//
// very simple program illustrating use of graphics class
// displays very simple proof-of-concept image
// prints information about (some) mouse events
// prints information about (some) keyboard events
// changes color in display if user types 'b' or 'g'
// (apparently user must click once in main window to get keyboard focus first)
//
import scala.swing._
import scala.swing.event._
import java.awt.Color
import java.awt.Graphics2D

// panel for drawing
val drawingPanel = new Panel {

  var color = Color.green

  // method used to "paint" panel on screen
  override def paint(g:Graphics2D) {
    println("paint called")
    g.setPaint(color)
    // g.fill(new Rectangle(10,20,100,200))
    // get width and height
    val w = size.width
    val h = size.height
    // rectangle half the size of the whole area, centered
    g.fill(new Rectangle(w/4, h/4, w/2, h/2))
  }

  // set up to receive mouse and keyboard input
  requestFocus() // request keyboard focus
  listenTo(mouse.clicks,mouse.moves,keys)

  // code to be called when mouse/keyboard input received --
  // mostly just prints things, but does change something in
  // display if user presses 'b' (short for "blue") or 'g' ("green")
  reactions += {

    case e:MousePressed => {
      println("mouse pressed "+e)
      requestFocus()
    }
    case e:MouseDragged => {
      println("mouse dragged "+e)
      requestFocus()
    }

    case e:KeyPressed => {
      println("key pressed "+e+" "+e.key)
      if (e.key == Key.Up) { println("up arrow") }
    }
    case e:KeyTyped => {
      println("key typed "+e.char)
      e.char match {
        case 'b' => {
            color = Color.blue
            repaint()
        }
        case 'g' => {
            color = Color.green
            repaint()
        }
        case _ => { }
      }
    }
  }
}

// main frame/window 
val frame = new MainFrame {
    title = "Hello!"
    contents = drawingPanel
    size = new Dimension(400,400)
}
frame.visible = true