KeyState respond to the state of a key

superclass: UGen

*kr(keycode, minval, maxval, lag)

keycode - The keycode value of the key to check. This corresponds to the keycode values passed into the keyDownActions of SCViews. See example below.

minval - The value to output when the key is not pressed.

maxval - The value to output  when the key is pressed.

lag - A lag factor.

See also MouseButton, MouseX, MouseY 

Note that this UGen does not prevent normal typing. It therefore may be helpful to select a GUI window rather than an SC document when using KeyState, as the latter will be altered by any keystrokes.

s.boot;

// execute the code below to find out a key's keycode

// the char and keycode of any key you press will be printed in the post window

(

w = SCWindow.new("I catch keystrokes");

w.view.keyDownAction = { arg view, char, modifiers, unicode, keycode;  [char, keycode].postln; };

w.front;

)

// then execute this and then press the 'j' key

(

w.front; // something safe to type on

{ SinOsc.ar(800, 0, KeyState.kr(38, 0, 0.1)) }.play;

)