How to duplicate ‘/Root’, except ‘/Metadata’, from PdfReader to PdfWriter?

[macdeport]

create_viewer_preferences() exists, but how do you define these preferences?

[pubpub-zz]

https://pypdf.readthedocs.io/en/stable/user/viewer-preferences.html?highlight=create_viewer_preferences

[macdeport]

@pubpub-zz Thank you.

But in fact I have to clone PdfReader viewer_preferences in PdfWriter: what is the best way to do?

More generally I try to duplicate ‘/Root’, except ‘/Metadata’, from PdfReader to PdfWriter.

[pubpub-zz]

if you want just viewer_preference from reader, You should use:
writer.root_object[pypdf.generic.NameObject("/ViewerPreferences")] = reader.root_object["/ViewerPreferences"].clone(writer)

[macdeport]

if you want just viewer_preference from reader, You should use:
writer.root_object[pypdf.generic.NameObject("/ViewerPreferences")] = reader.root_object["/ViewerPreferences"].clone(writer)

Works like a charm, even slightly modified:

from pypdf import generic,PdfReader, PdfWriter

reader = PdfReader(pdf_in_path); writer = PdfWriter(pdf_out_path)
writer.root_object[generic.NameObject('/ViewerPreferences')] = reader.viewer_preferences

@pubpub-zz Thank you

PS: Your answer works perfectly without .clone(writer)