Drawing commands on a game?

In a game, I wanted to implement a system where during at any stage of the game (except menus of course), if the player "draws" a shape, it will recognise the shape and run the command accordingly. (I would love it if this was possible on a mobile device, but if not PC based games are alright too). Basically a certain drawn shape would act the same way as if a certain button was pressed.

For example, if during the game a player were to draw a circle, it will recognise it and run a unique command. But if I drew a triangle, or moved up and down the screen really quickly, it would different commands depending on the movement on the screen.

If drawing any free shape is impossible, i also have an idea (if it makes it easier to code) where it could have a screen like a smartphone pattern lock, and if certain patterns were drawn, it would do the same.

Which tools would I have to use, and how can i achieve this? Thank you so much!