canvas1.scala

//> using scala 3.3.0

/*
canvas1.scala

Initial image/canvas app with minimal features
Creates a simple PPM
https://en.wikipedia.org/wiki/Netpbm

scala-cli canvas1.scala

 */

case class Colour(r: Int, g: Int, b: Int)

case class Image[T](w: Int, h: Int, data: Vector[T]):
  def apply(x: Int, y: Int): T = data(x * h + y)
  def map[S](f: T => S): Image[S] = Image(w, h, data map f)
  def updated(x: Int, y: Int, value: T): Image[T] =
    Image(w, h, data.updated(x * h + y, value))

case object Image:
  def blank(w: Int, h: Int): Image[Colour] =
    Image(w, h, Vector.fill[Colour](w * h)(Colour(255, 255, 255)))
  def saveAsPPM(im: Image[Colour], fileName: String): Unit =
    val fs = new java.io.FileWriter(fileName)
    fs.write(s"P3 ${im.w} ${im.h} 255\n")
    (0 until im.h).foreach(y =>
      (0 until im.w).foreach(x =>
        val p = im(x, y)
        fs.write(s"${p.r} ${p.g} ${p.b}\n")
      )
    )
    fs.close()

object CanvasApp:

  val white = Colour(255, 255, 255)
  val black = Colour(0, 0, 0)
  val red = Colour(255, 0, 0)
  val green = Colour(0, 255, 0)
  val blue = Colour(0, 0, 255)

  @main def main() =
    println("Hello")
    val im = Image.blank(10, 8)
    val im1 = im.updated(3, 2, black).updated(4, 3, red)
    Image.saveAsPPM(im1, "test1.ppm")
    println("Goodbye")

// eof