Tooltip isn't being displayed on ScrollPane - javafx

Question

Following the tutorial here I tried to create a Tooltip on a ScrollPane using the following code:
final ScrollPane scroll = new ScrollPane();
scroll.addEventHandler(MouseEvent.MOUSE_MOVED, new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent t) {
pointer = MouseInfo.getPointerInfo();
point = pointer.getLocation();
color = robot.getPixelColor((int) point.getX(), (int) point.getY());
Tooltip tooltip = new Tooltip();
tooltip.setText(" " + color);
tooltip.activatedProperty();
scroll.setTooltip(tooltip);
System.out.println("Color at: " + point.getX() + "," + point.getY() + " is: " + color);
}
});
The tooltip however refuses to show itself on the ScrollPane but the output of "Color at: ..." is being printed so I am sure that handle is being called.
EDIT : On the suggestion of jewelsea , I tried putting the eventHandler on the content ,rather than the pane, but to no effect.

Answer 1

If I understand what you're trying to do, you really only need to install the tooltip once, and then just modify its text as the mouse moves.
This works for me:
import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.control.ScrollPane;
import javafx.scene.control.Tooltip;
import javafx.scene.image.Image;
import javafx.scene.image.ImageView;
import javafx.scene.image.PixelReader;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.BorderPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;
public class ImageTooltipTest extends Application {
#Override
public void start(Stage primaryStage) {
BorderPane root = new BorderPane();
Image image = new Image("http://www.publicdomainpictures.net/pictures/30000/velka/tropical-paradise.jpg");
final ImageView imageView = new ImageView();
imageView.setImage(image);
final ScrollPane scroller = new ScrollPane();
scroller.setContent(imageView);
final Tooltip tooltip = new Tooltip();
scroller.setTooltip(tooltip);
scroller.getContent().addEventHandler(MouseEvent.MOUSE_MOVED, event -> {
Image snapshot = scroller.getContent().snapshot(null, null);
int x = (int) event.getX();
int y = (int) event.getY();
PixelReader pixelReader = snapshot.getPixelReader();
Color color = pixelReader.getColor(x, y);
String text = String.format("Red: %.2f%nGreen: %.2f%nBlue: %.2f",
color.getRed(),
color.getGreen(),
color.getBlue());
tooltip.setText(text);
});
root.setCenter(scroller);
Scene scene = new Scene(root, 800, 600);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}