JavaFX：如何使底层节点可访问？

Question

I have a Pane and a VBox inside of a StackPane . I added the Pane first and the VBox on top of it. The VBox includes several kes that in turn have Button s as children. I use the normal Pane as a "canvas" to position Line s on it. The Line s as well as the Button s need to be interactive. So by clicking on them they shall for example change their color. But at the moment the Pane and its Line objects are shown but they are covered by the VBox so I can not interact with them but only with the Button s.

How can I provide that I can interact with the Line as well, though they are in a lower layer of the StackPane ?

Answer 1

They are covered cause the VBOX is in front of the Pane.

First Way:

You can setVisible(false) the VBox so the Pane can be accessible and then setVisible(true) the VBox again.

Second Way:

You can use methods called toBack(); and toFront(); and bring a Node back or front to the hierarchy:

vBox.toBack(); //the the vBox goes back to the hierarchy,it is like zOrder in html

and then use:

 vBox.toFront(); //to bring the vBox again in front.

Finally:

You can somewhere provide a ToggleButton that when is pressed the VBox is appearing and when is not pressed the VBox is disappeared.

Answer 2

You can set the pickOnBoundsProperty of your container Node s ( VBox and HBox ) to false .

Defines how the picking computation is done for this node when triggered by a MouseEvent or a contains function call. If pickOnBounds is true, then picking is computed by intersecting with the bounds of this node, else picking is computed by intersecting with the geometric shape of this node.

As result, "transparent" areas of the HBox and the VBox will not register the click event.

Example:

public class Main extends Application {
    @Override
    public void start(Stage primaryStage) {
        try {
            BorderPane root = new BorderPane();
            Scene scene = new Scene(root,400,400);
            scene.getStylesheets().add(getClass().getResource("application.css").toExternalForm());

            Pane pane = new Pane();
            pane.setStyle("-fx-background-color:red;");
            StackPane sp = new StackPane();
            VBox vbox = new VBox();

            HBox hbox = new HBox();
            hbox.setSpacing(30);


            for (int i = 0; i< 5; i++) {
                Button b = new Button("Button");
                b.setOnAction(e -> System.out.println("Button clicked"));
                hbox.getChildren().add(b);
            }

            vbox.getChildren().add(hbox);
            sp.getChildren().addAll(pane, vbox);

            Line line = new Line(10, 10, 500, 10);
            line.setStrokeWidth(3);
            pane.getChildren().add(line);
            line.setOnMouseClicked(e -> {
                System.out.println("Line Clicked!");
            });

            // Set pickOnBounds to vbox and hbox
            vbox.setPickOnBounds(false);
            hbox.setPickOnBounds(false);
            root.setCenter(sp);

            primaryStage.setScene(scene);
            primaryStage.show();
        } catch(Exception e) {
            e.printStackTrace();
        }
    }

    public static void main(String[] args) {
        launch(args);
    }
}