JavaFX transparent stage and scene

Question

I'm new to JavaFX , i'm trying to create a transparent scene and stage the problem is when I add nodes like images and labels , the scene is no longer transparent this is my code

package application;




import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.fxml.FXMLLoader;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
import javafx.scene.Parent;
import javafx.scene.Scene;
import javafx.scene.input.MouseEvent;



public class Main extends Application { 

    private double xOffset = 0;
    private double yOffset = 0;
    public void start(Stage primaryStage) throws Exception {
    try{ 

        Parent root ;
        root = FXMLLoader.load(getClass().getResource("/View/Authentification.fxml"));

        primaryStage.initStyle(StageStyle.TRANSPARENT);
        Scene scene = new Scene(root);
        scene.setFill(null);

         root.setOnMousePressed(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent event) {
                    xOffset = event.getSceneX();
                    yOffset = event.getSceneY();
                }
            });
            root.setOnMouseDragged(new EventHandler<MouseEvent>() {
                @Override
                public void handle(MouseEvent event) {
                    primaryStage.setX(event.getScreenX() - xOffset);
                    primaryStage.setY(event.getScreenY() - yOffset);
                }
            });


        primaryStage.setScene(scene);

    primaryStage.show();}
     catch(Exception e) {
            e.printStackTrace();
        }  
    }
    public static void main(String[] args) {
        launch(args);
    }
}

and this is my xml code :

<?xml version="1.0" encoding="UTF-8"?>

<?import javafx.scene.control.Label?>
<?import javafx.scene.image.Image?>
<?import javafx.scene.image.ImageView?>
<?import javafx.scene.layout.AnchorPane?>
<?import javafx.scene.text.Font?>

<AnchorPane xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1">

      <AnchorPane layoutY="94.0" prefHeight="417.0" prefWidth="363.0" style="-fx-background-color: #3D4966;"/>
      <AnchorPane layoutX="-1.0" prefHeight="82.0" prefWidth="363.0" style="-fx-background-color: #3D4966;">
      <children>
      <Label layoutX="280.0" layoutY="70.0" text="Fermer" textFill="#eee5e5">
         <font>
            <Font name="System Bold" size="12.0" />
         </font>
      </Label>
      <ImageView layoutX="288.0" layoutY="22.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@../images/Shutdown.png" />
         </image>
      </ImageView>
      <Label layoutX="146.0" layoutY="61.0" prefHeight="17.0" prefWidth="92.0" text="crée un compte" textFill="#eee5e5">
         <font>
            <Font name="System Bold" size="12.0" />
         </font>
      </Label>
      <ImageView layoutX="167.0" layoutY="21.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@../images/Add_User.png" />
         </image>
      </ImageView>
      <ImageView layoutX="50.0" layoutY="21.0" pickOnBounds="true" preserveRatio="true">
         <image>
            <Image url="@../images/User.png" />
         </image>
      </ImageView>
      <Label layoutX="50.0" layoutY="62.0" text="Ce connecter" textFill="#eee5e5">
         <font>
            <Font name="System Bold" size="12.0" />
         </font>
      </Label>
   </children>
   </AnchorPane>


</AnchorPane>

i tried a lot of other codes but nothing seems to work these are some screenshots with nodes

without nodes

Answer 1

If you create one or more controls (specifically, any instance of Control or a subclass), the default stylesheet is applied to the scene. This sets the background color of the root of the scene to a non-transparent "very light grey" (basically 26.4% lighter than #ececec).

(Specifically, the default stylesheet contains the following:

.root {
    /***************************************************************************
     *                                                                         *
     * The main color palette from which the rest of the colors are derived.   *
     *                                                                         *
     **************************************************************************/

    /* A light grey that is the base color for objects.  Instead of using
     * -fx-base directly, the sections in this file will typically use -fx-color.
     */
    -fx-base: #ececec;

    /* A very light grey used for the background of windows.  See also
     * -fx-text-background-color, which should be used as the -fx-text-fill
     * value for text painted on top of backgrounds colored with -fx-background.
     */
    -fx-background: derive(-fx-base,26.4%);

    /* ... */

    -fx-background-color: -fx-background;

}

The source for the current version of the default stylesheet (at the time of writing) can be found at http://hg.openjdk.java.net/openjfx/9/rt/file/c734b008e3e8/modules/javafx.controls/src/main/resources/com/sun/javafx/scene/control/skin/modena/modena.css).

So you need to make the root of the scene transparent too.

You can do this using inline CSS, either in the FXML:

<AnchorPane style="-fx-background-color: transparent ;" xmlns="http://javafx.com/javafx/8.0.111" xmlns:fx="http://javafx.com/fxml/1">

or in Java:

    Parent root ;
    root = FXMLLoader.load(getClass().getResource("/View/Authentification.fxml"));
    root.setStyle("-fx-background-color: transparent ;");

or you can do it in an external style sheet:

.root {
    -fx-background-color: transparent ;
}