Design size variation when using Save layout options

jonathan

Hello,

I have a design "test.oas" with a top cell that interest me "Top" and a bunch of other empty topcells.
I try to get rid of other topcells using SaveLayoutOptions, but I am then getting a very large design

if I run the following script:

ly=pya.Layout()
ly.read("test.oas")
lo = pya.SaveLayoutOptions()
lo.add_cell(ly.cell("Top").cell_index())
ly.write("test2.oas",lo)
ly.clear()
ly.read("test2.oas")
ly.write("test3.oas")

I have the following design sizes:
test.oas is 199K
test2.oas is 31M (too large file!)
test3.oas is 174K (what I was hoping to have)

I also tried to change oasis compression level

lo.oasis_compression_level = 10

but it did not change anything.
would you have any idea what I am doing wrong when using Save layout options?

Matthias

Hi @jonathan,

"test2.oas" is not an OASIS file, because the default format is "GDS2" in "SaveLayoutOptions". Use "set_format_from_filename" to establish the right format (https://www.klayout.de/doc-qt5/code/class_SaveLayoutOptions.html#k_88).

Matthias

jonathan

Thanks! This has solved the issue!

also providing corrected code:

ly=pya.Layout()
ly.read("test.oas")
lo = pya.SaveLayoutOptions()
lo.add_cell(ly.cell("Top").cell_index())
lo.set_format_from_filename("test2.oas")
ly.write("test2.oas",lo)

test2.oas is 174K

I have noticed that if I use

lo.set_format_from_filename("file.oas")  

It also works, so it is not necessary to have the same name as the output file, however

lo.set_format_from_filename(".oas")

fails and cannot determine the format, but I think it could be a good upgrade to allow this?

PS:
I also noted the other solution:

lo.format= "OASIS"

and sorry for not reading API reference properly as the format info is quite well documented.