JavaFX:如何使用GraphicsContext.fillText？

import javafx.application.Application;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.canvas.GraphicsContext;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;
import javafx.stage.Stage;

public class Main extends Application {

    @Override
    public void start(Stage primaryStage) {
        Canvas canvas = new Canvas(400, 200);
        GraphicsContext gc = canvas.getGraphicsContext2D();

        gc.setFill(Color.RED);
        gc.setFont(javafx.scene.text.Font.font("Arial", 20));
        gc.fillText("Hello, JavaFX!", 50, 100);

        StackPane root = new StackPane();
        root.getChildren().add(canvas);

        primaryStage.setScene(new Scene(root, 400, 200));
        primaryStage.show();
    }

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