Javafx retrievable drag and drop bug - javafx

Question

I am creating a javafx application with a drag and drop feature. I need to be able to drag from one pane and drop to the next pane. After dropping, all dropped nodes need to be accessible. The drag and drop is working smoothly. However, I am having a problem in which not all nodes are accessible after being dropped. I would drag a node and click on it and sometimes it would respond, but sometimes a random node would no longer exhibit capabilities when I clicked on it. There was no noticeable pattern (that I could see) about which nodes stopped working and which always worked. If anyone has any idea as to why this might be a problem or how to fix it, it would be greatly appreciated. I have looked everywhere and found only one similar issue a few years ago but the page with their solution had been removed.
I will briefly explain how I set up my code structure.
The nodes I am dragging extend StackPane and I drag these nodes onto a center Pane from an ImageView in VBox. However, both of these are children of a Main layout that extends BorderPane which I have called MainEntrance.
In my node's class I have onMousePressed and onMouseDragged features as well as onContextMenuRequested features. In the class of the MainEntrance, I have drag features, as well, that handle when an object is first dragged onto the child Pane from the other child VBox.
The following are the relevant classes/methods:
VBox class: (where nodes are dragged from)
ImageView iV= new ImageView(image);
iV.setId("image");
iV.setOnDragDetected(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
dragAndDrop(iV, iV.getId(), event);
}
});
I have drag three ImageViews and these ImageViews are children of a VBox.
MainEntrance:
In this class I have a method that registers my drag events to my pane as such:
PView is my class extension of Pane
public void registerOnDragDropped(PView pView){
pView.setOnDragOver(new EventHandler<DragEvent>() {
#Override
public void handle(DragEvent event) {
event.acceptTransferModes(TransferMode.ANY);
System.out.println("drag over registered");
}
});
pView.setOnDragDropped(new EventHandler<DragEvent>() {
#Override
public void handle(DragEvent event) {
Dragboard db = event.getDragboard();
final String id = db.getString();
double mousePosY = event.getY();
double mousePosX = event.getX();
deviceCounter += 1;
pView.createBoardView(id, deviceCounter, mousePosX, mousePosY);
event.setDropCompleted(true);
}
});
pView.setOnDragExited(new EventHandler<DragEvent>() {
#Override
public void handle(DragEvent event) {
event.acceptTransferModes(TransferMode.ANY);
//computerView.setEffect(null);
event.consume();
}
});
}
Note: this method is in my MainEntrance class (BorderPane). In this class is when I initialize all other child nodes of MainEntrance.
Node: (draggable nodes extend StackPane)
my node's handlers are in a method that I called makeDraggable()
public void makeDraggable(Node node) {
this.setOnMousePressed(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
node.getScene().setCursor(Cursor.MOVE);
System.out.println("makeDraggable mouse pressed");
}
});
node.setOnMouseReleased(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
node.getScene().setCursor(Cursor.DEFAULT);
}
});
node.setOnMouseDragged(new EventHandler<MouseEvent>() {
#Override
public void handle(MouseEvent event) {
node.setTranslateX(node.getTranslateX() + event.getX() - 35);
node.setTranslateY(node.getTranslateY() + event.getY() - 35);
event.consume();
node.toFront();
}
});
}
If any other information is needed please let me know. Thank you in advance!

Answer 1

I have figured out the solution to this problem.
The problem was in the rendering order of an attachment I had placed on the node. So when I drag the node on to the screen, I have another node (a line placed on a Pane) that binds the center of the screen to the node. I did not initially think that this was the problem, so I did not even include that class or snippet. However, after playing around with it I realized that this indeed was the problem. I had to add the line to the top of the rendering order. This can be done in the following way in whatever method allows you to create a new node:
Pane line = new Pane();
//add whatever code binds your line to desired places
getChildren.add(0, line);
//add the other node as child