JavaFX rectangle width animation

Question

just a question... is it possible to show the change of the width of a rectangle as an animation? The rectangle itself is a statusbar so a scale in both x directions does not do the job.

thx

Answer 1

One method would be to animate the width modification within a Timeline as opposed to scaling in both directions. You can simulate the direction by modifying the alignment of the Rectangle's parent

Alignment values:

• Pos.CENTER : Appears as though the change is occurring in both directions
• Pos.CENTER_LEFT: Appears as though the change is occurring from the right
• Pos.CENTER_RIGHT: Appears as though the change is occurring from the left

By experimenting with alignments you can choose the one that best fits your current status bar

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Visual representation:

Order of alignment: Right | Center | Left

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SSCCE:

public class RectangleWidthAnimation extends Application{
    @Override
    public void start(Stage primaryStage) throws Exception {
        Rectangle statusBar = new Rectangle(300, 100);
        Button animationButton = new Button("Animate width decrease by 25");
        animationButton.setOnAction(event -> {
            System.out.println("Animation start: width = " + statusBar.getWidth());
            KeyValue widthValue = new KeyValue(statusBar.widthProperty(), statusBar.getWidth() - 25);
            KeyFrame frame = new KeyFrame(Duration.seconds(2), widthValue);
            Timeline timeline = new Timeline(frame);
            timeline.play();
            timeline.setOnFinished(finishedEvent -> System.out.println("Animation end: width = " + statusBar.getWidth()));
        });

        VBox container = new VBox(10, statusBar, animationButton);

        //Experiment with these alignments
        container.setAlignment(Pos.CENTER);
        //container.setAlignment(Pos.CENTER_LEFT);
        //container.setAlignment(Pos.CENTER_RIGHT);

        primaryStage.setScene(new Scene(container, 350, 150));
        primaryStage.show();
    }
}

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An alternative to the above could be to use transitions, which you can read about here