JavaFX scrollpane – check the displayed components

I want to know if there is a scrollpane attribute in JavaFX 8 that can be used to listen for components currently displayed at a given time

Solution

You can check whether the node is visible:

private List<Node> getVisibleNodes(ScrollPane pane) {
    List<Node> visibleNodes = new ArrayList<>();
    Bounds paneBounds = pane.localToScene(pane.getBoundsInParent());
    if (pane.getContent() instanceof Parent) {
        for (Node n : ((Parent) pane.getContent()).getChildrenUnmodifiable()) {
            Bounds nodeBounds = n.localToScene(n.getBoundsInLocal());
            if (paneBounds.intersects(nodeBounds)) {
                visibleNodes.add(n);
            }
        }
    }
    return visibleNodes;
}

This method returns a list of all visible nodes All it does is compare the scene coordinates of scrollpane and its children

If you want to create your own observablelist in the property:

private ObservableList<Node> visibleNodes;

…

visibleNodes = FXCollections.observableArrayList();

ScrollPane pane = new ScrollPane();
pane.vvalueproperty().addListener((obs) -> {
    checkVisible(pane);
});
pane.hvalueproperty().addListener((obs) -> {
    checkVisible(pane);
});

private void checkVisible(ScrollPane pane) {
    visibleNodes.setAll(getVisibleNodes(pane));
}

For complete code, see bitbucket