Sam De Meyer Sam De Meyer - 3 months ago 23
Java Question

Handle mouse event anywhere with JavaFX

I have a JavaFX application, and I would like to add an event handler for a mouse click anywhere within the scene. The following approach works ok, but not exactly in the way I want to. Here is a sample to illustrate the problem:

public void start(Stage primaryStage) {
root = new AnchorPane();
scene = new Scene(root,500,200);
scene.setOnMousePressed(new EventHandler<MouseEvent>() {
@Override
public void handle(MouseEvent event) {
System.out.println("mouse click detected! "+event.getSource());
}
});

Button button = new Button("click here");
root.getChildren().add(button);

primaryStage.setScene(scene);
primaryStage.show();
}


If I click anywhere in empty space, the
EventHandler
invokes the
handle()
method, but if i click the
button
, the
handle()
method is not invoked. There are many buttons and other interactive elements in my application, so I need an approach to catch clicks on those elements as well without having to manually add a new handler for every single element.

Answer

You can add an event filter to the scene with addEventFilter(). This will be called before the event is consumed by any child controls. Here's what the code for the event filter looks like.

scene.addEventFilter(MouseEvent.MOUSE_PRESSED, new EventHandler<MouseEvent>() {
    @Override
    public void handle(MouseEvent mouseEvent) {
        System.out.println("mouse click detected! " + mouseEvent.getSource());
    }
});