如何将已绘制在javaFX画布上的某些文本置于圆圈的中心？

import javafx.application.Application;
import javafx.scene.Group;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.scene.text.Text;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
        // 创建JavaFX画布
        Canvas canvas = new Canvas(400, 400);
        GraphicsContext gc = canvas.getGraphicsContext2D();

        // 创建圆圈对象
        double centerX = 200;
        double centerY = 200;
        double radius = 100;
        gc.setFill(Color.BLUE);
        gc.fillOval(centerX - radius, centerY - radius, radius * 2, radius * 2);

        // 创建文本对象
        String textContent = "Hello World";
        Font font = Font.font("Arial", 20);
        Text text = new Text(textContent);
        text.setFont(font);

        // 获取文本的宽度和高度
        double textWidth = text.getLayoutBounds().getWidth();
        double textHeight = text.getLayoutBounds().getHeight();

        // 计算文本的位置
        double textX = centerX - textWidth / 2;
        double textY = centerY + textHeight / 2;

        // 将文本添加到画布上
        gc.setFill(Color.WHITE);
        gc.fillText(textContent, textX, textY);

        // 创建JavaFX场景
        Group root = new Group();
        root.getChildren().add(canvas);
        Scene scene = new Scene(root, 400, 400);

        // 设置舞台并显示
        primaryStage.setTitle("JavaFX Circle with Text");
        primaryStage.setScene(scene);
        primaryStage.show();
    }

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