获取使用属性绑定 Javafx 的圆心

Question

如何将圆圈绑定到窗格后找到圆心？

circle.centerXProperty().bind(pane.widthProperty().divide(2));
circle.centerYProperty().bind(pane.heightProperty().divide(2));

我使用上面的代码来绑定圆的属性。但是，如果我想获取中心的 X 和 Y 坐标，它们的值是0.00.

我用了circle.getCenterX();和circle.centerXProperty().

谁能帮我弄清楚如何获得正确的圆心？

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.stage.Stage;
import javafx.scene.text.*;
import java.lang.Math;
public class CharactersAroundCircle extends Application {

public void start(Stage primaryStage){
String str = "Welcome To Java";
Circle circle = new Circle();
System.out.println(str.length());
Pane pane = new Pane();
circle.setRadius(125);
circle.centerXProperty().bind(pane.widthProperty().divide(2));
circle.centerYProperty().bind(pane.heightProperty().divide(2));
circle.setStroke(Color.BLACK);
circle.setFill(new Color(1,1,1,0));

Text text = new Text();
text.setText(String.valueOf(str.charAt(0)));
text.setStroke(Color.BLACK);
text.setFont(Font.font("Times New Roman", 20));
// text.setX(circle.getCenterX() + Math.toRadians(Math.sin(360 / str.length()) * circle.getRadius()));
// text.setY(circle.getCenterY() + Math.toRadians(Math.cos(360 / str.length()) * circle.getRadius()));
text.setX(circle.getCenterX() + 100);
text.setY(circle.getCenterY() + 100);
System.out.println(circle.centerXProperty());
System.out.println(circle.getCenterY());
pane.getChildren().add(text);

pane.getChildren().add(circle);
Scene scene = new Scene(pane, 300, 300);
primaryStage.setTitle("CharactersAroundCircle");
primaryStage.setScene(scene);
primaryStage.show();
}
}

Answer 1

您的问题是您无法动态访问圆圈值。你可以通过使用绑定(如 pane.heightProperty(或使用 ChangeListener 来解决此问题：

import javafx.application.Application;
import javafx.beans.value.ChangeListener;
import javafx.beans.value.ObservableValue;
import javafx.scene.Scene;
import javafx.scene.layout.Pane;
import javafx.scene.paint.Color;
import javafx.scene.shape.Circle;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;
public class CharactersAroundCircle extends Application implements ChangeListener<Number> {
Circle circle;
Text text;
String str;
public static void main(String[] args) {
launch(args);
}
@Override
public void start(Stage primaryStage) {
str = "Welcome To Java";
circle = new Circle();
System.out.println(str.length());
Pane pane = new Pane();
circle.setRadius(125);
circle.centerXProperty().bind(pane.widthProperty().divide(2));
circle.centerYProperty().bind(pane.heightProperty().divide(2));
pane.widthProperty().addListener(this);
pane.heightProperty().addListener(this);
circle.setStroke(Color.BLACK);
circle.setFill(new Color(1, 1, 1, 0));
text = new Text();
text.setText(String.valueOf(str.charAt(0)));
text.setStroke(Color.BLACK);
text.setFont(Font.font("Times New Roman", 20));
pane.getChildren().add(text);
pane.getChildren().add(circle);
Scene scene = new Scene(pane, 300, 300);
primaryStage.setTitle("CharactersAroundCircle");
primaryStage.setScene(scene);
primaryStage.show();
}
@Override
public void changed(ObservableValue<? extends Number> observable, Number oldValue, Number newValue) {
text.setX(circle.getCenterX() + Math.toRadians(Math.sin(360 / str.length()) * circle.getRadius()));
text.setY(circle.getCenterY() + Math.toRadians(Math.cos(360 / str.length()) * circle.getRadius()));
}
}