For me its the ‘Knock Code’ that LG had on their phones (I really wish LG still made at least the V series phones)
Basically there was a four-square area and you set up a sequence of where you would tap to unlock the phone. That set of squares was only shown when you set up the code
Then, to unlock your phone, you would tap those areas in the sequence you set up (even with the screen off).
Fingerprint readers are nice, but I really do miss the knock code
Edit: did find this article with a way to do the knock code, but if done wrong, could brick your phone I guess.
Plus, article is from 2014. When I looked at XDA’s info on it (they also being the developers) it looks like development on it is over, but individual modules may or may not still be supported by their devs
What? You’re still tapping the screen.
I didn’t word that correctly, you’re right In being able to see someone tapping their screen.
I don’t know how familiar you are with the knock code. These are the reasons why it’s near impossible for people around you to figure out the pattern, while still being very convenient:
You can have a very long knockcode, but still enter it really fast once commited to muscle memory
You can enter it while the phone is in Standby with display of
And lastly, the 4 seems weren’t absolute in size and location on display. You could pick up your phone and enter the knockcode with your thumb, only moving it in minimal distances relative to each segments, and the knockcode would be registered. These possible small movements compared with a relatively long code make it nigh impossible to figure out from observation