Updating a widget from a List<Widget> in flutter? - flutter

Question

I need to know of there is any possible way to update the properties of a widget like size and colour after it is added to a List.. consider the following code..
List<Widget> tree = [];
And I'm adding the following widget when it is Dragged and dropped on the container.. To show multiple widgets i'm using a stack..
DragTarget and Stack are as follows...
DragTarget<String>(
builder: (a,b,c)=>Stack(
children: tree,
),
onAccept: (data){
tree.add(Positioned(
key: Key("$sx$sy"),
top: _y,
left: _x,
child: FlatButton(
onPressed: (){
},
child: CustomPaint(
size: Size(sx/2, sy/2),
painter: ShapePainter(shape: "circle", sx : sx/2, sy: sy/2),
child: Container(
width: sx,
height: sy,
),
),
),
)
);
}
From the Image.. I want to achieve that whenever I click a circle I should be able to update its shape and size by gestures..
NOTE
I achieved similar feature by creating a new Widget of same type and desired properties not by gestures but by filling the details in InputFields and then replacing it in following ways..
List<Widget> tree;
//Then replace it with..
tree.insert(0, Container());
OR
tree.insert(1, Container());
I don't need this to work..
I need to access the properties of the item on which I clicked and then update its shape and size with gestures.
Resource
If you need to see my complete code then use https://github.com/AbhijeetDash/designer
Feel free to contribute..

Answer 1

You need to create a custom stateful widget for your items and change the state whenever they are clicked.
class CustomItem extends StatefulWidget {
#override
_CustomItemState createState() => _CustomItemState();
}
class _CustomItemState extends State<CustomItem> {
var desiredChangingVariable;
#override
Widget build(BuildContext context) {
return Positioned(
key: Key("$sx$sy"),
top: _y,
left: _x,
child: FlatButton(
onPressed: (){
setState(() {
//desiredChangingVariable = newValue;
});
},
child: CustomPaint(
size: Size(sx/2, sy/2),
painter: ShapePainter(shape: "circle", sx : sx/2, sy: sy/2),
child: Container(
width: sx,
height: sy,
),
),
),
);
}
}
Additionally, make sure you won’t forget about keys when you’re dealing with populated stateful items.