Own-Programming-Language-Tutorial/examples/canvas/fx_event_handlers.own

use canvasfx, std

w = 800   h = 600
g = window("JavaFX Event handler example", w, h)

addEventHandler(Events.MOUSE_MOVED, ::onMouseMoved)
addEventHandler(Events.MOUSE_DRAGGED, ::onMouseMoved)
addEventHandler(Events.KEY_PRESSED, def(e) {
  if (e.code == KeyCode.C) clearRect(0, 0, w, h)
})

def onMouseMoved(e) {
  g.setFill(Color.rgb(rand(255), rand(255), rand(255), rand()))
  m = 1 + e.isPrimaryButtonDown + e.isSecondaryButtonDown
  radius = m * rand(30, 50)
  g.fillOval(e.x - radius/2, e.y - radius/2, radius, radius)
}