Scala+swing
- 1. Scala Swing Ken Scambler
- 2. Origins of Swing Java’s main desktop programming environment
- 3. Single Threaded, MVC framework
- 4. Developed from Abstract Windowing Toolkit (AWT) in the late 90s
- 5. Sun has focused on the web rather than desktop
- 6. Has faded from the limelight
- 7. However still has many users and devotees
- 8. Swing’s Advantages Cross-platform (mostly!)
- 10. Flexible
- 11. Extensible
- 13. Comparable to native performance (nowadays!)
- 14. Swing’s Disadvantages Huge, complex API
- 15. Requires very verbose code
- 16. Events require anonymous inner class gymnastics!
- 17. Doesn’t integrate with Collection API
- 19. Introducing Scala Swing Thin wrapper framework
- 20. Far less code
- 22. Full integration with Scala Collections
- 23. Introducing Scala Swing Scala getter/setter properties
- 24. Events use pattern-matching and partial functions
- 25. Performance is just as good
- 26. Panels & Layouts Layouts are built into the panel
- 27. Eg. BorderPanel, GridPanel, FlowPanel
- 28. Add components with 'contents' buffer
- 29. FlowPanel new FlowPanel { contents += new Button( "A" ) contents += new Button( "B" ) contents += new Button( "C" ) contents += new Button( "D" ) }
- 30. GridPanel new GridPanel(3,3) { contents ++= 1 to 9 map ( n => new Button(n.toString)) }
- 31. BorderPanel new BorderPanel { import BorderPanel.Position._ layout( new Button( "West" )) = West layout( new Button( "Center" )) = Center layout( new Button( "North" )) = North }
- 32. Events No more XXXListeners!
- 33. Individual events are case classes
- 34. Event handlers are PartialFunctions which pattern match on events
- 35. Classes which emit events have the Publisher trait
- 36. Classes which listen to Publishers have the Reactor trait.
- 37. Publishers & Reactors trait Reactor { val reactions: Reactions def listenTo(ps: Publisher*): Unit def deafTo(ps: Publisher*): Unit } trait Publisher extends Reactor { def publish(e: Event): Unit listenTo( this ) }
- 38. ButtonClicked events new FlowPanel { // Panels are Reactors // Buttons are Publishers val button = new Button( "abc" ) listenTo(button) reactions += { case ButtonClicked(b) => println( "Clicked " + b.text) } //... }
- 39. ButtonClicked events // All publishers are reactors // that listen to themselves new Button( "abc" ) { reactions += { case ButtonClicked(b) => println( "Clicked " + b.text) } }
- 40. Mouse Events new FlowPanel { val pub = new FlowPanel listenTo( pub .mouse.clicks, pub .mouse.moves, pub .mouse.wheel) reactions += { case me: MouseClicked => case me: MouseDragged => case me: MouseEntered => case me: MouseExited => case me: MouseMoved => case me: MouseWheelMoved => } }
- 41. Selection Events new FlowPanel { val fruitList = List( "apples", "bananas", "pears" ) val listView = new ListView(fruitList ) listenTo( listView .selection) reactions += { case SelectionChanged(`fruitList`) => } }
- 42. ListViews class ListView[A] extends Component { def this (items: Seq[A]) = //... //... }
- 43. ListViews case class City(name: String, country: String, population: Int , capital: Boolean ) val items = List( City( "Lausanne" , "Schweiz" , 129273, false ), City( "Paris" , "France" , 2203817, true ), City( "New York" , "USA" , 8363710 , false ), City( "Berlin" , "Germany" , 3416300, true ), City( "Tokyo" , "Japan" , 12787981, true )) val view = new ListView(items) val cityNames = view.selection.items.map(_.name)
- 44. Renderers From the last example... val view = new ListView(items) { renderer = ListView.Renderer(_.name) } From the last example...
- 45. Custom Painting val panel = new Panel { background = Color.blue override protected def paintComponent(g: Graphics2D) { super .paintComponent(g) g setColor Color.red for (x <- 0 until size.width by 10) g.drawLine(x, 0, x, size.height) } }
- 46. Fun with mixins trait BlueBackground { this : Panel => background = Color.blue} trait BlackBackground { this : Panel => background = Color.black} trait VerticalLines extends Panel { override protected def paintComponent(g: Graphics2D) { super .paintComponent(g) g setColor Color.red for (x <- 0 until size.width by 10) g.drawLine(x, 0, x, size.height) } } trait HorizontalLines extends Panel { override protected def paintComponent(g: Graphics2D) { super .paintComponent(g) g setColor Color.white for (y <- 0 until size.height by 20) g.drawLine(0, y, size.width, y) } } trait Blobs extends Panel { override protected def paintComponent(g: Graphics2D) { super .paintComponent(g) g setColor Color.green for (x <- 0 until size.width by 20; y <- 0 until size.height by 40) g.fillOval(x-4, y-4, 8, 8) } }
- 47. Fun with mixins val panel = new Panel with BlueBackground with HorizontalLines with VerticalLines with Blobs
- 48. Fun with mixins val panel = new Panel with BlackBackground with Blobs with VerticalLines with HorizontalLines
- 49. A basic complete app object SwingTalk extends SimpleSwingApplication { def top = new MainFrame { contents = new GridPanel(1, 4) { val nameLabel = new Label( "Name" ) val nameText = new TextField val helloButton = new Button( "Say Hello" ) val goodbyeButton = new Button( "Say Goodbye" ) listenTo(helloButton, goodbyeButton) contents ++= nameLabel :: nameText :: helloButton :: goodbyeButton :: Nil reactions += { case ButtonClicked(`helloButton`) => Dialog.showMessage(nameLabel, "Hello, " + nameText.text) case ButtonClicked(`goodbyeButton`) => Dialog.showMessage(nameLabel, "Goodbye, " + nameText.text) } } } }
- 50. What's missing? Work in progress Drag N' Drop
- 51. Tree views
- 52. Better actor support for multi-threading EPFL are snowed under!
- 53. Community contributions will make a big difference
- 54. Questions