在拖动Javafx上移动形状-形状不断重置

Question

I'm trying to get a simple rectangle to move on drag. I have it moving, but when I try to drag again, it first reverts back to the initial position before the initial drag. I've tried using StackPane, FlowPane, Pane, and AnchorPane.

  public View getView() {
        View view = new View("Test View");
        view.setName(name);
        Pane pane = new Pane();

        rect.setOnMousePressed((MouseEvent me) -> {
            xVal = me.getSceneX();
            yVal = me.getSceneY();
            System.out.println("PRESSED_" + Double.toString(rect.getX()));
        });

        rect.setOnMouseReleased((MouseEvent me) -> {
            System.out.println("RELEASE_" + Double.toString(rect.getX()));
        });

        rect.setOnMouseDragged((MouseEvent me) ->{
            final double diffX = me.getSceneX() - xVal;
            final double diffY = me.getSceneY() - yVal;
            System.out.println("SET_" + Double.toString(rect.getX()));
            rect.setX(diffX);
            rect.setY(diffY);
        });

        pane.getChildren().add(rect);
        view.setCenter(pane);
        return view;
    }

Note: rect , xVal , yVal are all class properties.

The issue again is that I can move the rectangle just fine. However when I try to move again, the rectangle seems to jump back to the original point of the rectangle. You can see in the following image where it seems to revert:

Note: The fact that the diffX and diffY are final isn't a problem here.

Another Note: I have also tried setTranslate() as well as getTransforms().add() ...

Answer 1

OK so I was fiddling around with it and I figured it out that every time I press down, the X and Y coordinates of the rectangle are calibrated at (0,0) . So all I had to do was to set xVal and yVal to 0 in the initial mouse press event. However, this makes xVal and yVal to be trivial. Thus, they can be deleted. Not really sure if this was the best solution, but it works for me:

    rect.setOnMousePressed((MouseEvent me) -> {
        System.out.println("PRESSED_" + Double.toString(rect.getX()));
    });

    rect.setOnMouseReleased((MouseEvent me) -> {
        System.out.println("RELEASE_" + Double.toString(rect.getX()));
    });

    rect.setOnMouseDragged((MouseEvent me) ->{
        double diffX = me.getX() - rect.getWidth() / 2;
        double diffY = me.getY() - rect.getHeight() / 2;
        System.out.println("SET_" + Double.toString(rect.getX()));
        rect.setX(diffX);
        rect.setY(diffY);
    });