JavaFX拖放到GridPane吗？

Question

I have implemented a drag-and-drop function to my game, but so far I can only "drop" to hard-coded locations. As shown here:

What I would like is for either:

1. When the ships is dropped its x,y values (in relation to the GridPane) are saved, or
2. The cell that the ship is dropped to is saved.

My setOnDragDropped event is handled here:

//Drag dropped draws the image to the receiving node
    target.setOnDragDropped(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //Data dropped
            //If there is an image on the dragboard, read it and use it
            Dragboard db = event.getDragboard();
            boolean success = false;
            int x, y;
            if(db.hasImage()){
                //target.setText(db.getImage()); --- must be changed to target.add(source, col, row)
                //target.add(source, 5, 5, 1, 1);
                //Places at 0,0 - will need to take coordinates once that is implemented
                Board.add(test, 0, 0, 1, 1);
                success = true;
            }
            //let the source know whether the image was successfully transferred and used
            event.setDropCompleted(success);

            event.consume();
        }
    });

I feel like this should be simple to do as a MouseOver event or something similar but I am not sure what to do.

Edit: Full code for class below:

public class Controller implements Initializable{
@FXML
public GridPane Board;
public GridPane ShipsToBePlaced;
public Rectangle MessageBox;
public Button ReadyButton;
public Button QuitButton;
public ImageView[][] water;
public ImageView[] ships;
public ImageView[][] ships2d;

@Override
public void initialize(URL location, ResourceBundle resources) {
    //Adds water to each cell in grid
    water = new ImageView[10][10];
    //ships2d = new ImageView[10][10];
    for(int i =0; i<10; i++){
        for(int j=0; j <10; j++){
            water[i][j] = new ImageView("Tiles/watertile.png");
            water[i][j].setPreserveRatio(true);
            water[i][j].setFitHeight(49);
            water[i][j].setFitWidth(49);
            Board.add(water[i][j], i, j);
            //ships2d[i][j] = new ImageView("Ships/ship2.png");
            //ships2d[i][j].setPreserveRatio(true);
            //ships2d[i][j].setFitWidth(49);
            //Board.add(ships2d[i][j], i, j);

        }
    }
    //Adds ships
    ships = new ImageView[5];
    ships[0] = new ImageView("Ships/ship2.png");
    ships[1] = new ImageView("Ships/ship3.png");
    ships[2] = new ImageView("Ships/ship3.png");
    ships[3] = new ImageView("Ships/ship4.png");
    ships[4] = new ImageView("Ships/ship5.png");
    for(int i=0; i < 5; i++){
        ships[i].setPreserveRatio(true);
    }
    ships[0].setFitWidth(80);
    ships[1].setFitWidth(120);
    ships[2].setFitWidth(120);
    ships[3].setFitWidth(160);
    ships[4].setFitWidth(200);
    //ShipsToBePlaced.add(ships[0], 0, 0);
    ShipsToBePlaced.add(ships[1], 0, 1);
    ShipsToBePlaced.add(ships[2], 0, 2);
    ShipsToBePlaced.add(ships[3], 0, 3);
    ShipsToBePlaced.add(ships[4], 0, 4);


    //Test imageview for dropped ship
    ImageView test = new ImageView("Ships/ship2.png");
    test.setPreserveRatio(true);
    test.setFitWidth(80);


    //First attempt at drag and drop
    ImageView source = new ImageView ("Ships/ship2.png");
    source.setPreserveRatio(true);
    source.setFitWidth(80);
    ShipsToBePlaced.add(source, 0, 0);
    final GridPane target = Board;

    //Drag detected event handler is used for adding drag functionality to the boat node
    source.setOnDragDetected(new EventHandler<MouseEvent>() {
        public void handle(MouseEvent event) {
            //Drag was detected, start drap-and-drop gesture
            //Allow any transfer node
            Dragboard db = source.startDragAndDrop(TransferMode.ANY);

            //Put ImageView on dragboard
            ClipboardContent cbContent = new ClipboardContent();
            cbContent.putImage(source.getImage());
            //cbContent.put(DataFormat.)
            db.setContent(cbContent);
            source.setVisible(false);
            event.consume();
        }
    });

    //Drag over event handler is used for the receiving node to allow movement
    target.setOnDragOver(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //data is dragged over to target
            //accept it only if it is not dragged from the same node
            //and if it has image data
            if(event.getGestureSource() != target && event.getDragboard().hasImage()){
                //allow for moving
                event.acceptTransferModes(TransferMode.MOVE);
            }
            event.consume();
        }
    });

    //Drag entered changes the appearance of the receiving node to indicate to the player that they can place there
    target.setOnDragEntered(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //The drag-and-drop gesture entered the target
            //show the user that it is an actual gesture target
            if(event.getGestureSource() != target && event.getDragboard().hasImage()){
                source.setVisible(false);
                target.setOpacity(0.7);
                System.out.println("Drag entered");
            }
            event.consume();
        }
    });

    //Drag exited reverts the appearance of the receiving node when the mouse is outside of the node
    target.setOnDragExited(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //mouse moved away, remove graphical cues
            source.setVisible(true);
            target.setOpacity(1);

            event.consume();
        }
    });

    //Drag dropped draws the image to the receiving node
    target.setOnDragDropped(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //Data dropped
            //If there is an image on the dragboard, read it and use it
            Dragboard db = event.getDragboard();
            boolean success = false;
            int x, y;
            if(db.hasImage()){
                //target.setText(db.getImage()); --- must be changed to target.add(source, col, row)
                //target.add(source, 5, 5, 1, 1);
                //Places at 0,0 - will need to take coordinates once that is implemented
                Board.add(test, 0, 0, 1, 1);
                success = true;
            }
            //let the source know whether the image was successfully transferred and used
            event.setDropCompleted(success);

            event.consume();
        }
    });

    source.setOnDragDone(new EventHandler<DragEvent>() {
        public void handle(DragEvent event) {
            //the drag and drop gesture has ended
            //if the data was successfully moved, clear it
            if(event.getTransferMode() == TransferMode.MOVE){
                source.setVisible(false);
            }
            event.consume();
        }
    });
}

}

Answer 1

If you get access to the Node where this was actually dropped, you can determine the indices in the GridPane and use the same indices for the new node and/or use the indices any other way you want...

In this case you can get the target ImageView using DragEvent.getPickResult().getIntersectedNode() or Event.getTarget :

public void handle(DragEvent event) {
    //Data dropped
    //If there is an image on the dragboard, read it and use it
    Dragboard db = event.getDragboard();
    boolean success = false;
    Node node = event.getPickResult().getIntersectedNode();
    if(node != target && db.hasImage()){

        Integer cIndex = GridPane.getColumnIndex(node);
        Integer rIndex = GridPane.getRowIndex(node);
        int x = cIndex == null ? 0 : cIndex;
        int y = rIndex == null ? 0 : rIndex;
        //target.setText(db.getImage()); --- must be changed to target.add(source, col, row)
        //target.add(source, 5, 5, 1, 1);
        //Places at 0,0 - will need to take coordinates once that is implemented
        ImageView image = new ImageView(db.getImage());

        // TODO: set image size; use correct column/row span
        Board.add(image, x, y, 1, 1);
        success = true;
    }
    //let the source know whether the image was successfully transferred and used
    event.setDropCompleted(success);

    event.consume();
}

Note: Since you use the drag events using the system clipboard, other applications may be the source or target of a drag gesture...