Better zipping

[zwim]

This gives about 1Meg smaller apk.
Compression time on a quad-core is about twice as zip -r9, when using mx=7 its about the same time (of course then the compression is not as good, but saves 800k)
Decompression memory usage does not seem to be bigger: Tested with grep grep VmPeak /proc/$PID/status and grep VmHWM /proc/$PID/status showed almost identical values.

I have used this compression the last weeks on Tolino and phone without strange effects.

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This change is 

[pazos]

Looks cool. An alternative to save a few MB would be https://commons.apache.org/proper/commons-compress/examples.html. and switch back to xz compression.

[Frenzie]

Is 7z available on F-Droid?

[pazos]

Is 7z available on F-Droid?

@licaon-kter ^^. Can we assume that the build machine has 7z binary installed?

Also, for future proof, it is ok to have this artifact as a dependency: https://mvnrepository.com/artifact/org.apache.commons/commons-compress ?

[licaon-kter]

If Debian Stretch (for now) has it...

I'd go with xz though, as 7zip is soo old. But whatever you want.

[zwim]

I'd go with xz though, as 7zip is soo old. But whatever you want.

zip is even older!

I would have no problems with xz. In fact I would prefer it.
But there was a discussion #5264 (almost exact one year ago). I did not get the point, why KOReader moved to zip.

By the way. Using 7z for zip-file creation might be less invasive than switching to xz, my 5ct.

[licaon-kter]

I meant old as in stuck at version 16 and no newer source code.

[pazos]

But there was a discussion #5264 (almost exact one year ago). I did not get the point, why KOReader moved to zip

Because ZipInputStream is part of java/android libraries. That makes possible to catch errors uncompressing, which was not possible using 7z via ffi. It should be a matter of replacing the offending function with an updated one using apache common compress artifact. See https://github.com/koreader/android-luajit-launcher/blob/master/app/src/org/koreader/launcher/utils/AssetsUtils.kt#L101-L151