Enable taking photo with "volume down" button

[zepod]

Obvious stuff
In almost every app that takes photos, it is possible to take photo via pressing the volume down button. It's a minor UX feature, but industry standard.

While on Camera screen, pressing the button should take photo.

Experiment
Let's try to experiment a bit, if it doesn't work UX-wise we will change it later.
Shooting via "volume down" button, does not automatically open the "preview" screen. Instead it behaves like you're taking another page.

[EskelCz]

I would say this should be implemented into the react-native-camera library itself.
There is an issue for it already, just no code yet.
react-native-camera/react-native-camera#764
I'll look into it.

[EskelCz]

Another option would be to create a new library just for this purpose.
I've found a lot of code for both platforms separately, it's just a matter of combining them into a new one which covers both with the same api.

https://github.com/FakeYou/react-native-volume
https://github.com/ifours/react-native-volume-slider
https://github.com/gevorg94/react-native-volume-handler
https://github.com/thebylito/react-native-button-handler
https://github.com/rnavarych/react-native-volume-button-handler

I've already done something similar, it shouldn't be too hard.

[zepod]

I like doing PR to react-native-camera, but we don't use RNC. We could do PR to expo, however. Doing new lib for it, seems like an overkill. What do you think?

[EskelCz]

Sorry I meant expo. Actually I think it's the other way around. Creating a library is fairly easy and you cant test what is necessary in a standalone situation, then it can more easily be merged into an existing library.
Still, it would take me about a day for each platform.