PolyLine annotation is not visible

[femtozer]

I'm trying to add a polyline annotation to a pdf file. It does not work whether it is an existing file or a new file (add_blank_page).

Environment

Which environment were you using when you encountered the problem?

$ python -m platform
macOS-12.6.1-arm64-arm-64bit

$ python -c "import pypdf;print(pypdf.__version__)"
3.8.0

Code + PDF

This is a minimal, complete example that shows the issue:

from pypdf import PdfWriter
from pypdf.generic import AnnotationBuilder

writer = PdfWriter()
writer.add_blank_page(200, 200)

annotation = AnnotationBuilder.polyline(
    vertices=[
        (50, 50),
        (50, 150),
        (150, 150),
        (150, 50),
        (50, 50),
    ],
)
writer.add_annotation(page_number=0, annotation=annotation)

with open("output.pdf", "wb") as f:
    writer.write(f)

The output pdf file is empty: output.pdf

[MartinThoma]

Please share the output of "pdfly pagemeta" https://pypi.org/project/pdfly/ of the first page of that document

[femtozer]

                output.pdf, page index 0                 
┏━━━━━━━━━━━━━┳━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┓
┃   Attribute ┃ Value                                   ┃
┡━━━━━━━━━━━━━╇━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━┩
│    mediabox │ (0, 0, 200, 200): with=200 x height=200 │
│     cropbox │ (0, 0, 200, 200): with=200 x height=200 │
│      artbox │ (0, 0, 200, 200): with=200 x height=200 │
│    bleedbox │ (0, 0, 200, 200): with=200 x height=200 │
│ annotations │ 1                                       │
└─────────────┴─────────────────────────────────────────┘
All annotations:                                                    
1. /PolyLine at [50, 50, 50, 50]

[pubpub-zz]

If you look at the pdf, you will see the polyline. To make it visible change the color. The problem is just the default color. Set it to red ie. ArrayObject(FloatObject(1.0),FloatObject(0.0),FloatObject(0.0)) and it should be good

[MartinThoma]

Interesting, I would have thought that black is the default color.

Here is a complete example:

from pypdf import PdfWriter
from pypdf.generic import AnnotationBuilder, NameObject, FloatObject, ArrayObject

writer = PdfWriter()
writer.add_blank_page(200, 200)

annotation = AnnotationBuilder.polyline(
    vertices=[
        (50, 50),
        (50, 150),
        (150, 150),
        (150, 50),
        (50, 50),
    ],
)

# Change the border color of the PolyLine:
annotation[NameObject("/C")] = ArrayObject(
    [FloatObject(0.9), FloatObject(0.1), FloatObject(0)]
)
writer.add_annotation(page_number=0, annotation=annotation)

with open("output.pdf", "wb") as f:
    writer.write(f)

From the specs:

[femtozer]

It seems that the problem is on the side of the visualization of the pdf on Mac. I don't see the annotation using either Preview or Chrome, but I do see it using an online pdf reader.

[MartinThoma]

Is the new code I shared also causing those issues or is it just the old code?

[femtozer]

The code you shared did not solve the issue. If that helps, I also tried with the rectangle annotation and had a better result:

from pypdf import PdfWriter
from pypdf.generic import AnnotationBuilder

writer = PdfWriter()
writer.add_blank_page(200, 200)

# Add the rectangle
annotation = AnnotationBuilder.rectangle(
    rect=(50, 150, 150, 50),
)
writer.add_annotation(page_number=0, annotation=annotation)


with open("output.pdf", "wb") as f:
    writer.write(f)

The generated pdf has a visible annotation on Chrome but not on Preview (which seems to be known for poor annotation support).

[pubpub-zz]

if the issue in on Preview, I think we can close this issue

[MartinThoma]

Let's leave it open to either document the color-thing or change the default value (which is blocked by the annotation PR https://github.com/py-pdf/pypdf/pull/1745). This will be pretty easy to close once the annotation PR is merged (I now hope for mid of May)