Customizable Remote Input (Android>Windows)

Hello all,

I am looking for an application that will allow me to connect to my Windows computer (host programmed) on a keyboard-type interface. In here I would like the option to make customizable buttons which allow me to run shortcuts on multiple key-presses not bound to a single application.

There is an app which does this for Adobe Photoshop, which allows you to change your penstyle, thickness, transparency etc.. But this ONLY works for Photoshop, which I do no use. Many programs support linking a hotkey to a certain tool for example:

CTRL+P = Pen
CTRL+B = Brush
CTRL+[Arrow Up] = Brush size up
CTRL+[Arrow Right] = Transparency up

If there is an application where you can place your own buttons with a png as backdrop for the icons, it makes drawing with a drawing pad a lot easier because a lot of people, like me, cover their keyboard with the drawing pad having to move the drawing pad every time to use the keyboard to change some options.

Does anyone know of such an app or advice on how to make this?

Thank you!

Danco

P.S.
I made a quick dirty drawing of an example of my idea. Any thoughts are welcome!