将线绑定到可拖动的FlowPane（或任何矩形区域）

Question

我正在尝试创建UML编辑器。我发现了许多代码变体，这些变体从JavaFX Shape库中提取圆圈，并使其可拖动，并在其中心跟随一行。我以为可以从这些程序中获取逻辑并将其应用于任何类型的窗格（在我的迭代中，我选择了FlowPane）。但是，当我这样做时，生产线只会停留在原位，而不会跟随可拖动的窗格。

我尝试了几次迭代，使用了不同的Pane类型，并尝试使用了Rectangle，但是相同的问题不断发生。矩形图中线的端点不会随之拖动。

（注意：大部分代码来自www.java2s.com上可拖动的圆圈和线条的示例。我的代码由createBox和connectBox函数组成）

我的“创建可拖动矩形”功能：

private FlowPane createBox (double posX, double posY) {
      FlowPane node = new FlowPane();
      node.setPrefSize(100, 100);
      node.setStyle(
                "-fx-background-color: black; "
                + "-fx-text-fill: black; "
                + "-fx-border-color: black;");
      node.setLayoutX(posX);
      node.setLayoutY(posY);

      node.setCursor(Cursor.HAND);

      node.setOnMousePressed((t) -> {
          orgSceneX = t.getSceneX();
          orgSceneY = t.getSceneY();
      });
      node.setOnMouseDragged((t) -> {
          double offsetX = t.getSceneX() - orgSceneX;
          double offsetY = t.getSceneY() - orgSceneY;

          Pane c = (Pane) (t.getSource());

          c.setLayoutX(c.getLayoutX() + offsetX);
          c.setLayoutY(c.getLayoutY() + offsetY);

          orgSceneX = t.getSceneX();
          orgSceneY = t.getSceneY();
        });

      return node;
  }

提供的可拖动的圆和直线连接功能：

  private Circle createCircle(double x, double y, double r, Color color) {
    Circle circle = new Circle(x, y, r, color);

    circle.setCursor(Cursor.HAND);

    circle.setOnMousePressed((t) -> {
      orgSceneX = t.getSceneX();
      orgSceneY = t.getSceneY();

      Circle c = (Circle) (t.getSource());
      c.toFront();
    });
    circle.setOnMouseDragged((t) -> {
      double offsetX = t.getSceneX() - orgSceneX;
      double offsetY = t.getSceneY() - orgSceneY;

      Circle c = (Circle) (t.getSource());

      c.setCenterX(c.getCenterX() + offsetX);
      c.setCenterY(c.getCenterY() + offsetY);

      orgSceneX = t.getSceneX();
      orgSceneY = t.getSceneY();
    });
    return circle;
  }

  private Line connect(Circle c1, Circle c2) {
    Line line = new Line();

    line.startXProperty().bind(c1.centerXProperty());
    line.startYProperty().bind(c1.centerYProperty());

    line.endXProperty().bind(c2.centerXProperty());
    line.endYProperty().bind(c2.centerYProperty());

    line.setStrokeWidth(1);
    line.setStrokeLineCap(StrokeLineCap.BUTT);
    line.getStrokeDashArray().setAll(1.0, 4.0);

    return line;
  }

我的线连接功能（在我的“矩形”之间一个圆）：

private Line connectBox(FlowPane c1, Circle c2) {
        Line line = new Line();

        line.startXProperty().bind(c1.widthProperty().divide(2).add(c1.getLayoutX()));
        line.startYProperty().bind(c1.heightProperty().divide(2).add(c1.getLayoutY()));

        line.endXProperty().bind(c2.centerXProperty());
        line.endYProperty().bind(c2.centerYProperty());

        line.setStrokeWidth(1);
        line.setStrokeLineCap(StrokeLineCap.BUTT);
        line.getStrokeDashArray().setAll(1.0, 4.0);

        return line;
      }

程序的开始：

  @Override
  public void start(Stage primaryStage) {
    Group root = new Group();
    Scene scene = new Scene(root, 500, 260);


    // circles
    Circle redCircle = createCircle(100, 50, 30, Color.RED);
    Circle blueCircle = createCircle(20, 150, 20, Color.BLUE);
    Circle greenCircle = createCircle(40, 100, 40, Color.GREEN);

    FlowPane box1 = createBox(100, 130);


    Line line1 = connect(redCircle, blueCircle);
    Line line2 = connect(redCircle, greenCircle);
    Line line3 = connect(greenCircle, blueCircle);
    Line line4 = connectBox(box1, blueCircle);

    // add the circles
    root.getChildren().add(redCircle);
    root.getChildren().add(blueCircle);
    root.getChildren().add(greenCircle);
    root.getChildren().add(box1);

    // add the lines
    root.getChildren().add(line1);
    root.getChildren().add(line2);
    root.getChildren().add(line3);
    root.getChildren().add(line4);

    // bring the circles to the front of the lines
    redCircle.toFront();
    blueCircle.toFront();
    greenCircle.toFront();

    primaryStage.setScene(scene);
    primaryStage.show();
  }
  public static void main(String[] args) {
    launch(args);
  }
}