted.

Here is a script which employs area and perimeter to approximate a length measure. It is precise for "thin" wires:

# Computes the path length of all selected shapes.
# The path length is approximated from the area and perimeter
# using the following approach:
#
#   p = 2 * w + l1 + l2       (Perimeter)
#   a = w * (l1 + l2) / 2     (Area)
#   -> L = (l1 + l2) / 2 
#        = p / 4 + sqrt(p * p / 16 - a)    (Center length)
# 
# This assumes a thin wire with width w and a left-side length 
# of l1 and a right-side length of l2.

lv = RBA::Application::instance.main_window.current_view
lv || raise("No layout loaded")

selected = RBA::Region::new
cell = nil
ly = nil
dbu = nil
lv.each_object_selected do |s|
  dbu ||= lv.cellview(s.cv_index).layout.dbu
  if !s.is_cell_inst?
    selected.insert(s.shape.polygon)
  end
end

selected.merge

p = selected.perimeter * dbu
a = selected.area * dbu * dbu
l = p / 4 + Math.sqrt(p * p / 16 - a)
RBA::QMessageBox::information(nil, "Approximate Length", "Area #{'%.12g'%a}, Perimeter #{'%.12g'%p} -> Length #{'%.12g'%l}")

Matthias

laurent_c

Then, how to select an highlighted net ?
In next version, will it be possile to script the "highlight net" function ?

Rgds,
Laurent

illiamard

Hi Matthias
Thank you for quick response
Scrip fails for "Big/dense" structures with error:
"bad allocation in Region::merge (class RuntimeError)"
Thanks
Illia

Matthias

Hi Illia,

That means you have really big structures and KLayout runs out of memory.

I guess that on a 32bit installation, KLayout will be able to handle structures as big as several 10M equivalent of rectangles. If you want to go further, you'll have to switch to 64bit and provide enough RAM for that.

But I wonder whether it makes sense to compute line lengths for such structures. Are you sure that is a single wire? The algorithm only works if the structure is a thin wire without branches.

Matthias