How to put marks in a scrollbar - javafx

Question

I'm implementing a search feature and I would like to highlight the positions of the matches in the scrollbar of my table view.
Is there any way to show color marks in a scrollbar in JavaFX?

Answer 1

If you get access to the ScrollBar after it has been layouted for the first time, you can add the marks to the track:
public class ScrollBarMark {
private final Rectangle rect;
private final DoubleProperty position = new SimpleDoubleProperty();
public ScrollBarMark() {
rect = new Rectangle(5, 5, Color.RED.deriveColor(0, 1, 1, 0.5));
rect.setManaged(false);
}
public void attach(ScrollBar scrollBar) {
StackPane sp = (StackPane) scrollBar.lookup(".track");
rect.widthProperty().bind(sp.widthProperty());
sp.getChildren().add(rect);
rect.layoutYProperty().bind(Bindings.createDoubleBinding(() -> {
double height = sp.getLayoutBounds().getHeight();
double visibleAmout = scrollBar.getVisibleAmount();
double max = scrollBar.getMax();
double min = scrollBar.getMin();
double pos = position.get();
double delta = max - min;
height *= 1 - visibleAmout / delta;
return height * (pos - min) / delta;
},
position,
sp.layoutBoundsProperty(),
scrollBar.visibleAmountProperty(),
scrollBar.minProperty(),
scrollBar.maxProperty()));
}
public final double getPosition() {
return this.position.get();
}
public final void setPosition(double value) {
this.position.set(value);
}
public final DoubleProperty positionProperty() {
return this.position;
}
public void detach() {
StackPane parent = (StackPane) rect.getParent();
if (parent != null) {
parent.getChildren().remove(rect);
rect.layoutYProperty().unbind();
rect.widthProperty().unbind();
}
}
}
Right now this only works with vertical ScrollBars.
#Override
public void start(Stage primaryStage) {
ScrollBar scrollBar = new ScrollBar();
scrollBar.setOrientation(Orientation.VERTICAL);
scrollBar.setMax(100);
scrollBar.setVisibleAmount(50);
scrollBar.valueProperty().addListener((a,b,c) -> System.out.println(c));
StackPane root = new StackPane();
root.getChildren().add(scrollBar);
Scene scene = new Scene(root, 200, 500);
// do layout
root.applyCss();
root.layout();
ScrollBarMark mark1 = new ScrollBarMark();
ScrollBarMark mark2 = new ScrollBarMark();
mark1.attach(scrollBar);
mark2.attach(scrollBar);
mark1.setPosition(50);
mark2.setPosition(75);
primaryStage.setScene(scene);
primaryStage.show();
}