Can't pass the flutter slider value to int

user_13196134 0
Viewed 46

inital value of _value is 200, but when i change the value with the slider, it does not pass it to the controller (i mean because of init it takes as default 200 and never changes)

  int _value = 200;

  @override
  void initState() {
    super.initState();
    _yellowController = AnimationController(
        duration: Duration(milliseconds: _value), vsync: this)
      ..addListener(() {
        setState(() {});
      });
  }

Slider(
                min: 200,
                max: 2000,
                activeColor: Colors.black54,
                inactiveColor: Colors.black12,
                thumbColor: Colors.black,
                value: _value.toDouble(),
                onChanged: (value) {
                  _value = value.round();
                  setState(() {});
                },
              ),
dart flutter
2 Answers

You need to delete setState(() {}); into addListener code. Because it's doing automatically. If you do setState in addListener code it's rebuild again and returns to starting position

user_153982020

You can see this StackOverflow answer that you can just change the _yellowController.duration and animate foward/reverse/repeat again. Try this code on https://dartpad.dev/ :

import 'package:flutter/material.dart';

const Color darkBlue = Color.fromARGB(255, 18, 32, 47);

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      theme: ThemeData.dark().copyWith(
        scaffoldBackgroundColor: darkBlue,
      ),
      debugShowCheckedModeBanner: false,
      home: const MyWidget(),
    );
  }
}

class MyWidget extends StatefulWidget {
  const MyWidget({super.key});

  @override
  createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget>
    with SingleTickerProviderStateMixin {
  int _value = 200;
  late AnimationController _yellowController;
  late Animation<double> animation;

  @override
  void initState() {
    super.initState();
    _yellowController = AnimationController(
      duration: Duration(milliseconds: _value),
      vsync: this,
    );
    _yellowController.repeat(reverse: true);
    animation = Tween<double>(begin: 0, end: 1).animate(_yellowController);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: const Text('AppBar Title'),
      ),
      body: Center(
        child: Column(
          mainAxisSize: MainAxisSize.min,
          children: [
            AnimatedBuilder(
              animation: animation,
              builder: (context, child) {
                return Transform.scale(
                  scale: animation.value,
                  child: child!,
                );
              },
              child: const SizedBox.square(
                dimension: 50,
                child: ColoredBox(
                  color: Colors.white,
                ),
              ),
            ),
            Slider(
              min: 200,
              max: 2000,
              activeColor: Colors.black54,
              inactiveColor: Colors.black12,
              thumbColor: Colors.black,
              value: _value.toDouble(),
              onChanged: (value) {
                _yellowController.duration = Duration(milliseconds: value.round());
                _yellowController.repeat(reverse: true);
                _value = value.round();
                setState(() {});
              },
            ),
          ],
        ),
      ),
    );
  }
}
user_95768700
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