javaFX- what is getBoundsInLocal() ,getBoundsInParent() method?

Question

A image (here the node named hero) is moved according to the KEY pressed in keyboard. But a method named getBoundsInLocal() is used. I can't truly understand the purpose of this method . Does it helps to get the width and height of the image ?

private void moveHeroBy(int dx, int dy) {
    if (dx == 0 && dy == 0) return;

    final double cx = hero.getBoundsInLocal().getWidth()  / 2;
    final double cy = hero.getBoundsInLocal().getHeight() / 2;

    double x = cx + hero.getLayoutX() + dx;
    double y = cy + hero.getLayoutY() + dy;

    moveHeroTo(x, y);
}

private void moveHeroTo(double x, double y) {
    final double cx = hero.getBoundsInLocal().getWidth()  / 2;
    final double cy = hero.getBoundsInLocal().getHeight() / 2;

    if (x - cx >= 0 &&
        x + cx <= W &&
        y - cy >= 0 &&
        y + cy <= H) {
        hero.relocate(x - cx, y - cy);
    }
}

This method is called by an AnimationTimer by this way:

AnimationTimer timer = new AnimationTimer() {
        @Override
        public void handle(long now) {
            int dx = 0, dy = 0;

            if (goNorth) dy -= 1;
            if (goSouth) dy += 1;
            if (goEast)  dx += 1;
            if (goWest)  dx -= 1;
            if (running) { dx *= 3; dy *= 3; }

            moveHeroBy(dx, dy);
        }
    };
    timer.start();

I have found similar method named getBoundsInParent() . what do these two methods do & what are the differences ?

Answer 1

• getBoundsInLocal returns the bounds of a Node in it's own coordinate system.
• getBoundsInParent returns the bounds after adjusting them with depending on transforms/layoutX/layoutY.

Both can be used to determine the size, but which size you need is determined by the coordinate system you're using...

Example

Rectangle rect = new Rectangle(100, 200);
rect.setLayoutX(11);
rect.setLayoutY(33);
rect.setScaleX(2);

Pane root = new Pane();
root.getChildren().add(rect);
System.out.println(rect.getBoundsInLocal());
System.out.println(rect.getBoundsInParent());

prints

BoundingBox [minX:0.0, minY:0.0, minZ:0.0, width:100.0, height:200.0, depth:0.0, maxX:100.0, maxY:200.0, maxZ:0.0]
BoundingBox [minX:-39.0, minY:33.0, minZ:0.0, width:200.0, height:200.0, depth:0.0, maxX:161.0, maxY:233.0, maxZ:0.0]

For a untransformed ImageView you can determine the size by using the viewport's size or if this property is set to null the width/height of the image used with the ImageView