EVENT-DRIVEN PROGRAMMING AND ANIMATIONS - Introduction to Java Programming: Comprehensive Version - page 614

15.11.3 Timeline
PathTransition and FadeTransition define specialized animations. The Timeline
class can be used to program any animation using one or more KeyFrame s. Each KeyFrame
is executed sequentially at a specified time interval. Timeline inherits from Animation .
You can construct a Timeline using the constructor new Timeline(KeyFrame...
keyframes) . A KeyFrame can be constructed using

new KeyFrame(Duration duration, EventHandler<ActionEvent> onFinished)

The handler onFinished is called when the duration for the key frame is elapsed.
Listing 15.15 gives an example that displays a flashing text, as shown in Figure 15.20. The
text is on and off alternating to animate flashing.

L ISTING 15.15

TimelineDemo.java
1 import javafx.animation.Animation;
2 import javafx.application.Application;
3 import javafx.stage.Stage;
4 import javafx.animation.KeyFrame;
5 import javafx.animation.Timeline;
6 import javafx.event.ActionEvent;
7 import javafx.event.EventHandler;
8 import javafx.scene.Scene;
9 import javafx.scene.layout.StackPane;
10 import javafx.scene.paint.Color;
11 import javafx.scene.text.Text;
12 import javafx.util.Duration;
13
14 public class TimelineDemo extends Application {
15 @Override // Override the start method in the Application class
16 public void start(Stage primaryStage) {
17 StackPane pane = new StackPane();
18 Text text = new Text( 20 , 50 , "Programming is fun" );
19 text.setFill(Color.RED);
20

VideoNote
Flashing text

create a stack pane
create a text

pane.getChildren().add(text); // Place text into the stack pane

add text to pane

21
22 // Create a handler for changing text

23 EventHandler<ActionEvent> eventHandler = e -> {

handler for changing text

24 if (text.getText().length() != 0 ) {

25 text.setText( "" ); set text empty

26 }

27 else {

28 text.setText( "Programming is fun" ); set text

29 }

30 };

31
32 // Create an animation for alternating text
33 Timeline animation = new Timeline(
34 new KeyFrame(Duration.millis( 500 ), eventHandler));
35 animation.setCycleCount(Timeline.INDEFINITE);
36 animation.play(); // Start animation
37
38 // Pause and resume animation
39 text.setOnMouseClicked(e -> {
40 if (animation.getStatus() == Animation.Status.PAUSED) {
41 animation.play();
42 }
43 else {
44 animation.pause();

create a Timeline
create a KeyFrame for handler
set cycle count indefinite
play animation

resume animation

pause animation