JavaFX Canvas-如何在绘制后重新绘制画布？

问题描述

我编写了此代码，可以在JavaFX Canvas上进行绘制。 它可以正常工作，但我不知道如何重新绘制画布（例如在Swing中）以重新开始在新画布上绘画。 这是我的代码，非常感谢您的帮助！ 马里奥

public class Main extends Application {

  private static final int WIDTH = 600;
  private static final int HEIGTH = 400;

  @Override
  public void start(Stage primaryStage) {
    //handling the canvas
    final Canvas canvas = new Canvas(WIDTH, HEIGTH);
    final GraphicsContext gc = canvas.getGraphicsContext2D();
    gc.setFill(Color.AQUA);
    gc.fill();
    //Painting with MouseDragged Event 
    canvas.setOnMouseDragged(event -> gc.fillOval(event.getX(),   event.getY(), 25, 25));
    //User a ColorPicke for Color of Painting
    ColorPicker cp = new ColorPicker();
    cp.setOnAction(e -> gc.setFill(cp.getValue()));
    //Layout
    BorderPane root = new BorderPane();
    HBox hb = new HBox(30);
    Button button = new Button("Clear all");

    button.setOnAction(e ->
    /*how to repaint the canvas*/
    System.out.println("How to repaint???"));

    hb.getChildren().addAll(cp, button);
    hb.setPrefHeight(200);
    hb.setAlignment(Pos.CENTER);
    root.setCenter(canvas);
    root.setBottom(hb);
    final Scene scene = new Scene(root);
    primaryStage.setTitle("Hello World!");
    primaryStage.setScene(scene);
    primaryStage.show();
  }

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