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javajavafxtooltipstyling

JavaFX How Can I Center a Tooltip on a Node?

I'm currently working on a form that features validation upon changing focus from one node to another and wish to display a tooltip centered above a node containing an error if one exists. I'm using the tooltip's show(Node ownerNode, double anchorX, double anchorY) method signature to specify which node I would like to attach it to and where to position it.

I've tried the following code: 

Tooltip tooltip = new Tooltip("Error"); 
tooltip.show(node, 0, 0);
double tooltipMiddle = tooltip.getWidth() / 2;
tooltip.hide(); 
double nodeMiddle = node.getWidth() / 2; 

//Gets the node's x and y position within the window
Bounds bounds = node.localToScene(node.getBoundsInLocal());  

//Tooltip's bottom-right corner is set to the anchor points, so I set x to
//the node's x coordinate plus half the width of the node plus half the width
//of the tooltip 
tooltip.show(node,
             bounds.getMinX() + nodeMiddle + tooltipMiddle, bounds.getMinY());

This has gotten me very close to the center, but it's still off. I've been all over the internet trying to find help, but I'm just not finding any, so I figured I'd ask here.
Any chance I could get some insight into why I'm not able to get this working how I'd like it?

Validation message screenshot

Solution

  • Code which I bring provides correct positioning of tooltip but is far from being perfect. It would take a lot of work to bring comprehensive solution (if you want we can discuss it). Going to the bottom I think you have a math problem and Tooltip class may not be the best option.

    import javafx.application.Application;
import javafx.geometry.Bounds;
import javafx.scene.Scene;
import javafx.scene.control.Button;
import javafx.scene.control.Label;
import javafx.scene.control.TextField;
import javafx.scene.layout.HBox;
import javafx.scene.layout.Pane;
import javafx.scene.layout.Region;
import javafx.scene.layout.StackPane;
import javafx.stage.Stage;

public class TooltipApp extends Application {

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

    @Override
    public void start(Stage stage) throws Exception {
        TextField textField = new TextField();
        textField.setPrefWidth(100.);

        Button button = new Button("Tooltip");

        HBox hBox = new HBox(textField, button);
        hBox.setMaxSize(Region.USE_PREF_SIZE, Region.USE_PREF_SIZE);

        Label label = new Label("Empty!");
        label.setVisible(false);
        Pane tooltipPane = new Pane(label);
        tooltipPane.setMouseTransparent(true);

        StackPane stackPane = new StackPane(hBox, tooltipPane);
        stackPane.setPrefSize(600., 400.);

        Scene scene = new Scene(stackPane);

        stage.setScene(scene);
        stage.show();

        button.setOnMouseClicked(event -> {
            if (label.isVisible()) {
                label.setVisible(false);
            } else {
                Bounds sceneBounds = textField.localToScene(textField.getBoundsInLocal());
                label.setLayoutX((sceneBounds.getMinX() + (sceneBounds.getWidth() / 2)) - (label.getWidth() / 2));
                label.setLayoutY(sceneBounds.getMinY() - label.getHeight());
                label.setVisible(true);
            }
        });
    }
}