JavaFXでUNDECORATEDなWindowをドラッグで移動する

javafx_movable-undeco-window.groovy

/*
JavaFXでUNDECORATEDなウィンドウをドラッグで移動する
実行: groovy javafx_movable-undeco-window.groovy
*/

import javafx.application.Application
import javafx.scene.Scene
import javafx.scene.control.Label
import javafx.scene.layout.Background
import javafx.scene.layout.BackgroundFill
import javafx.scene.layout.BorderPane
import javafx.scene.layout.Pane
import javafx.scene.paint.Color
import javafx.stage.Stage
import javafx.stage.StageStyle

Application.launch(App, args)
class App extends Application {
    @Override 
    void start(Stage stage) {
        def sc = new Scene(pane(stage), 300, 250)
        stage.initStyle(StageStyle.UNDECORATED)
        stage.scene = sc
        stage.show()
    }
    def pane(window) {
        def topPane = new Pane(new Label("Drag here!"))
        topPane.background =
            new Background(new BackgroundFill(Color.color(0.5, 0.5, 0.5), null, null))
        double pickedX, pickedY
        topPane.onMousePressed = {
            pickedX = it.sceneX
            pickedY = it.sceneY
        }
        topPane.onMouseDragged = {
            window.x = it.screenX - pickedX
            window.y = it.screenY - pickedY
        }
        def pane = new BorderPane()
        pane.top = topPane
        pane
    }
}