RECURSION - Introduction to Java Programming: Comprehensive Version - page 724

20 e -> trianglePane.setOrder(Integer.parseInt(tfOrder.getText())));
21 tfOrder.setPrefColumnCount( 4 );
22 tfOrder.setAlignment(Pos.BOTTOM_RIGHT);
23
24 // Pane to hold label, text field, and a button
25 HBox hBox = new HBox( 10 );
26 hBox.getChildren().addAll( new Label( "Enter an order: " ), tfOrder);
27 hBox.setAlignment(Pos.CENTER);
28
29 BorderPane borderPane = new BorderPane();
30 borderPane.setCenter(trianglePane);
31 borderPane.setBottom(hBox);
32
33 // Create a scene and place it in the stage
34 Scene scene = new Scene(borderPane, 200 , 210 );
35 primaryStage.setTitle( "SierpinskiTriangle" ); // Set the stage title
36 primaryStage.setScene(scene); // Place the scene in the stage
37 primaryStage.show(); // Display the stage
38
39 scene.widthProperty().addListener(ov -> trianglePane.paint());
40 scene.heightProperty().addListener(ov -> trianglePane.paint());
41 }
42
43

listener for text field

hold label and text field

listener for resizing

/** Pane for displaying triangles */

44 static class SierpinskiTrianglePane extends Pane {

45 private int order = 0 ;

46
47 /** Set a new order */
48 public void setOrder( int order) {
49 this .order = order;
50 paint();
51 }
52
53 SierpinskiTrianglePane() {
54 }
55
56 protected void paint() {
57 // Select three points in proportion to the pane size
58 Point2D p1 = new Point2D(getWidth() / 2 , 10 );
59 Point2D p2 = new Point2D( 10 , getHeight() - 10 );
60 Point2D p3 = new Point2D(getWidth() - 10 , getHeight() - 10 );
61
62

three initial points

this .getChildren().clear(); // Clear the pane before redisplay clear the pane

63
64 displayTriangles(order, p1, p2, p3);

draw a triangle

65 }
66
67 private void displayTriangles( int order, Point2D p1,
68 Point2D p2, Point2D p3) {
69 if (order == 0 ) {
70 // Draw a triangle to connect three points
71 Polygon triangle = new Polygon();
72 triangle.getPoints().addAll(p1.getX(), p1.getY(), p2.getX(),
73 p2.getY(), p3.getX(), p3.getY());
74 triangle.setStroke(Color.BLACK);
75 triangle.setFill(Color.WHITE);
76
77

create a triangle

this .getChildren().add(triangle);

78 }
79 else {