Is there a way to Protect Alpha (or "lock pixels" as in PS) on a layer?

[jarombra 13]

This is a technique I use a lot of in Photoshop, where I either lock the pixels on a layer so whatever I paint only paints into those existing pixels, or I subordinate another layer from above in the hierarchy (the ALT + LClick trick) which achieves the same result. Is there any way to do something like this in the iPad Affinity Photo?

 

EDIT: I see on the macOS version what I am referring to is a check-box on the top dash called "Protect Alpha".

 

Thanks!

[Chris B 1,588]

Hey jarombra,

The iPad version has it on the Paint Brush Tool toolbar, at the end  

I assume you may have figured this out by now but hopefully the reply might be helpful to anyone else looking for an answer. 

[jarombra 13]

Awesome thanks!