[SOLVED] How Processing knows that user is pressing multiple key at the same time?

How Processing knows that user is pressing multiple key at the same time?

I have no idea how Processing knows that a user is pressing Ctrl and some character at the same time.

Multiple buttons at same time only. Is it possible?

ex: (Ctrl+r).

Solution

You have to first check if Ctrl has been pressed. If it has been pressed then you save a boolean as true. The next time you press a button you check if the button is the button you want (i.e. 'r') and if the boolean is true. If both are true then Processing knows...

Here's a demonstration:

boolean isCtrlPressed = false;
boolean isRPressed = false;
void draw() {
  background(0);
  fill(255);
  if (isCtrlPressed) background(255, 0, 0);
  if (isRPressed) background(0, 255, 0);
  if (isCtrlPressed && isRPressed) background(255, 255, 0);
}
void keyPressed() {
  if (keyCode == CONTROL && isCtrlPressed == false) isCtrlPressed = true;
  if (char(keyCode) == 'R') isRPressed = true;

}
void keyReleased() {
  if (keyCode == CONTROL) isCtrlPressed = false;
  if (char(keyCode) == 'R') isRPressed = false;
}