Flutter - Save Multiple Widget Transformation Before setState - flutter

Question

I have a Stack with multiple MatrixGesture Containers with images that can be drag around, pinch zoom and rotate. I want to save the state of each container in the position and shape that it is, because after a little change using setState, everything go back to the original position.
All the information of the images is in a List with a specific object type.
Here is a snippet of the code to display the images:
class NewOutfitState extends State<NewOutfit> {
List<DisplayGarment> garmentsList;
#override
Widget build(BuildContext context) {
return new Scaffold(
appBar: new AppBar(
title: new Text("New"),
body: new Container(
child:MyList(myList: garmentsList, canvasSize: realCanvas,);
)
}
}
class MyListState extends State<MyList>{
List<DisplayGarment> myList;
double realCanvas;
bool flag=false;
int touch=0;
#override
void initState() {
super.initState();
myList=widget.myList;
realCanvas = widget.canvasSize;
}
#override
Widget build(BuildContext context) {
return Stack(
children: getList(),
);
}
List<Widget> getList(){
List<Widget> listWidget=[];
for(int i=0;i<myList.length;i++) {
final ValueNotifier<Matrix4> notifier1= ValueNotifier(Matrix4.identity());
DisplayGarment _garments = myList[i];
listWidget.add(
MatrixGestureDetector(
key: Key(i.toString()),
onMatrixUpdate: (m, tm, sm, rm) {
notifier1.value = m;
},
child: AnimatedBuilder(
animation: notifier1,
builder: (ctx, child) {
return Transform(
transform: notifier1.value,
child: Stack(
children: <Widget>[
Container(
padding: EdgeInsets.all(4),
alignment: Alignment(0, -0.5),
child:
Container(
padding: EdgeInsets.all(0),
height: imgHeigh,
width: imgWidth,
child:
DottedBorder(
color: Colors.transparent,
strokeWidth: 0,
child: Center(
child: CachedNetworkImage(
imageUrl:
'https://fashiers.com/garments_img/'+imgUrl,
height: imgHeigh,
width: imgWidth,
)),
);
,)
)
],),);},),
)
);
}
return listWidget;
}
}
Also is it possible to set a border around the image when that is tap on and remove border on other that was probably tap before?
I appreciate any help with this.

Answer 1

For the first part, you should not put notifier1 initialization inside the build function. That's why every time you use setStatus, your position reset. This part should be initialize inside initState() and that means you should keep all garments location value in this class. (e.g. List<ValueNotifier>)
Second part, indexing the garments may be the instinctive solution. Display/Hide border by:
child: _selectedIndex == i ?
// Widget with border
: //Widget without border
and set _selectedIndex inside onMatrixUpdate()