Screenshot with CTRL + S

[ErraticGenerator]

source: Processing 1.0 - Processing Discourse - CONTROL + char commands.

boolean ctrlPressed = false;

void setup() {
  size(400, 400);
}

void draw() {
  background(200);
}

void keyPressed() {
  if (key == CODED) {
    if (keyCode == CONTROL) {
      println("control");
      ctrlPressed = true;
    }
  } else {
    if (ctrlPressed && keyCode == 83) { // 83 is keyCode for "s"
      println("ctrl + s");
      save("test.png");
    }
  }
}

void keyReleased() {
  if (key == CODED) {
    if (keyCode == CONTROL) {
      ctrlPressed = false;
    }
  }
}