Use OS-standard method to save and load files (Qt or other)

[Semphriss]

Currently, Annotate uses a basic Python command that runs a CGI server that the webapp can connect to, and that CGI server handles the files.

This is ugly for several reasons:

• Running that Python code requires full access to the system to access the necessary modules.
• The CGI server has a problem where it will read data indefinitely, resulting in the bug documented at www/js/file_manager.mjs in the action function. (reference commit: 09fd270) This forces the user to wait exactly 1 second each time a file is saved.
• The security is bad.
• The code is only as stable as a Bash script can get.

The most likely replacement would be a QtWebView, unfortunately I am not even remotely familiar enough with Qt to implement the replacement.

I open this issue in the hopes that someone more experienced than me could provide some help there. If someone wants to give it a try, the only modifications needed should be in www/js/file_manager.mjs (and deleting the cgi-bin folder).

[Semphriss]

With 7904bbe, I've replaced the Python script with a custom C++ webserver. It removes the need for unconfined mode and the read-indefinitely bug, but the security is just as bad (if not worse) and probably quite inconvenient to maintain.

[raboof]

I'm very new to the Ubuntu Touch ecosystem, but I wonder if it'd be possible to use HTML5 File APIs for that? A really quick and crude test at #14 seems at least promising - are there known limitations to that approach?

Ah, I did not realize that this issue is not so much about the 'Load PDF' functionality, but about allowing other apps to do 'open PDF with Annotate' and vice-versa