Project: Scribble

Complete Solution

import scala.swing.*
import scala.swing.event.*
import java.awt.{Color, Graphics2D, Point, Rectangle, Shape}
import scala.collection.mutable.ListBuffer
import scala.swing.BorderPanel.Position.{Center, North}

object ScribbleApp extends SimpleSwingApplication:
  def top = new MainFrame:
    title = "Rectangle and Oval Scribble App"

    // Modes for drawing shapes
    sealed trait DrawMode
    case object Rectangle extends DrawMode
    case object Oval extends DrawMode

    var currentMode: DrawMode = Rectangle // Default mode

    // Canvas is a Panel where shapes are drawn
    object canvas extends Panel:
      background = Color.white
      preferredSize = new Dimension(400, 400)
      focusable = true
      listenTo(mouse.clicks, mouse.moves)

      private var startPoint: Option[Point] = None
      private val shapes: ListBuffer[Shape] = ListBuffer()

      // React to mouse events to draw shapes
      reactions += {
        case e: MousePressed =>
          startPoint = Some(e.point)

        case e: MouseReleased =>
          startPoint match
        case Some(start) =>
          val shape = currentMode match
        case Rectangle => new Rectangle(start.x, start.y, e.point.x - start.x, e.point.y - start.y)
        case Oval => new java.awt.geom.Ellipse2D.Double(start.x, start.y, e.point.x - start.x, e.point.y - start.y)
          shapes += shape
          repaint()
        case None =>
          startPoint = None
      }

      override def paintComponent(g: Graphics2D): Unit =
        super.paintComponent(g)
        g.setColor(Color.black)
        shapes.foreach:
          case rect: Rectangle => g.draw(rect)
          case oval: java.awt.geom.Ellipse2D.Double => g.draw(oval)
          case _ =>

    // Mode selection buttons
    val modePanel = new FlowPanel:
      val rectangleButton = new Button("Rectangle")
      val ovalButton = new Button("Oval")

      contents += rectangleButton
      contents += ovalButton

      listenTo(rectangleButton, ovalButton)

      reactions +=
        case ButtonClicked(`rectangleButton`) => currentMode = Rectangle
        case ButtonClicked(`ovalButton`) => currentMode = Oval

    contents = new BorderPanel:
      layout(modePanel) = North
      layout(canvas) = Center
    size = new Dimension(500, 500)