How to Snapshot a Node not in FX-Application-Thread?

Question

Hi,
is it possible to take a snapshot of a node if the method is called outside the FX-Application-Thread?
If I try something like ...
  Task task = new Task<Void>() {
             @Override
             public Void call() {
             WritableImage nodeImage = wpImage_XXL.snapshot(paramsSnapShot, null);
        };i got this Exception.
java.lang.IllegalStateException: Not on FX application thread; currentThread
Any workaround, thanks in advance
Michael

Answer 1

You can't make this call from outside the FX Application Thread, and you really don't want to. If you could, you might end up with a partially-rendered image. Or perhaps worse, if the node were in the process of being resized, the width, height, and actual rendered content of the node could potentially be inconsistent. And there's probably a whole myriad of other things that could go wrong that I can't imagine.
From your application Thread (i.e. your Task), you can arrange for the code to be executed on the FX application thread using Platform.runLater(...):
Task task = new Task<Void>() {
  @Override
  public Void call() {
    Platform.runLater(new Runnable() {
      public void run() {
        WritableImage nodeImage = wpImage_XXL.snapshot(paramsSnapShot, null);
};If there is a significant amount of processing to be done once you've received your WritableImage (and I assume there is, and this is why this is being executed in a Task), then there is a version of the snapshot(...) method which takes a Callback. From the FX Application Thread, you can do something like this:
Callback<SnapshotResult, Void> processSnapshotCallback = new Callback<SnapshotResult, Void>() {
  @Override
  public Void call(SnapshotResult result) {
    final WritableImage image = result.getImage();
    // Launch Task to process image on new Thread
    return null ;
wpImage_XXL.snapshot(processSnapshotCallback, paramsSnapShot, null)