JavaFX setOnShown fires before window is visible - javafx

Question

I'm trying to set the minimum height of a window to the height of the scene it contains + the title bar height (so after showing the window, there's no possibility to shrink it more). Following this answer I wrote:
stage.setOnShown(event -> {
stage.setMinHeight(stage.getHeight());
});
It doesn't seem to work though because when the event is fired the window is not even shown on screen and its height is still equal to the height of the scene (title bar is not taken into consideration). My question is then - how to run the code when window is actually visible on the screen?

Answer 1

You can force the root of the scene to be laid out, and then size the stage to the scene's size:
stage.setOnShown(e -> {
stage.getScene().getRoot().layout();
stage.sizeToScene();
stage.setMinHeight(stage.getHeight());
});
Here's a SSCCE:
import javafx.application.Application;
import javafx.geometry.Insets;
import javafx.scene.Scene;
import javafx.scene.control.Label;
import javafx.scene.layout.VBox;
import javafx.stage.Stage;
public class StageSizeTest extends Application {
#Override
public void start(Stage primaryStage) {
primaryStage.setOnShown(e -> {
primaryStage.getScene().getRoot().layout();
primaryStage.sizeToScene();
System.out.printf("[%.1f, %.1f]%n", primaryStage.getWidth(), primaryStage.getHeight());
primaryStage.setMinWidth(primaryStage.getWidth());
primaryStage.setMinHeight(primaryStage.getHeight());
});
VBox root = new VBox(10,
new Label("Test one"),
new Label("Another test"),
new Label("Another really long label to give the scene some width"),
new Label("Bottom label"));
root.setPadding(new Insets(10));
Scene scene = new Scene(root);
primaryStage.setScene(scene);
primaryStage.show();
}
public static void main(String[] args) {
launch(args);
}
}