DragonPlotter.scala

/*
 ドラゴンカーブを描くアプレット
 
 追々カオス理論のPlotterを作りたい。
 Type Bindingを使って抽象化したい。
 */
package takedasoft

import javax.swing.{JPanel,JFrame}
import java.awt.{Color,Graphics,Graphics2D,Dimension}
import java.awt.image.{BufferedImage}
import scala.concurrent.ops.spawn

class DragonPanel extends JPanel {
  
    val WIDTH:Int = 400
    val HEIGHT:Int = 400
    setPreferredSize(new Dimension( WIDTH , HEIGHT ))
    
    var image:BufferedImage = null //描画領域

    override def paint(g:Graphics) {
       if (image == null) startDraw()
       else g.drawImage(image, 0, 0, this) //imageからアプレットへのコピー
    }
    
    def startDraw(){
        image = new BufferedImage(WIDTH, HEIGHT, BufferedImage.TYPE_INT_ARGB)
        var graphics:Graphics2D = image.createGraphics
        graphics.translate(0, HEIGHT)
        graphics.scale(1, -1)
        graphics.setColor(Color.red)
        graphics.setBackground(getBackground())

        var plotter:Plotter = new Plotter(graphics)
        plotter.moveTo(100, 100)

        spawn {  draw(plotter, 10, 200, 0, 1)  }
    }
    
    def draw( pt:Plotter, n:int, dx:double, dy:double, sign:int ) {
        if (n == 0) {
            pt.drawRelative(dx, dy)
            repaint()
            Thread.sleep(10)
            return
        }else{
          draw(pt, n - 1, (dx - sign * dy) / 2, (dy + sign * dx) / 2,  1)
          draw(pt, n - 1, (dx + sign * dy) / 2, (dy - sign * dx) / 2, -1)
        }
    }
}

object DragonPlotter extends Application{
    var panel:DragonPanel = new DragonPanel();
    var frame:JFrame = new JFrame();
    frame.getContentPane.add(panel)
    frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    frame.pack()
    frame.setTitle("dragon curve plotter")
    frame.setResizable(false)
    frame.show
}

Plotter.scala

/*
 * Plotter.scala
 */
package takedasoft

import java.awt.{Graphics2D,BasicStroke}
import java.awt.geom.Line2D

class Plotter {
  
    var g:Graphics2D = null
    var x:double = 0
    var y:double = 0
    var line:Line2D.Double = new Line2D.Double()

    def this(g:Graphics2D){
      this()
      this.g = g
    }

    def setLineWidth(lineWidth:double):Unit={
        g.setStroke(new BasicStroke(lineWidth.toFloat));
    }

    def moveTo( x:double, y:double ) {
        this.x = x
        this.y = y
    }

    def moveRelative( dx:double, dy:double ) {
        moveTo(x + dx, y + dy);
    }

    def drawTo( x:double, y:double ) {
        line.setLine(this.x, this.y, x, y)
        g.draw(line)
        this.x = x
        this.y = y
    }

    def drawRelative( dx:double, dy:double ) {
        drawTo(x + dx, y + dy);
    }
}