Java 设置画布布局

如何在场景中间获得白色矩形。我想保留我自己的代码以及它的高度和宽度。可能应该使用它来设置X和Y布局。但我不知道怎么做。当我设置它们时，它会从左上角调整大小

代码：

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试试这个例子。。。对于场景中间的位置，可以使用以下公式计算宽度：

layoutxcanvas=（widthscene/2）-（widthcanvas/2）

layoutycanvas=（高度场景/2）-（高度画布/2）

Pane paneCanvas = new Pane();

          final Canvas canvas = new Canvas();
          paneCanvas.setStyle("-fx-background-color: white;");
          canvas.setHeight(32);
          canvas.setWidth(32);

          paneCanvas.getChildren().add(canvas);
          primaryStage.setTitle("Hello World!");
          primaryStage.setScene(scene);
          primaryStage.show();

import java.awt.Graphics2D;
import java.awt.Paint;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.canvas.Canvas;
import javafx.scene.control.Button;
import javafx.scene.layout.Pane;
import javafx.scene.layout.StackPane;
import javafx.scene.paint.Color;

import javafx.stage.Stage;

public class JavaFXApplication1 extends Application {

    @Override
    public void start(Stage primaryStage) {
       Pane paneCanvas = new Pane();

          final Canvas canvas = new Canvas();
          paneCanvas.setStyle("-fx-background-color: black;");

          canvas.setHeight(32);
          canvas.setWidth(32);
          canvas.getGraphicsContext2D().setFill(Color.WHITE);
          canvas.getGraphicsContext2D().fillRect(0, 0, 32, 32);

          canvas.setLayoutX((300/2)-(32/2));
          canvas.setLayoutY((300/2)-(32/2));

          paneCanvas.getChildren().add(canvas);
          Scene scene=new Scene(paneCanvas,300,300);
          primaryStage.setTitle("Hello World!");
          primaryStage.setScene(scene);
          primaryStage.show();
    }

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
        launch(args);
    }