Scrollbars don't interact with scaled pane - javafx

Question

I have an anchorPane which is a child of a ScrollPane. Now I have a Button which scales the anchorPane. This means the button create a zoom effect. But when the anchorPane has another dimension the scrollPane doesn’t realize the changed size of anchorPane and the scrollbars do not become bigger or smaller. Here is my code:
public class View implements Observer{
private Model model;
private Stage stage;
private Button plus;
private Button minus;
Affine affine = new Affine();
ScrollPane scrollPane;
public View (Model model, Stage stage) {
model.addObserver(this);
this.model = model;
this.stage = stage;
this.plus = new Button("+");
this.minus = new Button("-");
HBox hBox = new HBox(2);
VBox vBox = new VBox();
AnchorPane anchorPane = new AnchorPane();
SVGPath svgTest = new SVGPath();
svgTest.setContent(model.getShapes());
anchorPane.getChildren().add(svgTest);
anchorPane.getTransforms().add(affine);
scrollPane = new ScrollPane(anchorPane);
scrollPane.setFitToHeight(true);
scrollPane.setFitToWidth(true);
scrollPane.setHbarPolicy(ScrollBarPolicy.AS_NEEDED);
scrollPane.setVbarPolicy(ScrollBarPolicy.AS_NEEDED);
hBox.getChildren().add(plus);
hBox.getChildren().add(minus);
SplitPane root = new SplitPane(scrollPane);
root.setOrientation(Orientation.VERTICAL);
root.setDividerPositions(0.85);
scrollPane.setVvalue( 1.0d );
root.getItems().add(hBox);
Scene scene = new Scene(root, 1000, 1000);
stage.setScene(scene);
stage.setTitle("myStage");
stage.show();
}
public Stage getStage() {
return stage;
}
public Button getZoomPlusButton() {
return plus;
}
public Button getZoomMinusButton() {
return minus;
}
public void zoomPlus() {
affine.append(new Scale(1.1, 1.1));
}
public void zoomMinus() {
affine.append(new Scale(0.9, 0.9));
}
#Override
public void update(Observable o, Object arg) {
}
}
How can I fix my problem?
Thank you in advance.

Answer 1

The documentation has
ScrollPane layout calculations are based on the layoutBounds rather than the boundsInParent (visual bounds) of the scroll node. If an application wants the scrolling to be based on the visual bounds of the node (for scaled content etc.), they need to wrap the scroll node in a Group.
So all you need is to wrap the scroll pane content in a Group:
scrollPane = new ScrollPane(new Group(anchorPane));