From be46f1de8031c38def2017930f3a719ece0725e0 Mon Sep 17 00:00:00 2001
From: Martin Ring <martin.ring@encoway.de>
Date: Mon, 13 Jun 2022 07:10:52 +0200
Subject: [PATCH] add paint example
---
lecture-08/build.sbt | 23 ++++
lecture-08/index.html | 11 ++
lecture-08/js/Main.scala | 189 ++++++++++++++++++++++++++++
lecture-08/jvm/Streams.scala | 32 +++++
lecture-08/project/build.properties | 1 +
lecture-08/project/plugins.sbt | 2 +
lecture-08/shared/Geometry.scala | 56 +++++++++
lecture-08/shared/Paint.scala | 30 +++++
8 files changed, 344 insertions(+)
create mode 100644 lecture-08/build.sbt
create mode 100644 lecture-08/index.html
create mode 100644 lecture-08/js/Main.scala
create mode 100644 lecture-08/jvm/Streams.scala
create mode 100644 lecture-08/project/build.properties
create mode 100644 lecture-08/project/plugins.sbt
create mode 100644 lecture-08/shared/Geometry.scala
create mode 100644 lecture-08/shared/Paint.scala
diff --git a/lecture-08/build.sbt b/lecture-08/build.sbt
new file mode 100644
index 0000000..b595364
--- /dev/null
+++ b/lecture-08/build.sbt
@@ -0,0 +1,23 @@
+ThisBuild / scalaVersion := "3.1.2"
+
+lazy val root = project.in(file("."))
+ .aggregate(lecture08.js, lecture08.jvm)
+ .settings(
+ publish := {},
+ publishLocal := {}
+ )
+
+lazy val lecture08 = crossProject(JSPlatform,JVMPlatform).in(file("."))
+ .settings(
+ Compile / scalaSource := baseDirectory.value,
+ name := "lecture-08",
+ )
+ .jvmSettings(
+ libraryDependencies += ("com.typesafe.akka" %% "akka-stream" % "2.6.14").cross(CrossVersion.for3Use2_13)
+ //libraryDependencies += "org.scala-js" %% "scalajs-dom" % "2.2.0"
+ )
+ .jsSettings(
+ libraryDependencies += ("org.akka-js" %%% "akkajsactorstream" % "2.2.6.14").cross(CrossVersion.for3Use2_13),
+ libraryDependencies += "org.scala-js" %%% "scalajs-dom" % "2.2.0",
+ scalaJSUseMainModuleInitializer := true
+ )
\ No newline at end of file
diff --git a/lecture-08/index.html b/lecture-08/index.html
new file mode 100644
index 0000000..8182bea
--- /dev/null
+++ b/lecture-08/index.html
@@ -0,0 +1,11 @@
+<!DOCTYPE html>
+<html lang="en">
+<head>
+ <meta charset="UTF-8">
+ <meta name="viewport" content="width=devide-width, initial-scale=1.0">
+ <title>Reactive Paint</title>
+</head>
+<body>
+ <script src="target/scala-3.1.2/lecture-08-fastopt.js"></script>
+</body>
+</html>
\ No newline at end of file
diff --git a/lecture-08/js/Main.scala b/lecture-08/js/Main.scala
new file mode 100644
index 0000000..180fb8b
--- /dev/null
+++ b/lecture-08/js/Main.scala
@@ -0,0 +1,189 @@
+import akka.NotUsed
+
+import akka.actor._
+import akka.stream._
+import akka.stream.scaladsl._
+import org.scalajs.dom._
+import org.scalajs.dom.ext.KeyCode
+import org.scalajs.dom.EventListenerOptions
+
+import scala.concurrent.ExecutionContext.Implicits.global
+import scala.concurrent.{Future, Promise}
+
+implicit class EventSource(val target: org.scalajs.dom.EventTarget):
+ def on[E <: Event](event: String): Source[E, NotUsed] =
+ Source.queue[E](2048, OverflowStrategy.fail).mapMaterializedValue { queue =>
+ val handler: scalajs.js.Function1[E, Unit] = (e: E) => queue.offer(e)
+ target.addEventListener(event, handler)
+ handler
+ }.watchTermination() {
+ case (h, d) =>
+ d.onComplete(_ => target.removeEventListener(event, h))
+ NotUsed
+ }
+
+@main def main(): Unit =
+ import PaintCommand._
+ given system: ActorSystem = ActorSystem("paint")
+ given Materializer = Materializer(system)
+
+ val canvas = document.createElement("canvas").asInstanceOf[html.Canvas]
+ document.body.appendChild(canvas)
+ canvas.style.position = "fixed"
+ canvas.style.left = "0"
+ canvas.style.right = "0"
+ canvas.style.top = "0"
+ canvas.style.bottom = "0"
+
+ canvas.width = window.innerWidth.toInt
+ canvas.height = window.innerHeight.toInt
+
+ val mouseDown =
+ canvas.on[MouseEvent]("mousedown")
+ .map(e => BeginDrag(e.clientX, e.clientY))
+
+ val mouseUp =
+ canvas.on[MouseEvent]("mouseup")
+ .map(e => EndDrag(e.clientX, e.clientY))
+
+ val mouseLeave =
+ canvas.on[MouseEvent]("mouseleave")
+ .map(e => EndDrag(e.clientX, e.clientY))
+
+ val mouseMove =
+ canvas.on[MouseEvent]("mousemove")
+ .map(e => Drag(e.clientX, e.clientY))
+
+ val mouseCommands = mouseDown.flatMapConcat { b =>
+ Source.single(b).concat(
+ mouseMove.merge(mouseUp merge mouseLeave).takeWhile(_.isInstanceOf[Drag], inclusive = true)
+ )
+ }
+
+ val keyboardCommands =
+ window.on[KeyboardEvent]("keydown")
+ .map(e => e.keyCode)
+ .collect {
+ case KeyCode.B => ChooseColor("blue")
+ case KeyCode.G => ChooseColor("green")
+ case KeyCode.R => ChooseColor("red")
+ case KeyCode.Up => IncStrokeWidth
+ case KeyCode.Down => DecStrokeWidth
+ case KeyCode.Left => SelectPrev
+ case KeyCode.Right => SelectNext
+ case KeyCode.Backspace => Cut
+ case KeyCode.Enter => Paste
+ case KeyCode.C => Copy
+ }
+
+ val commands: Source[PaintCommand, NotUsed] =
+ mouseCommands merge keyboardCommands
+
+ val paint: Flow[PaintCommand, PaintState, NotUsed] =
+ Flow[PaintCommand].scan(PaintState.initial) {
+ case (state, ChooseColor(c)) =>
+ if (state.isSelected) state.modifySelected(_.copy(color = c))
+ else state.copy(color = c)
+ case (state, IncStrokeWidth) =>
+ if (state.isSelected) state.modifySelected(p => p.copy(width = p.width + 1))
+ else state.copy(width = state.width + 1)
+ case (state, DecStrokeWidth) =>
+ if (state.isSelected) state.modifySelected(p => p.copy(width = Math.max(1,p.width - 1)))
+ else state.copy(width = Math.max(1,state.width - 1))
+ case (state, BeginDrag(x, y)) =>
+ val s = state.paths.indexWhere(_.hits(x,y))
+ if (s > -1) state.copy(
+ selected = s,
+ dragStart = (x,y)
+ ) else state.copy(
+ selected = -1,
+ currentPath = Some(Path(state.color, state.width, Vector(Point(x, y)))))
+ case (state, Drag(x, y)) =>
+ if (state.isSelected) state.modifySelected(p => p.copy(points = p.points.map {
+ case Point(px,py) => Point(px + x - state.dragStart._1,py + y - state.dragStart._2)
+ })).copy(dragStart = (x,y)) else state.copy(
+ currentPath = state.currentPath.map(_.append(x, y)))
+ case (state, EndDrag(x, y)) =>
+ if (state.isSelected) state.modifySelected(p => p.copy(points = p.points.map {
+ case Point(px,py) => Point(px + x - state.dragStart._1,py + y - state.dragStart._2)
+ })) else state.copy(
+ paths = state.currentPath.filter(!_.isEmpty).map(_.append(x,y)).toList ++ state.paths,
+ currentPath = None)
+ case (state, SelectPrev) =>
+ if (state.selected > 0 && state.selected < state.paths.length) {
+ state.copy(selected = state.selected - 1)
+ } else state.copy(selected = state.paths.length - 1)
+ case (state, SelectNext) =>
+ if (state.selected > -1 && state.selected < state.paths.length - 1) {
+ state.copy(selected = state.selected + 1)
+ } else state.copy(selected = 0)
+ case (state, Copy) =>
+ if (state.isSelected) state.copy(
+ clipboard = Some(state.paths(state.selected)))
+ else state
+ case (state, Cut) =>
+ if (state.isSelected) {
+ val (before,deleted :: after) = state.paths.splitAt(state.selected)
+ state.copy(
+ paths = before ++ after,
+ clipboard = Some(deleted),
+ selected = -1
+ )
+ } else state
+ case (state, Paste) =>
+ if (state.clipboard.isDefined) state.copy(
+ paths = state.clipboard.toList ++ state.paths,
+ selected = 0
+ ) else state
+ }
+
+ def visualize = Sink.foreach[PaintState] {
+ case s@PaintState(color, width, paths, _, currentPath, selected, _) =>
+ val context = canvas.getContext("2d").asInstanceOf[raw.CanvasRenderingContext2D]
+ context.lineJoin = "round"
+ context.lineCap = "round"
+ context.clearRect(0,0,canvas.width,canvas.height)
+ paths.zipWithIndex.reverse.foreach {
+ case (p@Path(color, width, points),i) =>
+ if (i == selected) {
+ context.shadowColor = "blue"
+ context.shadowBlur = width
+ }
+ context.strokeStyle = color
+ context.lineWidth = width
+ context.beginPath()
+ p.controlPoints.headOption.foreach {
+ case Point(x, y) => context.moveTo(x, y)
+ }
+ p.controlPoints.drop(1).grouped(3).foreach {
+ case Seq(c1,c2,p) => context.bezierCurveTo(c1.x,c1.y,c2.x,c2.y,p.x,p.y)
+ }
+ context.stroke()
+ context.shadowColor = null
+ context.shadowBlur = 0
+ }
+ currentPath.foreach {
+ case Path(color, width, points) =>
+ context.strokeStyle = color
+ context.lineWidth = width
+ context.beginPath()
+ points.headOption.foreach {
+ case Point(x, y) => context.moveTo(x, y)
+ }
+ points.drop(1).foreach {
+ case Point(x, y) => context.lineTo(x, y)
+ }
+ context.stroke()
+ }
+ context.shadowColor = null
+ context.shadowBlur = 0
+ // visualize state
+ context.strokeStyle = color
+ context.lineWidth = width
+ context.beginPath()
+ context.moveTo(10 + width / 2,10 + width)
+ context.lineTo(10 + width / 2,50)
+ context.stroke()
+ }
+
+ (commands via paint to visualize).run()
\ No newline at end of file
diff --git a/lecture-08/jvm/Streams.scala b/lecture-08/jvm/Streams.scala
new file mode 100644
index 0000000..b619458
--- /dev/null
+++ b/lecture-08/jvm/Streams.scala
@@ -0,0 +1,32 @@
+import akka.actor.ActorSystem
+import akka.stream.Materializer
+import akka.stream.scaladsl._
+import scala.concurrent.Future
+import scala.concurrent.ExecutionContext
+import akka.NotUsed
+import scala.concurrent.duration._
+import akka.stream.OverflowStrategy
+
+given system: ActorSystem = ActorSystem("paint")
+given ExecutionContext = system.dispatcher
+given Materializer = Materializer(system)
+
+def sum =
+ val source1 = Source.tick(1.second,1.second,0)
+ val source2 = Source(Stream.iterate(0)(_ + 1))
+ val source = source1.zip(source2)
+ val sink = Sink.foreach[Any](i => println("step: " + i))
+ val sum = source runWith sink
+ sum
+
+def error1 =
+ val source = Source(0 to 5).map(100 / _)
+ val result = source.runWith(Sink.fold(0)(_ + _))
+ result
+
+def error2 =
+ val source = Source(0 to 5).map(100 / _).recover {
+ case _: ArithmeticException => 0
+ }
+ val result = source.runWith(Sink.fold(0)(_ + _))
+ result
\ No newline at end of file
diff --git a/lecture-08/project/build.properties b/lecture-08/project/build.properties
new file mode 100644
index 0000000..c8fcab5
--- /dev/null
+++ b/lecture-08/project/build.properties
@@ -0,0 +1 @@
+sbt.version=1.6.2
diff --git a/lecture-08/project/plugins.sbt b/lecture-08/project/plugins.sbt
new file mode 100644
index 0000000..82dde6b
--- /dev/null
+++ b/lecture-08/project/plugins.sbt
@@ -0,0 +1,2 @@
+addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.10.0")
+addSbtPlugin("org.portable-scala" % "sbt-scalajs-crossproject" % "1.0.0")
\ No newline at end of file
diff --git a/lecture-08/shared/Geometry.scala b/lecture-08/shared/Geometry.scala
new file mode 100644
index 0000000..0060cce
--- /dev/null
+++ b/lecture-08/shared/Geometry.scala
@@ -0,0 +1,56 @@
+case class Point(
+ x: Double,
+ y: Double
+):
+ def +(that: Point) = Point(this.x + that.x, this.y + that.y)
+ def unary_- : Point = Point(-x,-y)
+ def -(that: Point) = this + (- that)
+ def *(scalar: Double) = Point(x*scalar,y*scalar)
+ def magnitude: Double = Math.sqrt(Math.pow(x,2) + Math.pow(y,2))
+ def phi: Double = Math.atan2(y,x)
+ def normalized: Point = Point(Math.cos(phi),Math.sin(phi))
+
+object Point:
+ def distance(a: Point, b: Point): Double = (a - b).magnitude
+
+case class Path(
+ color: String,
+ width: Int,
+ points: Vector[Point]
+):
+ def append(x: Double, y: Double): Path = {
+ if (points.length > 1 && Point.distance(points.last,points.init.last) <= width * 2)
+ copy(points = points.init :+ Point(x,y))
+ else
+ copy(points = points :+ Point(x,y))
+ }
+
+ val scale = 0.5
+
+ lazy val controlPoints: Seq[Point] = (for (i <- 0 until points.length) yield {
+ if (i == 0) {
+ val p1 = points(i)
+ val p2 = points(i+1)
+ val tangent = p2 - p1;
+ val q1 = p1 + tangent * scale;
+ Seq(p1,q1)
+ } else if (i == points.length - 1) {
+ val p0 = points(i - 1)
+ val p1 = points(i)
+ val tangent = (p1 - p0);
+ val q0 = p1 - tangent * scale;
+ Seq(q0,p1)
+ } else {
+ val p0 = points(i - 1)
+ val p1 = points(i)
+ val p2 = points(i + 1)
+ val tangent = (p2 - p0).normalized;
+ val q0 = p1 - tangent * scale * (p1 - p0).magnitude;
+ val q1 = p1 + tangent * scale * (p2 - p1).magnitude;
+ Seq(q0,p1,q1)
+ }
+ }).flatten
+
+ def hits(x: Double, y: Double): Boolean = points.exists(p => Point.distance(p,Point(x,y)) <= width)
+
+ def isEmpty: Boolean = points.length < 2
diff --git a/lecture-08/shared/Paint.scala b/lecture-08/shared/Paint.scala
new file mode 100644
index 0000000..b67bf62
--- /dev/null
+++ b/lecture-08/shared/Paint.scala
@@ -0,0 +1,30 @@
+case class PaintState(
+ color: String,
+ width: Int,
+ paths: List[Path],
+ clipboard: Option[Path],
+ currentPath: Option[Path],
+ selected: Int,
+ dragStart: (Double,Double)
+):
+ def isSelected: Boolean = selected > -1 && selected < paths.length
+ def modifySelected(f: Path => Path): PaintState = {
+ val (before,s :: after) = paths.splitAt(selected)
+ copy(paths = before ++ (f(s) :: after))
+ }
+
+object PaintState:
+ def initial = PaintState("black",5,List.empty,Option.empty,None,-1,(0,0))
+
+enum PaintCommand:
+ case ChooseColor(color: String)
+ case IncStrokeWidth
+ case DecStrokeWidth
+ case BeginDrag(x: Double, y: Double)
+ case Drag(x: Double, y: Double)
+ case EndDrag(x: Double, y: Double)
+ case Cut
+ case Copy
+ case Paste
+ case SelectNext
+ case SelectPrev
\ No newline at end of file
--
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