Flutter manage dx of Offset by swiping to right or left - flutter

Question

in Flutter application i want to divide width of screen to 10 part and when user swipe to right or left i could detect each part of this swipe, for example
after divide screen to 10 part i have a variable named screenParts as double which that has 0.0 by default, when user swipe to right the variable value should be plus 1 part and swipe to left should be minus the variable value minus
this variable value should be between 0.0 and 1, you could consider Tween<double>
double screenParts = 0.0;
final double screenWidth = MediaQuery.of(context).size.width / 10;
i want to use this value inside into this part of code:
return GestureDetector(
onPanUpdate: (details) {
if (details.delta.dx > 0) {
if (screenParts / screenWidth == 0) screenParts = screenParts += 0.1;
} else if (details.delta.dx < 0) {
if (screenParts / screenWidth == 0) screenParts = screenParts -= 0.1;
}
setState(() {});
},
child: SafeArea(
child: FadeTransition(
opacity: CurvedAnimation(parent: animation, curve: Curves.fastLinearToSlowEaseIn),
child: SlideTransition(
position: Tween<Offset>(
begin: animateDirection,
end: Offset(screenParts, 0), //<---- this part
).animate(CurvedAnimation(
parent: animation,
curve: Curves.fastLinearToSlowEaseIn,
)),
// ignore: void_checks
child: Material(elevation: 8.0, child: child)),
),
),
);
it means i try to manage dx of Offset by screenParts value with swiping to right or left

Answer 1

is this what you are looking for?
import 'package:flutter/material.dart';
void main() => runApp(MyApp());
class MyApp extends StatelessWidget {
#override
Widget build(BuildContext context) {
return MaterialApp(
title: 'Flutter Demo',
theme: ThemeData(
primarySwatch: Colors.blue,
),
home: Scaffold(
body: SafeArea(
child: MyHomePage(),
),
),
);
}
}
class MyHomePage extends StatefulWidget {
#override
_MyHomePageState createState() => _MyHomePageState();
}
class _MyHomePageState extends State<MyHomePage>
with SingleTickerProviderStateMixin {
double position = 0.0;
#override
void initState() {
super.initState();
}
void handleXChange(double deltaX) {
setState(() {
position = deltaX / MediaQuery.of(context).size.width;
});
}
#override
Widget build(BuildContext context) {
return Stack(
children: <Widget>[
Text(position.toString()),
DragArea(
handleXChange: handleXChange,
),
],
);
}
}
class DragArea extends StatefulWidget {
const DragArea({Key key, #required this.handleXChange}) : super(key: key);
final void Function(double newX) handleXChange;
#override
_DragAreaState createState() => _DragAreaState();
}
class _DragAreaState extends State<DragArea> {
double initX;
void onPanStart(DragStartDetails details) {
initX = details.globalPosition.dx;
}
void onPanUpdate(DragUpdateDetails details) {
var x = details.globalPosition.dx;
var deltaX = x - initX;
widget.handleXChange(deltaX);
}
#override
Widget build(BuildContext context) {
return GestureDetector(
onPanStart: onPanStart,
onPanUpdate: onPanUpdate,
child: Container(
decoration: BoxDecoration(
border: Border.all(
color: Colors.blueAccent,
),
),
),
);
}
}