Add support for exporting annotated pdfs

[kayceesrk]

Exporting annotated pdfs through the native apps is broken since the native export functionality does not account for the different page sizes between the tablet and the pdf. The PR introduces a script exportDocument to export the PDF and correct for the page sizes. Moreover, the exported pdf is not a bitmap unlike the native export functionality and retains the vector graphics. Hence, the exported pdf remains selectable and searchable.

---

Exporting natively using the Mac app:

Export using exportDocument:

[florian-wagner]

Hi @kayceesrk,

thanks for your contribution! I like the granular scale height and width functions. However, this PR introduces some redundancy as it neglects the fact that exportNotebook also exports documents (and corrects page sizes if they are A4, see also PRs #7 and #12). It also has optional color support as shown here: https://github.com/reHackable/maxio/files/1695105/remarkable-c.pdf

I am not quite sure how we proceed and I am curious what @edupont and @Ameb think. I am pro granularity and against redundancy. Ideally one would have:

• A high-level exportPDF function, which calls a:
  • a transfer function: Handles all the ssh things, copies to a temp folder irrespective of the file being a notebook or a document
  • a lines2PDF function which calls rm2SVG and converts the foreground to PDF (with optional color support), after that either of the two scripts are called
    • a) templates2PDF: which checks the used templates and puts them to a background PDF
    • b) scaleBackground: which is called if a background PDF exists and which corrects for the page size of the original pdf

and finally the exportPDF function would call pdftk multistamp to put foreground and background together and delete the temp folder.

What do you guys think?

[kayceesrk]

Thanks @florian-wagner. I hadn't realised exportNotebook also corrected for sizes. It might be best to break up the functionality into smaller scripts as you have proposed to avoid redundancy.