FX Experience Has Gone Read-Only

I've been maintaining FX Experience for a really long time now, and I love hearing from people who enjoy my weekly links roundup. One thing I've noticed recently is that maintaining two sites (FX Experience and JonathanGiles.net) takes more time than ideal, and splits the audience up. Therefore, FX Experience will become read-only for new blog posts, but weekly posts will continue to be published on JonathanGiles.net. If you follow @FXExperience on Twitter, I suggest you also follow @JonathanGiles. This is not the end - just a consolidation of my online presence to make my life a little easier!

tl;dr: Follow me on Twitter and check for the latest news on JonathanGiles.net.

This is a little bit novel – using FXExperience for a post that isn’t the weekly links! 🙂 I wish I could post here more often, but time constraints pretty much stop that in its tracks (even the weekly links take longer than I would like). Anyway, I often get asked about node picking in JavaFX, and if the Node.impl_pickNode(...) API will ever lose the ‘impl’ and become proper API.

The answer is: I don’t know – picking API is not ‘mine’ to worry about. Frankly, I’m barely qualified to discuss picking in any depth, as it is not something I use. Despite this, I will give my unqualified summary for those of you who are unfamiliar with what picking is: it is basically about getting the best matching (i.e. top-most) Node under a given x, y coordinate.

A few months back I was working in the Scene Builder code base to remove dependencies on these impl methods (and to generally clean it up to work on JDK 9 given all the changes due to project Jigsaw (i.e. modularity) and new APIs in JavaFX 9). One thing I had to replace was the use of Node.impl_pickNode(...). I ended up writing the code below, and given that I’m asked about this functionality a lot, I thought I would post it here in case others found it useful.

I should be very clear that this is not a performant implementation, and it is built with my naivety regarding picking (so I am happy to be sent suggestions for improving it). Nevertheless, I hope it helps.

public static Node pick(Node node, double sceneX, double sceneY) {
    Point2D p = node.sceneToLocal(sceneX, sceneY, true /* rootScene */);

    // check if the given node has the point inside it, or else we drop out
    if (!node.contains(p)) return null;

    // at this point we know that _at least_ the given node is a valid
    // answer to the given point, so we will return that if we don't find
    // a better child option
    if (node instanceof Parent) {
        // we iterate through all children in reverse order, and stop when we find a match.
        // We do this as we know the elements at the end of the list have a higher
        // z-order, and are therefore the better match, compared to children that
        // might also intersect (but that would be underneath the element).
        Node bestMatchingChild = null;
        List<Node> children = ((Parent)node).getChildrenUnmodifiable();
        for (int i = children.size() - 1; i >= 0; i--) {
            Node child = children.get(i);
            p = child.sceneToLocal(sceneX, sceneY, true /* rootScene */);
            if (child.isVisible() && !child.isMouseTransparent() && child.contains(p)) {
                bestMatchingChild = child;

        if (bestMatchingChild != null) {
            return pick(bestMatchingChild, sceneX, sceneY);

    return node;