samples/web/charts/lib/axes/integer_only_measure_axis.dart

// Copyright 2018 the Charts project authors. Please see the AUTHORS file
// for details.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

/// Example of timeseries chart forcing the measure axis to have whole number
/// ticks. This is useful if the measure units don't make sense to present as
/// fractional.
///
/// This is done by customizing the measure axis and setting
/// [dataIsInWholeNumbers] on the tick provider.
// EXCLUDE_FROM_GALLERY_DOCS_START
import 'dart:math';
// EXCLUDE_FROM_GALLERY_DOCS_END
import 'package:charts_flutter/flutter.dart' as charts;
import 'package:flutter/material.dart';

class IntegerOnlyMeasureAxis extends StatelessWidget {
  final List<charts.Series> seriesList;
  final bool animate;

  IntegerOnlyMeasureAxis(this.seriesList, {this.animate});

  /// Creates a [TimeSeriesChart] with sample data and no transition.
  factory IntegerOnlyMeasureAxis.withSampleData() {
    return new IntegerOnlyMeasureAxis(
      _createSampleData(),
      // Disable animations for image tests.
      animate: false,
    );
  }

  // EXCLUDE_FROM_GALLERY_DOCS_START
  // This section is excluded from being copied to the gallery.
  // It is used for creating random series data to demonstrate animation in
  // the example app only.
  factory IntegerOnlyMeasureAxis.withRandomData() {
    return new IntegerOnlyMeasureAxis(_createRandomData());
  }

  /// Create random data.
  static List<charts.Series<MyRow, DateTime>> _createRandomData() {
    final random = new Random();

    final data = [
      new MyRow(new DateTime(2017, 9, 25), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 9, 26), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 9, 27), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 9, 28), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 9, 29), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 9, 30), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 10, 01), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 10, 02), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 10, 03), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 10, 04), random.nextDouble().round()),
      new MyRow(new DateTime(2017, 10, 05), random.nextDouble().round()),
    ];

    return [
      new charts.Series<MyRow, DateTime>(
        id: 'Headcount',
        domainFn: (MyRow row, _) => row.timeStamp,
        measureFn: (MyRow row, _) => row.headcount,
        data: data,
      )
    ];
  }
  // EXCLUDE_FROM_GALLERY_DOCS_END

  @override
  Widget build(BuildContext context) {
    return new charts.TimeSeriesChart(
      seriesList,
      animate: animate,
      // Provides a custom axis ensuring that the ticks are in whole numbers.
      primaryMeasureAxis: new charts.NumericAxisSpec(
          tickProviderSpec: new charts.BasicNumericTickProviderSpec(
              // Make sure we don't have values less than 1 as ticks
              // (ie: counts).
              dataIsInWholeNumbers: true,
              // Fixed tick count to highlight the integer only behavior
              // generating ticks [0, 1, 2, 3, 4].
              desiredTickCount: 5)),
    );
  }

  /// Create one series with sample hard coded data.
  static List<charts.Series<MyRow, DateTime>> _createSampleData() {
    final data = [
      new MyRow(new DateTime(2017, 9, 25), 0),
      new MyRow(new DateTime(2017, 9, 26), 0),
      new MyRow(new DateTime(2017, 9, 27), 0),
      new MyRow(new DateTime(2017, 9, 28), 0),
      new MyRow(new DateTime(2017, 9, 29), 0),
      new MyRow(new DateTime(2017, 9, 30), 0),
      new MyRow(new DateTime(2017, 10, 01), 1),
      new MyRow(new DateTime(2017, 10, 02), 1),
      new MyRow(new DateTime(2017, 10, 03), 1),
      new MyRow(new DateTime(2017, 10, 04), 1),
      new MyRow(new DateTime(2017, 10, 05), 1),
    ];

    return [
      new charts.Series<MyRow, DateTime>(
        id: 'Headcount',
        domainFn: (MyRow row, _) => row.timeStamp,
        measureFn: (MyRow row, _) => row.headcount,
        data: data,
      )
    ];
  }
}

/// Sample time series data type.
class MyRow {
  final DateTime timeStamp;
  final int headcount;
  MyRow(this.timeStamp, this.headcount);
}