JavaFX - limitando o alcance do mouse na janela e detectando colisão

Utilizamos uma rotina de código capaz de limitar
o alcance do mouse dentro da janela,
impedindo assim que os objetos mergulhe
desaparecendo do scene.

Veja abaixo uma imagem do programa em execução: 

Veja abaixo um vídeo com o programa funcionando:

Veja abaixo o código do programa:

import javafx.application.Application;

import javafx.event.EventHandler;

import javafx.scene.*;

import javafx.scene.canvas.Canvas;

import javafx.scene.canvas.GraphicsContext;

import javafx.scene.input.MouseEvent;

import javafx.scene.paint.Color;

import javafx.stage.Stage;

import java.util.ArrayList;

import javafx.scene.shape.*;

import javafx.scene.text.Font;

import javafx.scene.text.FontPosture;

import javafx.scene.text.FontWeight;

import javafx.scene.media.AudioClip;

public class PROJETO extends Application {

     Group root = new Group ( );

     Scene scene = new Scene ( root, 600, 300 );

     Canvas canvas = new Canvas ( 600, 300 );

     GraphicsContext ctx = canvas.getGraphicsContext2D ( );

     Circle circle_1 = new Circle ( 30 );

     Circle circle_2 = new Circle ( 30 );

     Circle circle_3 = new Circle ( 30 );

     double x = 0, y = 0;

     double k = 0;

     double w = 0;

     private ArrayList < Shape > nosObjct;

     String Audio = getClass ( ).getResource (

              "gun.wav" ).toString ( );

     AudioClip clip = new AudioClip ( Audio );

     // /////////////////////////////////////////////////////////////////////////

     public void Informe ( ) {

         ctx.setFont ( Font.font ( "Arial", FontWeight.BOLD, 13 ) );

         ctx.setFill ( Color.RED );

         ctx.fillText ( "Por: ", 200, 230 );

         ctx.setFill ( Color.BLUE );

         ctx.fillText ( "Samuel Lima", 240, 230 );

         ctx.setFill ( Color.BLACK );

         ctx.fillText ( "sa_sp10@hotmail.com", 200, 245 );

         ctx.setFill ( Color.RED );

         ctx.fillText ( " MUITO OBRIGADO", 250, 280 );

     }

     // /////////////////////////////////////////////////////////////////////////

     public void arrastaObjetos ( final Shape figuras ) {

         figuras.setOnMousePressed ( new EventHandler < MouseEvent > ( ) {

              @Override

              public void handle ( MouseEvent mouseEvent ) {        

                   x = figuras.getLayoutX ( ) - mouseEvent.getSceneX ( );

                   y = figuras.getLayoutY ( ) - mouseEvent.getSceneY ( );

                   figuras.setCursor ( Cursor.CROSSHAIR );

              }

         } );

         figuras.setOnMouseReleased ( new EventHandler < MouseEvent > ( ) {

              @Override

              public void handle ( MouseEvent mouseEvent ) {

                   figuras.setCursor ( Cursor.HAND );

              }

         } );

         figuras.setOnMouseDragged ( new EventHandler < MouseEvent > ( ) {

              @Override

              public void handle ( MouseEvent mouseEvent ) {

                   if ( mouseEvent.getSceneX ( ) > 50 &&

                            mouseEvent.getSceneX ( ) < 550 ) {

                        figuras.setLayoutX ( mouseEvent.getSceneX ( ) + x );

                   }

                   if ( mouseEvent.getSceneY ( ) > 50 &&

                            mouseEvent.getSceneY ( ) < 250 ) {

                        figuras.setLayoutY ( mouseEvent.getSceneY ( ) + y );                

                   }

                   if ( mouseEvent.getSceneX ( ) == 50 ||

                            mouseEvent.getSceneX ( ) == 550 ) {

                   }

                   if ( mouseEvent.getSceneY ( ) == 50 ||

                            mouseEvent.getSceneY ( ) == 250 ) {     

                   }

                   examineColisao ( figuras );

              }

         } );

     }

     // /////////////////////////////////////////////////////////////////////////

     private void examineColisao ( Shape figuras) {

         boolean colisao = false;

         for ( Shape blocoEstatico : nosObjct ) {

              if ( blocoEstatico  != figuras ) {

                   Shape intersect = Shape.intersect ( figuras, blocoEstatico  );

                   if ( intersect.getBoundsInLocal ( ).getWidth ( ) != -1 ) {        

                        colisao = true;

                   }

              }

         }

         if ( colisao ) {

              clip.play ( );

              figuras.setFill ( Color.RED );

         }           

         if ( !colisao ) {

              clip.stop ( );

              figuras.setFill ( Color.LIGHTCORAL );

         }

     }

     // /////////////////////////////////////////////////////////////////////////

     public int listaFiguras ( ) {

         nosObjct = new ArrayList < > ( );       

         circle_1.setCenterX ( 300.0 );

         circle_1.setCenterY ( 125.0 );

         circle_1.setRadius ( 30.0 );

         circle_1.setFill ( Color.LIGHTCORAL  );

         circle_2.setCenterX ( 130.0 );

         circle_2.setCenterY ( 225.0 );

         circle_2.setRadius ( 30.0 );

         circle_2.setFill ( Color.LIGHTCORAL  );

         circle_3.setCenterX ( 470.0 );

         circle_3.setCenterY ( 225.0 );

         circle_3.setRadius ( 30.0 );

         circle_3.setFill ( Color.LIGHTCORAL  );

         nosObjct.add ( circle_1 );

         nosObjct.add ( circle_2 );

         nosObjct.add ( circle_3 );

         for ( Shape moveFiguras : nosObjct ) {

              arrastaObjetos ( moveFiguras );

         }

         examineColisao ( nosObjct.get ( nosObjct.size ( ) - 1 ) );

         return 0;

     }

     // /////////////////////////////////////////////////////////////////////////

     @Override

     public void start ( Stage stage ) {

         stage.setTitle ( "JAVAFX - LIMITANDO O ALCANCE DO MOUSE NA"

                   + " JANELA E DETECTANDO COLISÃO" );

         ctx.setStroke ( Color.BLACK );

         ctx.setLineWidth ( 10.0 );

         ctx.strokeRoundRect ( 5, 5, 590, 290, 5, 5 );

         ctx.setFont ( Font.font ( "Helvetica", FontWeight.BOLD,

                   FontPosture.ITALIC, 20 ) );

         ctx.setFill ( Color.RED );

         ctx.fillText ( "JAVAFX - LIMITANDO O ALCANCE DO MOUSE\n\t"

                   + "NA JANELA E DETECTANDO COLISÃO", 90, 40 );

         listaFiguras ( );

         Informe ( );

         root.getChildren ( ).addAll ( canvas, circle_1, circle_2, circle_3 );

         stage.setScene ( scene );

         stage.show ( );

     }

     // /////////////////////////////////////////////////////////////////////////

     public static void main ( String [ ] args ) {

         launch ( args );

     }

}