Drawing interactions / published by https://github.com/dacr/code-examples-manager #8d3870b9-83fc-49f7-b535-0364796259b8/70361737d3a577178a1fd452c32e34ccf057c01a

vectorgraphics-doodle-example-interact.sc

// summary : Drawing interactions
// keywords : scala, vector-graphics, doodle, examples
// publish : gist
// authors : Noel Welsh, David Crosson
// license : Apache NON-AI License Version 2.0 (https://raw.githubusercontent.com/non-ai-licenses/non-ai-licenses/main/NON-AI-APACHE2)
// id : 8d3870b9-83fc-49f7-b535-0364796259b8
// created-on : 2019-08-12T16:28:07Z
// managed-by : https://github.com/dacr/code-examples-manager
// run-with : scala-cli $file

// ---------------------
//> using scala "3.5.1"
//> using dep "org.creativescala::doodle:0.26.0"
// ---------------------

//doodle.java2d.examples.Ripples.go
// https://github.com/creativescala/doodle/blob/master/java2d/src/main/scala/doodle/java2d/examples/Ripples.scala
// Copy paste of this example code with minor changes :

object Ripples {

  import cats.effect.IO
  import doodle.core.*
  import doodle.syntax.*
  import doodle.syntax.all.*
  import doodle.interact.*
  import doodle.interact.syntax.*
  import doodle.interact.syntax.all.*
  import doodle.java2d.*
  import doodle.java2d.effect.*
  import fs2.Stream
  import cats.effect.unsafe.implicits.global
  import scala.concurrent.duration.{FiniteDuration, MILLISECONDS}

  import cats.instances.all._
  import cats.syntax.all._

  val frame: Frame = Frame(
    size = Size.fixedSize(600, 600),
    title = "Photos",
    center = Center.atOrigin,
    background = Some(Color.midnightBlue),
    redraw = Redraw.clearToBackground
  )

  final case class Ripple(age: Int, x: Double, y: Double) {
    val maxAge = 400

    def alive: Boolean = age <= maxAge

    def older: Ripple =
      this.copy(age = age + 1)

    def picture =
      circle(age.toDouble)
        .strokeColor(
          Color.hotpink.alpha(((maxAge - age) / (maxAge.toDouble)).normalized)
        )
        .at(x, y)
  }

  def ripples(canvas: Canvas): IO[Stream[IO, Picture[Unit]]] = {
    import cats.effect.std.Queue
    Queue
      .bounded[IO, Option[Ripple]](5)
      .flatMap { queue =>
        val redraw = canvas.redraw
          .map(_ => none[Ripple])
          .evalMap(r => queue.offer(r))
          .compile
          .drain

        val mouseMove = canvas.mouseMove
          .debounce(
            FiniteDuration(100, MILLISECONDS)
          ) // Stop spamming with too many mouse events
          .map(pt => Ripple(0, pt.x, pt.y).some)
          .evalMap(r => queue.offer(r))
          .compile
          .drain

        val ripples: Stream[IO, Picture[Unit]] = Stream
          .fromQueueUnterminated(queue)
          .scan(List.empty[Ripple]) { (ripples, ripple) =>
            ripple match {
              case Some(r) => r :: ripples
              case None    => ripples.filter(_.alive).map(_.older)
            }
          }
          .map(ripples => ripples.map(_.picture).allOn)
        (redraw.start >> mouseMove.start).as(ripples)
      }
  }

  def go(): Unit = {
    frame
      .canvas()
      .use(canvas =>
        for {
          frames <- ripples(canvas)
          a      <- frames.animateWithCanvasToIO(canvas)
        } yield a
      )
      .unsafeRunAsync(x => println(x))
  }
}

Ripples.go()

scala.io.StdIn.readLine("Enter to exit...") // required when run as a script