flutter charts datetime graph generalizing dates too much

I'm using a flutter chart in my project (https://google.github.io/charts/flutter/example/time_series_charts/simple.html), in my database I have very precise times, however the package is dumbing it down and generalizing the dates more then I would like. There are two options I can think of, both of which I can't figure out how to do. 1: either set the package to print more accurate times or 2: hide or delete the x-axis labels so I can generate my own. Any help would be appreciated, thx

My app

1 answer

  • answered 2019-11-14 04:11 chunhunghan

    Use domainAxis attribute and set TimeFormatterSpec
    the following picture show effect of transitionFormat: 'dd MM' and transitionFormat: 'dd MMM' You can copy paste run full code below

    code snippet

    @override
      Widget build(BuildContext context) {
        return new charts.TimeSeriesChart(
          seriesList,
          animate: animate,
          // Optionally pass in a [DateTimeFactory] used by the chart. The factory
          // should create the same type of [DateTime] as the data provided. If none
          // specified, the default creates local date time.
          dateTimeFactory: const charts.LocalDateTimeFactory(),
          domainAxis: charts.DateTimeAxisSpec(
            tickFormatterSpec: charts.AutoDateTimeTickFormatterSpec(
              day: charts.TimeFormatterSpec(
                format: 'dd',
                transitionFormat: 'dd MMM',
              ),
            ),
          ),
        );
      }
    

    Demo dd MM and dd MMM

    enter image description here

    full code

    import 'package:charts_flutter/flutter.dart' as charts;
    import 'package:flutter/material.dart';
    
    class SimpleTimeSeriesChart extends StatelessWidget {
      final List<charts.Series> seriesList;
      final bool animate;
    
      SimpleTimeSeriesChart(this.seriesList, {this.animate});
    
      /// Creates a [TimeSeriesChart] with sample data and no transition.
      factory SimpleTimeSeriesChart.withSampleData() {
        return new SimpleTimeSeriesChart(
          _createSampleData(),
          // Disable animations for image tests.
          animate: false,
        );
      }
    
      @override
      Widget build(BuildContext context) {
        return new charts.TimeSeriesChart(
          seriesList,
          animate: animate,
          // Optionally pass in a [DateTimeFactory] used by the chart. The factory
          // should create the same type of [DateTime] as the data provided. If none
          // specified, the default creates local date time.
          dateTimeFactory: const charts.LocalDateTimeFactory(),
          domainAxis: charts.DateTimeAxisSpec(
            tickFormatterSpec: charts.AutoDateTimeTickFormatterSpec(
              day: charts.TimeFormatterSpec(
                format: 'dd',
                transitionFormat: 'dd MMM',
              ),
            ),
          ),
        );
      }
    
      /// Create one series with sample hard coded data.
      static List<charts.Series<TimeSeriesSales, DateTime>> _createSampleData() {
        final data = [
          new TimeSeriesSales(new DateTime(2017, 9, 19), 5),
          new TimeSeriesSales(new DateTime(2017, 9, 26), 25),
          new TimeSeriesSales(new DateTime(2017, 10, 3), 100),
          new TimeSeriesSales(new DateTime(2017, 10, 10), 75),
        ];
    
        return [
          new charts.Series<TimeSeriesSales, DateTime>(
            id: 'Sales',
            colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
            domainFn: (TimeSeriesSales sales, _) => sales.time,
            measureFn: (TimeSeriesSales sales, _) => sales.sales,
            data: data,
          )
        ];
      }
    }
    
    /// Sample time series data type.
    class TimeSeriesSales {
      final DateTime time;
      final int sales;
    
      TimeSeriesSales(this.time, this.sales);
    }
    
    void main() => runApp(MyApp());
    
    class MyApp extends StatelessWidget {
      // This widget is the root of your application.
      @override
      Widget build(BuildContext context) {
        return MaterialApp(
          title: 'Flutter Demo',
          theme: ThemeData(
            // This is the theme of your application.
            //
            // Try running your application with "flutter run". You'll see the
            // application has a blue toolbar. Then, without quitting the app, try
            // changing the primarySwatch below to Colors.green and then invoke
            // "hot reload" (press "r" in the console where you ran "flutter run",
            // or simply save your changes to "hot reload" in a Flutter IDE).
            // Notice that the counter didn't reset back to zero; the application
            // is not restarted.
            primarySwatch: Colors.blue,
          ),
          home: MyHomePage(title: 'Flutter Demo Home Page'),
        );
      }
    }
    
    class MyHomePage extends StatefulWidget {
      MyHomePage({Key key, this.title}) : super(key: key);
    
      // This widget is the home page of your application. It is stateful, meaning
      // that it has a State object (defined below) that contains fields that affect
      // how it looks.
    
      // This class is the configuration for the state. It holds the values (in this
      // case the title) provided by the parent (in this case the App widget) and
      // used by the build method of the State. Fields in a Widget subclass are
      // always marked "final".
    
      final String title;
    
      @override
      _MyHomePageState createState() => _MyHomePageState();
    }
    
    class _MyHomePageState extends State<MyHomePage> {
      int _counter = 0;
    
      void _incrementCounter() {
        setState(() {
          // This call to setState tells the Flutter framework that something has
          // changed in this State, which causes it to rerun the build method below
          // so that the display can reflect the updated values. If we changed
          // _counter without calling setState(), then the build method would not be
          // called again, and so nothing would appear to happen.
          _counter++;
        });
      }
    
      @override
      Widget build(BuildContext context) {
        // This method is rerun every time setState is called, for instance as done
        // by the _incrementCounter method above.
        //
        // The Flutter framework has been optimized to make rerunning build methods
        // fast, so that you can just rebuild anything that needs updating rather
        // than having to individually change instances of widgets.
        return Scaffold(
          appBar: AppBar(
            // Here we take the value from the MyHomePage object that was created by
            // the App.build method, and use it to set our appbar title.
            title: Text(widget.title),
          ),
          body: Center(
            // Center is a layout widget. It takes a single child and positions it
            // in the middle of the parent.
            child: Column(
              // Column is also a layout widget. It takes a list of children and
              // arranges them vertically. By default, it sizes itself to fit its
              // children horizontally, and tries to be as tall as its parent.
              //
              // Invoke "debug painting" (press "p" in the console, choose the
              // "Toggle Debug Paint" action from the Flutter Inspector in Android
              // Studio, or the "Toggle Debug Paint" command in Visual Studio Code)
              // to see the wireframe for each widget.
              //
              // Column has various properties to control how it sizes itself and
              // how it positions its children. Here we use mainAxisAlignment to
              // center the children vertically; the main axis here is the vertical
              // axis because Columns are vertical (the cross axis would be
              // horizontal).
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Expanded(flex: 5, child: SimpleTimeSeriesChart.withSampleData()),
                Text(
                  'You have pushed the button this many times:',
                ),
                Text(
                  '$_counter',
                  style: Theme.of(context).textTheme.display1,
                ),
              ],
            ),
          ),
          floatingActionButton: FloatingActionButton(
            onPressed: _incrementCounter,
            tooltip: 'Increment',
            child: Icon(Icons.add),
          ), // This trailing comma makes auto-formatting nicer for build methods.
        );
      }
    }