Flutter Drag and Drop - flutter

Question

I'm facing a problem implementing drag and drop in my project. I want dynamically add and delete draggable elements. The problem is that I can't understand how to get the reference to the widget I'm currently moving so that I can understand which coordinates in the list I have to change.
Here is an example of the code where I use the static number of draggable widgets. They are assigned with coordinates from the list. But what if I have to dynamically add and delete those draggable widgets how can I understand which coordinates to change?
So, I have an array of draggble elements and array of coordinates. Widget with index 0 refers to coordinates with index 0. How can I understand which widget I'm currently moving so that I can get the index of it in array of widgets and then change proper coordinates in array of coordinates.
class DragAndDrop extends StatefulWidget {
const DragAndDrop({
Key? key,
this.width,
this.height,
}) : super(key: key);
final double? width;
final double? height;
#override
_DragAndDropState createState() => _DragAndDropState();
}
class _DragAndDropState extends State<DragAndDrop> {
List<double?> _x = [0.0, 20.0];
List<double?> _y = [0.0, 20.0];
int k = -1;
List<Widget> pel = [];
final GlobalKey stackKey = GlobalKey();
#override
Widget build(BuildContext context) {
pel.add(Container(color: Colors.blue));
k++;
Widget drag = Draggable<int>(
data: k,
child: Icon(
Icons.keyboard_arrow_down,
color: Color(0x95000000),
size: 40,
),
feedback: Icon(
Icons.keyboard_arrow_down,
color: Color.fromRGBO(212, 14, 14, 0.584),
size: 40,
),
childWhenDragging: Container(),
onDragStarted: () {},
onDragEnd: (dragDetails) {
setState(() {
final parentPos = stackKey.globalPaintBounds;
if (parentPos == null) return;
if (dragDetails.offset.dx - parentPos.left < 0)
_x[0] = 0;
else if (dragDetails.offset.dx - parentPos.left >
double.parse(widget.width.toString()) - 40)
_x[0] = double.parse(widget.width.toString()) - 40;
else
_x[0] = dragDetails.offset.dx - parentPos.left;
if (dragDetails.offset.dy - parentPos.top < 0)
_y[0] = 0;
else if (dragDetails.offset.dy - parentPos.top >
double.parse(widget.height.toString()) - 40)
_y[0] = double.parse(widget.height.toString()) - 40;
else
_y[0] = dragDetails.offset.dy - parentPos.top;
});
},
);
pel.add(Positioned(
left: _x[0],
top: _y[0],
child: drag,
));
pel.add(Positioned(
left: _x[1],
top: _y[1],
child: Draggable<int>(
data: k,
child: Icon(
Icons.keyboard_arrow_down,
color: Color(0x95000000),
size: 40,
),
feedback: Icon(
Icons.keyboard_arrow_down,
color: Color.fromRGBO(212, 14, 14, 0.584),
size: 40,
),
childWhenDragging: Container(),
onDragStarted: () {},
onDragEnd: (dragDetails) {
setState(() {
final parentPos = stackKey.globalPaintBounds;
if (parentPos == null) return;
_x[1] = dragDetails.offset.dx - parentPos.left; // 11.
_y[1] = dragDetails.offset.dy - parentPos.top;
});
},
),
));
return Stack(
key: stackKey,
fit: StackFit.expand,
children: pel,
);
}
}
extension GlobalKeyExtension on GlobalKey {
Rect? get globalPaintBounds {
final renderObject = currentContext?.findRenderObject();
var translation = renderObject?.getTransformTo(null).getTranslation();
if (translation != null && renderObject?.paintBounds != null) {
return renderObject!.paintBounds
.shift(Offset(translation.x, translation.y));
} else {
return null;
}
}
}
I tried to use a variable that I can assign to Dragble.data field but I'm not able to get it inside the widget.