Layout of Layer in GlassPane not working as expected - javafx

Question

I installed a Layer in the GlassPane like that:
MobileApplication.getInstance().getGlassPane().getLayers().add(myLayer);
Now I would expect the content of myLayer to be alligned in the center of the glassPane like it is when I add a layer to View:
view.getLayers().add(myLayer)
Although alignment is set to center I get the following result:
I noticed the layoutBounds of the layer added to glassPane being all "0", while the layoutBounds of the layer in view are identical to the view layoutBounds.
Furthermore I don't need to call layer.show() as stated in the gluon documentation ("Showing a Layer is then achieved either by calling show(), ..."), because the layer is immediately shown after it is added to a layer.
Am I missing something?

Answer 1

I suggest you have a look at the detailed documentation here, and not only to the JavaDoc.
There you will find a more detailed explanation on how layers can be added and created.
The preferred way is by using addLayerFactory(), like:
#Override
public void init() {
addViewFactory(BASIC_VIEW, () -> new BasicView(BASIC_VIEW));
addLayerFactory("My Layer", () -> new SidePopupView(new StackPane(new Button("Side"))));
}
The layer will be hidden unless you show it with MobileApplication.getInstance().showLayer("My Layer").
You can create your own Layer implementation, like:
private class MyLayer extends Layer {
private final Node root;
private final double size = 150;
public MyLayer() {
root = new StackPane(new Button("A custom layer"));
root.setStyle("-fx-background-color: white;");
getChildren().add(root);
getGlassPane().getLayers().add(this);
}
#Override
public void layoutChildren() {
root.setVisible(isShowing());
if (!isShowing()) {
return;
}
root.resize(size, size);
resizeRelocate((getGlassPane().getWidth() - size)/2, (getGlassPane().getHeight()- size)/2, size, size);
}
}
and add it as well to the factory:
addLayerFactory("My Layer", () -> new MyLayer());
But notice you will have to resize and relocate it, otherwise you will get 0,0 location as in your picture, and take care of its visibility.
Or you can use built-in layers, like SidePopupView, and you won't need to worry about these more low level details.