Thread: Dragging Undercoated Window Causes Glitching

Hey could use a little help on a Post-It-Note project I'm just finishing up. It's a small program that only has one other class than Main.

The PostIt class creates a new Undercoated JavaFX Stage and calls stage.show() on creation, making a new post-it. A button in the main class creates objects from this PostIt class and adds them to an ArrayList also in the Main class.

As the window is Undercoated I needed a way to drag the PostIt windows around and I found some code online. This code is commented with "***" in the PostIt class.

So the problem is it dose kind of work... but it mainly just glitches the window around the screen as you try to drag it to a new position. I have no I idea why this is happening...

Main Class:

package com.company;
 
import javafx.application.Application;
import javafx.event.ActionEvent;
import javafx.event.EventHandler;
import javafx.scene.control.ComboBox;
import javafx.stage.Stage;
import javafx.scene.control.Button;
import javafx.scene.layout.AnchorPane;
import javafx.scene.Scene;
 
import java.util.*;
 
public class Main extends Application{
 
    //Cpntains PostIt Objects used to create new note window
    ArrayList<PostIt> notes = new ArrayList<PostIt>();
 
    public static void main(String [] args){
        launch(args);
    }
 
    @Override
    public void start(Stage primaryStage) throws Exception {
 
        primaryStage.setTitle("Winodw Title!!!");
 
        //Button for creating new note and adding it to notes array
        Button b1 = new Button();
        b1.setText("New Note");
 
        //drop down box for selecting color of nate
        ComboBox comboBox = new ComboBox();
        comboBox.getItems().addAll(
                "Random",
                "Blue",
                "Green",
                "Purple",
                "Yellow"
        );
        comboBox.getSelectionModel().selectFirst();
 
        //Make new note logic
        b1.setOnAction(new EventHandler<ActionEvent>() {
            @Override public void handle(ActionEvent e) {
                //holds new note
                PostIt newpost = null;
 
                //note id
                int id = 0;
 
                //get color from combobox
                String color;
                color = (String) comboBox.getValue();
                //System.out.println(color);
 
                //checks notes array length to calculate ID of new note
                if (notes.size() != 0){
                    int temp = notes.size() - 1;
                    id = notes.get(temp).getId() + 1;
                }
 
                try {
                    newpost = new PostIt(primaryStage, id, color);
                } catch (Exception ex) {
                    ex.printStackTrace();
                }
 
                //add note to notes list
                notes.add(newpost);
            }
        });
 
        //layout and stage
        AnchorPane layout = new AnchorPane();
        layout.getChildren().add(b1);
        layout.getChildren().add(comboBox);
        AnchorPane.setTopAnchor(comboBox, 40.0);
 
        Scene scene = new Scene(layout, 300, 250);
        primaryStage.setScene(scene);
        primaryStage.show();
 
    }
 
 
 
}

PostIt Class:

package com.company;
 
import javafx.application.Application;
import javafx.event.EventHandler;
import javafx.scene.Scene;
import javafx.scene.control.TextArea;
import javafx.scene.input.MouseEvent;
import javafx.scene.layout.AnchorPane;
import javafx.scene.layout.HBox;
import javafx.scene.paint.Color;
import javafx.scene.text.Font;
import javafx.stage.Stage;
import javafx.stage.StageStyle;
 
import java.util.Random;
 
 
public class PostIt extends Application {
    //post-it stage
    Stage stage;
    //ID
    int id;
 
    //used for drag window logic
    Double xOffset = 0.00;
    Double yOffset = 0.00;
 
    //color logic veriables
    String color;
    String hexcolor1;
    String hexcolor2;
 
    public PostIt(Stage primaryStage, int id, String color) throws Exception {
        //set ID and color
        this.id = id;
        this.color = color;
 
        //if color is random - roll and set new color
        if (this.color.equals("Random")){
            int rand = getRandomNumberInRange(1,4);
            System.out.println(rand);
            if (rand == 1) this.color = "Blue";
            else if (rand == 2) this.color = "Green";
            else if (rand == 3) this.color = "Purple";
            else if (rand == 4) this.color = "Yellow";
        }
 
        //set color values
        if (this.color.equals("Blue")){
            hexcolor1 = "#73ADEC";
            hexcolor2 = "#A0CCF9";
        }
        else if (this.color.equals("Green")){
            hexcolor1 = "#C6E951";
            hexcolor2 = "#DDF681";
        }
        else if (this.color.equals("Purple")){
            hexcolor1 = "#E86BCF";
            hexcolor2 = "#FA94E8";
        }
        else if (this.color.equals("Yellow")){
            hexcolor1 = "#F0CC40";
            hexcolor2 = "#FAE278";
        }
 
        //start stage
        stage = new Stage();
        stage.initOwner(primaryStage);
        start(stage);
 
    }
 
    @Override
    public void start(Stage stage) throws Exception {
        stage.initStyle(StageStyle.UNDECORATED);
 
        //fix stage size
        stage.setMaxHeight(400);
        stage.setMaxWidth(400);
        stage.setMinHeight(400);
        stage.setMinWidth(400);
 
        stage.setResizable(false);
 
        //create textbox and set color - hexcolor2
        TextArea textArea = new TextArea();
        textArea.setFont(Font.font("Comic Sans MS", 22));
        textArea.setWrapText(true);
        textArea.setStyle("-fx-focus-color: transparent; -fx-text-box-border: transparent;");
        textArea.setStyle("-fx-background-color: green");
        textArea.setStyle("-fx-control-inner-background:" + hexcolor2 + ";");
 
        //Set layout and color - hexcolor1
        AnchorPane pane = new AnchorPane(textArea);
        pane.styleProperty().set("-fx-background-color: " + hexcolor1);
 
        //set textArea location
        AnchorPane.setTopAnchor(textArea, 80.0);
        AnchorPane.setLeftAnchor(textArea, 0.0);
 
 
        //*****************Code for dragging window*****************
        pane.setOnMousePressed(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                    xOffset = stage.getX() - event.getSceneX();
                    yOffset = stage.getY() - event.getScreenY();
 
            }
        });
 
        pane.setOnMouseDragged(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
 
                    stage.setX(event.getSceneX() - xOffset);
                    stage.setY(event.getSceneY() - yOffset);
 
            }
        });
        //*****************End of code for Dragging window*****************
 
        Scene scene = new Scene(pane, 400, 400, Color.BLACK);
 
        stage.setScene(scene);
        stage.show();
        //System.out.println("" + getId());
    }
 
    public int getId() {
        return id;
    }
 
    public void setId(int id) {
        this.id = id;
    }
 
    private static int getRandomNumberInRange(int min, int max) {
 
        if (min >= max) {
            throw new IllegalArgumentException("max must be greater than min");
        }
 
        Random r = new Random();
        return r.nextInt((max - min) + 1) + min;
    }
}

--- Update ---

Fixed it. I was using getSceanX/Y and not getScreenX/Y. Also there was a small mistake in the math.

pane.setOnMousePressed(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
                    xOffset = event.getScreenX() - stage.getX();
                    yOffset = event.getScreenY() - stage.getY();
 
                    System.out.println(xOffset);
                    System.out.println(yOffset);
 
            }
        });
 
        pane.setOnMouseDragged(new EventHandler<MouseEvent>() {
            @Override
            public void handle(MouseEvent event) {
 
                    stage.setX(event.getScreenX() - xOffset);
                    stage.setY(event.getScreenY() - yOffset);
 
            }
        });