This question is a follow-up of this one.
The following code draws a Circle in an AnchorPane. The Circle is initialized with centerX=centerY=radius=50. When dragging mouse on the Circle, the Circle moves on the AnchorPane, such that its center coordinates remains at a constant position with respect to cursor position.
import javafx.application.Application;
import javafx.beans.Observable;
import javafx.beans.binding.Bindings;
import javafx.beans.binding.DoubleBinding;
import javafx.collections.FXCollections;
import javafx.collections.ObservableList;
import javafx.scene.Scene;
import javafx.scene.layout.AnchorPane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
public class HelloApplication extends Application {
private final AnchorPane mainPane=new AnchorPane();
double x=0,y=0;
double tx =0, ty =0;
int i=0;
// create list with an extractor:
ObservableList<Circle> circles =FXCollections.observableArrayList(circle1 -> new Observable[]{circle1.centerXProperty()});
Circle circle = new Circle(50,50,50);
@Override
public void start(Stage stage) {
// Set up stage for show!
Scene scene = new Scene(mainPane, 1200, 800);
stage.setTitle("Hello!");
stage.setScene(scene);
stage.show();
// set fill color.
circle.setFill(new Color(1, 0, 0, 0.5));
// set up onMousePressed listener.
circle.setOnMousePressed(mouseEvent -> {
x=mouseEvent.getX();
y=mouseEvent.getY();
});
// set up onMouseDragged listener.
circle.setOnMouseDragged(mouseEvent -> {
tx=x;
ty=y;
x=mouseEvent.getX();
y=mouseEvent.getY();
circle.setCenterX(circle.getCenterX()+x-tx);
circle.setCenterY(circle.getCenterY()+y-ty);
i++;
});
// add rectangle pane children.
mainPane.getChildren().addAll(circle);
// add rectangle to rectangles.
circles.add(circle);
DoubleBinding centerX = Bindings.createDoubleBinding(
() -> circles
.stream()
.mapToDouble(Circle::getCenterX)
.min()
.orElse(0),
circles
);
centerX.addListener((obs, oldMin, newMin) -> System.out.println("center X changed from " + oldMin + " to " + newMin+" , i = "+i));
}
public static void main(String[] args) {
launch();
}
}
A custom DoubleBinding centerX tracks the changes in the centerX of the Circle and prints the following message on console:
Min X changed from 50.0 to 58.0 , i = 0
where i is an index [the numbers are arbitrary and may change].
This message printing continues well up to approximately i=7000 and then stops. I would appreciate if someone gives me a hint as to why this happens and how to fix it. Thanks.
Addendum
The reason that I captured the min() of all Circle instances of circles is that I may have more than a Circle and I wish to capture the minimum position of the centerX values of these Circles. I included only one Circle instance in this example for simplicity.
