sliver_bar_chart 0.0.1

A package that supports Bar Chart in a Flutter Sliver. This Package allow us to add Bar Chart in Sliver and its set a Bar Chart as a Header on Slivers Scroll.

example/lib/main.dart

import 'dart:math' as math;

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

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

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

  @override
  Widget build(BuildContext context) {
    return const MaterialApp(
      home: MyHomePage(),
      debugShowCheckedModeBanner: false,
    );
  }
}

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

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

class _MyHomePageState extends State<MyHomePage> with TickerProviderStateMixin {
  final ScrollController _scrollController = ScrollController();
  late final List<BarChartData> _barValues;

  final double _minHeight = AppBar().preferredSize.height;
  final double _xAxisTextRotationAngle = 180.0;
  final int _yAxisIntervalCount = 8;
  double _maxHeight = 500.0;
  double _maxWidth = 10.0;

  final bool _restrain = true;
  final bool _fluctuating = false;
  bool _isScrolling = true;

  final int _sliverListChildCount = 20;

  @override
  void initState() {
    super.initState();
    _setupBarChartValues();

    _scrollController.addListener(() {
      setState(() {
        if (_scrollController.offset.roundToDouble() < 100.0) {
          _maxHeight = 500.0;
          _maxWidth = 10.0;
          _isScrolling = true;
        } else {
          if (_scrollController.offset.roundToDouble() >= 400.0) {
            _maxWidth = _scrollController.offset - 10;
          }
          _isScrolling = false;
        }
      });
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: SafeArea(
        child: CustomScrollView(
          controller: _scrollController,
          slivers: [
            SliverBarChart(
              restrain: _restrain,
              fluctuating: _fluctuating,
              minHeight: _minHeight,
              maxHeight: _maxHeight,
              maxWidth: _maxWidth,
              barWidget: BarChartWidget(
                maxHeight: _maxHeight,
                minHeight: _minHeight,
                barValues: _barValues,
                isScrolling: _isScrolling,
                yAxisIntervalCount: _yAxisIntervalCount,
                xAxisTextRotationAngle: _xAxisTextRotationAngle,
              ),
            ),
            SliverList(
              delegate: SliverChildBuilderDelegate(
                (BuildContext _, int index) => Container(
                  color: index.isOdd ? Colors.white : Colors.black12,
                  child: Center(
                    child: Padding(
                      padding: const EdgeInsets.all(8.0),
                      child: Text(
                        '$index',
                        textScaleFactor: 3.0,
                      ),
                    ),
                  ),
                ),
                childCount: _sliverListChildCount,
              ),
            ),
          ],
        ),
      ),
      resizeToAvoidBottomInset: false,
    );
  }

  void _setupBarChartValues() {
    _barValues = [
      BarChartData(
        x: '2014',
        y: 500.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2015',
        y: 800.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2016',
        y: 600.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2017',
        y: 900.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2018',
        y: 1000.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2019',
        y: 700.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2020',
        y: 500.0,
        barColor: _getRandomColor(),
      ),
      BarChartData(
        x: '2021',
        y: 300.0,
        barColor: _getRandomColor(),
      ),
    ];
  }

  Color _getRandomColor() {
    return Color(
      (math.Random().nextDouble() * 0xFFFFFF).toInt(),
    ).withOpacity(1.0);
  }
}