Apply filter on picture taken

[rawbertp]

Instead of selecting a filter before taking the picture (without even knowing what the filter result is going to look like!), allow the users to apply the filter after the picture was taken. The selected filter will be applied immediately.

Fixes/addresses: #190 ( #96 )

Further improvements/next steps (but not necessarily as part of this PR):

• Present a tiny preview ("on hover") showing what the filter result looks like
• Use IMagick and implement "nicer" filters

@sualko @andi34 I have set this to WIP as there are some minor bits and pieces missing but you can already review it if you want to.

[sualko]

I like the idea to choose the filter afterwards and I think there are just some ui things we have to revisit. The current filter list doesn't look that good as overlay, but I assume this was just a proof of concept. If you have time it would be great if you could finalize this pr.

Further improvements/next steps (but not necessarily as part of this PR)

Would love to see this in a second pr, so that we can merge your enhancement asap.

[andi34]

Thanks for the nice work!

I've already rebased it here which can be picked once #206 and maybe #205 was merged:
andi34@5d4c3da

Works fine for me (only had time to test in dev mode),
i've put your README formatting changes here already: #206 .

Changing the Filtermenu , adding preview on hover and reworking filters to use Imagemagick (not sure if a pi is the best device for imagemagick, was quite slow once i tested) could be done in seperate PR's.

[andi34]

@rawbertp could you please rebase on latest master branch? ( andi34@c7ae73f can be picked an pushed )

For now i'd say it works as it should. Improvements can be made later on another PR if needed.

[rawbertp]

Done @andi34 .

I agree with both of you - the overlay doesn't look especially great but it is the same as it used to be before. So yes - it should be changed at some stage but I wouldn't consider this as an essential part of this PR either.