canvas2svg

Reminds me of https://github.com/gliffy/canvas2svg at a different level of abstraction. I believe PDF.js incorporated some form canvas2svg to try and get a SVG backend working which would allow high resolution printing to PDF but not sure where that's at. I believe printing through PDF.js is blurry due to memory constraints since with normal canvas pdf pages just end up as bitmaps sent to the printer. SVG ends up staying vector through Chromiums print pipeline resulting in much less memory usage while having much higher dpi final output. I would imagine this is due to SVG being turned into Skia drawing commands that end up as PDF that then gets printed through PDFium?

You can't convert a bitmap back into vectors (well maybe image recognition of some sort). Once you render to canvas its a bitmap and stays that way all the way to printer. SVG is turned into the appropriate PS/PDF vector drawing command by the browser print engine, canvas just gets sent as a bitmap in the printer language since that all that's left. I believe pdf.js incorporated and modified https://github.com/gliffy/canvas2svg which implements the canvas api but instead creates an SVG dom.

Oh! https://github.com/gliffy/canvas2svg

This is just a throw, I've not tried. But Bokeh creates Canvas. There is a Canvas 2 SVG https://github.com/gliffy/canvas2svg JavaScript library already made.