keep history of opened files

[TomTasche]

at the moment we only store URLs of documents a user attempted to open previously. we should conisder copying those documents to our internal cache and show a nice list of them at startup.

[ViliusSutkus89]

Agree on the "show a nice list" part, but I suggest for us to not keep the source files. We already have converted and cached HTMLs, let's just use that.

End user would click on document.odt in the recent documents list and the app would instantly open cached document.odt.html. We could do the same for externally opened documents too, but then we we need to keep a hash of source file, to know if the source file is modified or not.

Not keeping copies of source files moves us closer to the possibility of converting straight from the source, instead of copying to cache and converting from cache. Converting straight from the source implies using android.net.Uri as input, instead of java.io.File . pdf2htmlEX-Android can't handle Uri's yet, but eventually ... ViliusSutkus89/pdf2htmlEX-Android#27 . Copy prevented is time and cache space saved.

[TomTasche]

I suggest for us to not keep the source files

We need the source file for editing. That only applies to ODF (ODT, ODS, ODP, ODG), but that's our main audience.

If it helps we could get rid of java.io.File though and use android.net.Uri instead. The cache already has a valid Uri too.