CODEWITHSUNDEEP
javajavafx
Lai Yu-Hsuan
Lai Yu-Hsuan

Reputation: 28081

Timeline doesn't work with 'some' durations

I have this working code:

Duration duration = Duration.millis(1000 / 30.0);
videoTick = new Timeline(new KeyFrame(duration, new EventHandler<ActionEvent>() {
    public void handle(ActionEvent actionEvent) {
            System.out.println("tick");
        }
    }));
videoTick.setCycleCount(Animation.INDEFINITE);
videoTick.playFromStart();

Perfectly. But once I change the duration slightly:

Duration duration = Duration.millis(1000 / 30.1);

It doesn't work anymore! Am I insane or JavaFx totally broken? How to work around it?

Edit: I know this bug looks not to make ANY sense, but it just happened in front of me. I provided the minimum code to reproduce it. 

import javafx.animation.*;
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.util.Duration;
import javafx.stage.Stage;

public class Ticker extends Application {
    private Timeline videoTick;

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

    @Override
    public void start(final Stage primaryStage) {
        Duration duration = Duration.millis(1000 / 30.0);
        videoTick = new Timeline(new KeyFrame(duration, new EventHandler<ActionEvent>() {
            public void handle(ActionEvent actionEvent) {
                System.out.println("Tick");
            }
        }));
        videoTick.setCycleCount(Animation.INDEFINITE);
        videoTick.playFromStart();
    }
}

Then change the 30.0 to 30.1.

EDIT 2: Ok, here is a (partial) workaround: Timeline#play() works when Timeline#playFromStart() doesn't.(EDIT 4: sorry, this doesn't work. Obviously I'm too tired.)

But the problem isn't solved: what if you really need playFromStart? And more importantly, why it doesn't work with 1000/30.1?

EDIT 3:

I reproduced it on OSX 10.8 + Java/JavaFx 1.7.0_17 and Java/JavaFx 1.7.0_21.

Upvotes: 3

Views: 1227

Answers (1)

jewelsea
jewelsea

Reputation: 159341

Java 7 Bug

It's a bug with JavaFX in Java 7. I created RT-31027 in the JavaFX issue tracker to track this issue.

I was able to reproduce this (no tick output) using Java 1.7.0_21, OSX 10.8 when compiling and running from the command line.

Sorry for earlier mis-report that it was working in Java 1.7.0_21 (I had made a setup error with java version switching in my IDE).

Fixed in Java 8

It does work (ticks are output) in Java8b92, so the bug would appear to have been fixed in a later JavaFX build. Java 8 early access builds are available. So as a workaround, you could use Java 8.

Alternate Implementation

For these kinds of animations, which happen very often, you could also consider using an AnimationTimer instead.

Update

RT-31027, the issue tracker record I created to track this, was closed as fixed in 8.0, with the comment "Only critical fixes are backported to 2.2, so closing this as fixed".

Upvotes: 1

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