Bezier Demo: Enable Touch, Mouse Drag and Slider

BezierDrawer.java

package net.javainthebox.bezier;

import javafx.application.Application;
import javafx.beans.binding.Bindings;
import javafx.beans.property.DoubleProperty;
import javafx.scene.Group;
import javafx.scene.Node;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.control.Slider;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.shape.CubicCurve;
import javafx.scene.shape.Line;
import javafx.scene.shape.StrokeLineCap;
import javafx.stage.Stage;

public class BezierDrawer extends Application {
    private static final double INIT_SIZE = 600.0;
    private static final double BOTTOM_PANE_HEIGHT = 320.0;

    private final Circle start = new Circle(20, 250, 15);
    private final Circle end = new Circle(580, 250, 15);
    private final Circle control1 = new Circle(100, 250, 15);
    private final Circle control2 = new Circle(500, 250, 15);
    private final Line line1 = new Line();
    private final Line line2 = new Line();

    private final Slider startXSlider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider startYSlider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider controlX1Slider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider controlY1Slider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider controlX2Slider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider controlY2Slider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider endXSlider = new Slider(0, INIT_SIZE, 0.0);
    private final Slider endYSlider = new Slider(0, INIT_SIZE, 0.0);

    private final CubicCurve bezier = new CubicCurve();
    private Scene scene;
    
    @Override
    public void start(Stage stage) {
        Group root = new Group();
        scene = new Scene(root, INIT_SIZE, INIT_SIZE + BOTTOM_PANE_HEIGHT);

        Group mainPane = new Group();
        root.getChildren().add(mainPane);
        initBezier(mainPane);

        AnchorPane bottom = new AnchorPane();
        bottom.setPrefSize(INIT_SIZE, BOTTOM_PANE_HEIGHT);
        bottom.translateYProperty().bind(Bindings.subtract(scene.heightProperty(), BOTTOM_PANE_HEIGHT));
        root.getChildren().add(bottom);
        initBottomPane(bottom);

        stage.setTitle("Bezier Drawer");
        stage.setScene(scene);
        stage.show();
    }

    private void initBezier(Group mainPane) {
        start.setFill(Color.RED);
        start.setStroke(null);
        configurateDrag(start);

        end.setFill(Color.RED);
        end.setStroke(null);
        configurateDrag(end);

        control1.setFill(Color.CYAN);
        control1.setStroke(null);
        configurateDrag(control1);

        control2.setFill(Color.CYAN);
        control2.setStroke(null);
        configurateDrag(control2);

        line1.setFill(null);
        line1.setStroke(Color.GRAY);
        line1.setStrokeWidth(3);
        line1.setStrokeLineCap(StrokeLineCap.BUTT);
        line1.getStrokeDashArray().add(8.0);

        line1.startXProperty().bind(start.centerXProperty());
        line1.startYProperty().bind(start.centerYProperty());
        line1.endXProperty().bind(control1.centerXProperty());
        line1.endYProperty().bind(control1.centerYProperty());

        line2.setFill(null);
        line2.setStroke(Color.GRAY);
        line2.setStrokeWidth(3);
        line2.setStrokeLineCap(StrokeLineCap.BUTT);
        line2.getStrokeDashArray().add(8.0);

        line2.startXProperty().bind(control2.centerXProperty());
        line2.startYProperty().bind(control2.centerYProperty());
        line2.endXProperty().bind(end.centerXProperty());
        line2.endYProperty().bind(end.centerYProperty());

        bezier.setStroke(Color.DARKBLUE);
        bezier.setStrokeWidth(6);
        bezier.setFill(null);

        bezier.startXProperty().bind(start.centerXProperty());
        bezier.startYProperty().bind(start.centerYProperty());
        bezier.controlX1Property().bind(control1.centerXProperty());
        bezier.controlY1Property().bind(control1.centerYProperty());
        bezier.controlX2Property().bind(control2.centerXProperty());
        bezier.controlY2Property().bind(control2.centerYProperty());
        bezier.endXProperty().bind(end.centerXProperty());
        bezier.endYProperty().bind(end.centerYProperty());

        mainPane.getChildren().addAll(bezier, line1, line2, start, end, control1, control2);
    }

    private void configurateDrag(Circle circle) {
        circle.setOnMouseDragged(event -> {
            circle.setCenterX(event.getSceneX());
            circle.setCenterY(event.getSceneY());
        });

        circle.setOnTouchMoved(event -> {
            circle.setCenterX(event.getTouchPoint().getSceneX());
            circle.setCenterY(event.getTouchPoint().getSceneY());
        });
    }

    private void initBottomPane(AnchorPane pane) {
        Label startX = new Label("Start X:");
        configureAnchor(startX, 20.0, 0.0, 500.0);
        Label startY = new Label("Start Y:");
        configureAnchor(startY, 20.0, 40.0, 500.0);

        Label controlX1 = new Label("Control1 X:");
        configureAnchor(controlX1, 20.0, 80.0, 500.0);
        Label controlY1 = new Label("Control1 Y:");
        configureAnchor(controlY1, 20.0, 120.0, 500.0);

        Label controlX2 = new Label("Control2 X:");
        configureAnchor(controlX2, 20.0, 160.0, 500.0);
        Label controlY2 = new Label("Control2 Y:");
        configureAnchor(controlY2, 20.0, 200.0, 500.0);

        Label endX = new Label("End X:");
        configureAnchor(endX, 20.0, 240.0, 500.0);
        Label endY = new Label("End Y:");
        configureAnchor(endY, 20.0, 280.0, 500.0);

        configureSlider(startXSlider, start.centerXProperty());
        configureAnchor(startXSlider, 100.0, 0.0, 20.0);
        configureSlider(startYSlider, start.centerYProperty());
        configureAnchor(startYSlider, 100.0, 40.0, 20.0);

        configureSlider(controlX1Slider, control1.centerXProperty());
        configureAnchor(controlX1Slider, 100.0, 80.0, 20.0);
        configureSlider(controlY1Slider, control1.centerYProperty());
        configureAnchor(controlY1Slider, 100.0, 120.0, 20.0);

        configureSlider(controlX2Slider, control2.centerXProperty());
        configureAnchor(controlX2Slider, 100.0, 160.0, 20.0);
        configureSlider(controlY2Slider, control2.centerYProperty());
        configureAnchor(controlY2Slider, 100.0, 200.0, 20.0);

        configureSlider(endXSlider, end.centerXProperty());
        configureAnchor(endXSlider, 100.0, 240.0, 20.0);
        configureSlider(endYSlider, end.centerYProperty());
        configureAnchor(endYSlider, 100.0, 280.0, 20.0);

        pane.getChildren().addAll(
                startX, startY,
                controlX1, controlY1,
                controlX2, controlY2,
                endX, endY,
                startXSlider, startYSlider,
                controlX1Slider, controlY1Slider,
                controlX2Slider, controlY2Slider,
                endXSlider, endYSlider);
    }
    
    private void configureAnchor(Node node, double left, double top, double right) {
        AnchorPane.setLeftAnchor(node, left);
        AnchorPane.setTopAnchor(node, top);
        AnchorPane.setRightAnchor(node, right);
    }

    private void configureSlider(Slider slider, DoubleProperty target) {
        slider.valueProperty().bindBidirectional(target);
        slider.maxProperty().bind(
                Bindings.max(scene.widthProperty(), 
                             Bindings.subtract(scene.heightProperty(), BOTTOM_PANE_HEIGHT)));
        slider.setShowTickMarks(true);
        slider.setShowTickLabels(true);
        slider.setMajorTickUnit(100.0);
    }
    
    public static void main(String... args) {
        launch(args);
    }
}