How can I export dxf to pdf and keep the entities layered?

[SeanXunIC]

Thank you for developing ezdxf!
I have a question about the pymupdf addon of ezdxf. I want to export the dxf to pdf and keeping the entities’ visibility controlled by layer in pdf, like shown on this figure (the pdf is opened with Acrobat Pro, the layered pdf is exported by AutoCAD DWG to PDF printer):

I tried to export the dxf to pdf by ezdxf and used different strategy but still cannot layer the entities, there seems no layer information in pdf files:

Please refer to my code and the test dxf files:

import pathlib
import ezdxf
from ezdxf.addons.drawing import pymupdf, layout
from ezdxf.math import global_bspline_interpolation
from ezdxf.addons.drawing import Frontend, RenderContext
from ezdxf.addons.drawing.config import (
    Configuration,
    BackgroundPolicy,
    ColorPolicy,
    LineweightPolicy,
)

# Strategy 1: export the modelspace
def export_pdf(dxf_path, scale=1):
    doc = ezdxf.readfile(dxf_path)
    msp = doc.modelspace()
    output_layout = msp

    ezdxf_page = layout.Page(
                0,  # auto-detect
                0,  # auto-detect
                layout.Units.mm,  # 1 drawing unit = 1mm
                layout.Margins.all(0),
                max_width=1189,  # limit page width to 1189mm
                max_height=841,  # limit page height to 841mm
            )
    settings = layout.Settings(scale=scale)

    backend = pymupdf.PyMuPdfBackend()
    config = Configuration(
            background_policy=BackgroundPolicy.WHITE,
            color_policy=ColorPolicy.COLOR,
            lineweight_policy=LineweightPolicy.RELATIVE,
            lineweight_scaling=1,
        )

    Frontend(RenderContext(doc), backend, config=config).draw_layout(output_layout, ezdxf_page)
    pdf_bytes = backend.get_pdf_bytes(ezdxf_page, settings=settings)
    CWD = pathlib.Path("output.pdf")
    CWD.write_bytes(pdf_bytes)


# Strategy 2: seperate the layer to different layout and export
def export_pdf_by_layer(dxf_path, scale=1):
    doc = ezdxf.readfile(dxf_path)
    msp = doc.modelspace()

    ezdxf_page = layout.Page(
                0,  # auto-detect
                0,  # auto-detect
                layout.Units.mm,  # 1 drawing unit = 1mm
                layout.Margins.all(0),
                max_width=1189,  # limit page width to 1189mm
                max_height=841,  # limit page height to 841mm
            )
    settings = layout.Settings(scale=scale)

    backend = pymupdf.PyMuPdfBackend()
    config = Configuration(
            background_policy=BackgroundPolicy.WHITE,
            color_policy=ColorPolicy.COLOR,
            lineweight_policy=LineweightPolicy.RELATIVE,
            lineweight_scaling=1,
        )
    
    for layer in doc.layers:
        layer_name = layer.dxf.name
        new_layout = doc.new_layout(name=layer_name)
        for entity in msp.query(f'*[layer=="{layer_name}"]'):
            new_layout.add_entity(entity)

        Frontend(RenderContext(doc), backend, config=config).draw_layout(new_layout, ezdxf_page)
    
    pdf_bytes = backend.get_pdf_bytes(ezdxf_page, settings=settings)
    CWD = pathlib.Path("output.pdf")
    CWD.write_bytes(pdf_bytes)


def main():
    dxf_path = ".\\test.dxf"
    # export_pdf(dxf_path)
    export_pdf_by_layer(dxf_path)


if __name__ == "__main__":
    main()

And please refer to the attached test files:
dxf and pdf for test.zip
I would like to know what should I do to export the layerd pdf. Thanks again for your attention!

[mbway]

I wasn't aware that PDF has the concept of layers. It looks like what your PDF viewer is calling 'layers' are 'optional content groups'.
MuPDF seems to have support for OCGs. I tried calling doc.get_ocgs() on the document you provided and it lists the same entries that you show in your screenshot.

Currently the ezdxf frontend does not instruct MuPDF to output optional content groups but I think this could be implemented.

[mbway]

This PR should implement what you are looking for 🙂 #1155

[SeanXunIC]

Thank you very much for your updating! This really helped with my question!