Ink-Annotations not shown

[SimonErm]

Attach (recommended) or Link to PDF file here:
output.pdf

Configuration:

• Web browser and its version: Firefox 88.0
• Operating system and its version: macOS Big Sur 11.2.3 (20D91)
• PDF.js version: 2.8.243
• Is a browser extension: no/Firefox built-in

Steps to reproduce the problem:

1. add Ink-Annotations to a pdf (i use https://github.com/highkite/pdfAnnotate, Annotations with appearance streams are shown correctly)
2. open output file in firefox

What is the expected behavior?
The annotations should be visible.

What went wrong?
The annotations are added to the dom but invisible.

Tested successfull with FoxitReader, AcrobatReader, Chrome and Safari.

[calixteman]

The Ink annotation doesn't contain an appearance so we should build a default one using the color and the Inklist.

[SimonErm]

Thanks for the fast reply.
The Ink annotation is already build, but it's transparent.
If i change the stroke manual from transparent to black it is shown like it should.

[Snuffleupagus]

This is (essentially) just another case of issue #6810.

[calixteman]

We draw the annotation on the canvas using the AP entry and then we use a transparent line in svg to have an object to interact with in the annotation_layer.
Open your pdf here: https://brendandahl.github.io/pdf.js.utils/browser/#root=997,0
and you'll see that no appearance stream (AP) is there.
But if you open https://github.com/mozilla/pdf.js/blob/master/test/pdfs/annotation-caret-ink.pdf in the pdf browser with #root=25,0, you'll see an AP entry with some pdf code to render the line.