customstep flutter slider

customstep_sliderrange.dart

import 'package:flutter/material.dart';
import 'dart:math';

void main() => runApp(const MyApp());

class MyApp extends StatelessWidget {
  const MyApp({Key? key}) : super(key: key);

  static const String _title = 'Flutter Code CustomStep_RangeSlider';

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: _title,
      home: Scaffold(
        appBar: AppBar(title: const Text(_title)),
        body: const Custom_RangeSliderWidget(),
      ),
    );
  }
}




class Custom_RangeSliderWidget extends StatefulWidget {
  const Custom_RangeSliderWidget({Key? key}) : super(key: key);

  @override
  State<Custom_RangeSliderWidget> createState() => _Custom_RangeSliderWidgetState();
}

class _Custom_RangeSliderWidgetState extends State<Custom_RangeSliderWidget> {
  //This fella actually holds Indexes notValues. 
  RangeValues _currentRangeValues = const RangeValues(0, 49);
 
  //edit: Use this funcs to getGbvalues from slider min max handle
  double GetSliderMinValue(){
    var tmp= getGbFromRangeValue(_currentRangeValues.start.round()); 
    return tmp;
  }

  double GetSliderMaxValue(){
    var tmp = getGbFromRangeValue(_currentRangeValues.end.round()) ;
    return tmp;
  }


  List<double> generateList(double min,double max,double stepSize) 
  {
    //List<double>.generate(7, (i) => i * 0.05)
     List<double> tmplist = [];
     var stepCount = (max -min)/stepSize;
    
     for( var i = 0 ; i < stepCount ; i++ ) { 
      tmplist.add(min+ i*stepSize);
   } 
    return tmplist ;
  }
  List<double> gblist = [];
  List<double> generateGbArray() {
    return 
      generateList(0.0  ,0.30 ,0.05)+
      generateList(0.3  ,1    ,0.1)+
      generateList( 1   ,5    ,0.5)+
      generateList( 5   ,10   ,1)+
      generateList( 10  ,50   ,5)+
      generateList( 50  ,100  ,10)+
      generateList( 100 ,1000 ,100) 
      + [1000 ]  /*1terabyte */
      +[1000 * 1024 ] /*1000terabyte , u cant even download this*/
      
      ;
  }

  double getGbFromRangeValue(int rangeValue) {
    if (gblist.isEmpty) {
      gblist = generateGbArray();
    }
    //return -1;
    
    if(rangeValue>=gblist.length)
      return -2;//index out of bounds

    var retval = gblist.elementAt(rangeValue);

    return retval;
  }

  @override
  Widget build(BuildContext context) {
    
    //this func inits "gblist" ifEmpty
    var dump= getGbFromRangeValue(1);
   
    var listLength = 49; 
    // Dont have to  write 49 anymore
    listLength = gblist.length;

    return RangeSlider(
      values: _currentRangeValues,
      max: listLength,
      divisions: listLength,
      labels: RangeLabels(
        GetSliderMinValue()
                .toStringAsFixed(2) + "gb",
        GetSliderMaxValue()
                .toStringAsFixed(2) + "gb",
      ),
      onChanged: (RangeValues values) {
        setState(() {
          _currentRangeValues = values;
           
          //Debug-start-
          //_currentRangeValues is holding Indexes
          // Word "Value is misguiding, i know"
          
          //Get Indexes 1 to 49
          print(_currentRangeValues);

          //GetValues 0 to 1000terabyte
          var min =GetSliderMinValue();
          print(min);
          var max =GetSliderMaxValue();
          print(max);
          //Debug-end-

        });
      },
    );
  }
}