midi graphical visuals

Hello,

I'm working on a visualization project that I want to do with Max Msp, but I'm kind of stuck at some point.

I want to visualize midi notes on a screen. When a note is played, a graphical element (for the sake of simplification could be line) should display on this particular area (for as long as the note is pressed).

The component should also have 2 settings: fade in and fade out time, which define how long it takes for the element to fade in when the note is pressed, and how long it should take to fade out when the note is released.

My question is: how can a thing like this be accomplished when you want the ability that multiple notes can display multiple elements on the screen with different fade timings (based on their note lengths) ?

Thanks for any tips!