Enable zopfli on oxipng

[Csabesz07]

This feature lets the user further optimise the compression of the image by adding new options under oxipng.

• The deflater of oxipng is now selectable (zopfli / libdeflater)
• Both deflater's parameters are modifiable (iterations / compress level)

[jakearchibald]

This is exciting!

[surma]

@Csabesz07 Your code seems to be working :) If you compress a bigger image, the time it take to compress is hugely different although in this case, the compressed file size is almost identical, which is not completely unexpected :D

I’ll do a review in a bit :)

[jakearchibald]

the time it take to compress is hugely different although in this case, the compressed file size is almost identical, which is not completely unexpected :D

I'm not seeing any difference when changing the deflater, or the iterations / compress level setting, which feels a bit sus

[Csabesz07]

I'm not seeing any difference when changing the deflater, or the iterations / compress level setting, which feels a bit sus

Exactly! This is my concern as well, but the way I see, all options are being applied at the moment.
Oxipng documentation mentions that if any of the optimize's options's properties are defined manually, the initial preset options will be overriden with those.

[surma]

I rebuilt the codec locally when testing. I wonder if the binaries on the PR are outdated or something. I’ll take another look tomorrow at that.

[Csabesz07]

Hi @surma
Sorry for the slow follow-up on your change requests. After a busy year, I’m back with full focus. If this feature is still useful for the project, I’d be happy to pick up where we left off and push it forward. What’s the best next step?