samples/web/charts/example/lib/axes/numeric_initial_viewport.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 setting an initial viewport for ordinal axis.
///
/// This allows for specifying the specific range of data to show that differs
/// from what was provided in the series list.
///
/// In this example, the series list has numeric data from 0 to 10, but we
/// want to show from 3 to 7.
/// We can do this by specifying an [NumericExtents] in [NumericAxisSpec].

// EXCLUDE_FROM_GALLERY_DOCS_START
import 'dart:math';
// EXCLUDE_FROM_GALLERY_DOCS_END
import 'package:charts_flutter/flutter.dart' as charts;
import 'package:flutter_web/material.dart';

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

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

  /// Creates a [LineChart] with sample data and no transition.
  factory NumericInitialViewport.withSampleData() {
    return new NumericInitialViewport(
      _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 NumericInitialViewport.withRandomData() {
    return new NumericInitialViewport(_createRandomData());
  }

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

    final data = [
      new LinearSales(0, random.nextInt(100)),
      new LinearSales(1, random.nextInt(100)),
      new LinearSales(2, random.nextInt(100)),
      new LinearSales(3, random.nextInt(100)),
      new LinearSales(4, random.nextInt(100)),
      new LinearSales(5, random.nextInt(100)),
      new LinearSales(6, random.nextInt(100)),
      new LinearSales(7, random.nextInt(100)),
      new LinearSales(8, random.nextInt(100)),
      new LinearSales(9, random.nextInt(100)),
      new LinearSales(10, random.nextInt(100)),
    ];

    return [
      new charts.Series<LinearSales, int>(
        id: 'Sales',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (LinearSales sales, _) => sales.year,
        measureFn: (LinearSales sales, _) => sales.sales,
        data: data,
      )
    ];
  }
  // EXCLUDE_FROM_GALLERY_DOCS_END

  @override
  Widget build(BuildContext context) {
    return new charts.LineChart(
      seriesList,
      animate: animate,
      domainAxis: new charts.NumericAxisSpec(
          // Set the initial viewport by providing a new AxisSpec with the
          // desired viewport, in NumericExtents.
          viewport: new charts.NumericExtents(3.0, 7.0)),
      // Optionally add a pan or pan and zoom behavior.
      // If pan/zoom is not added, the viewport specified remains the viewport.
      behaviors: [new charts.PanAndZoomBehavior()],
    );
  }

  /// Create one series with sample hard coded data.
  static List<charts.Series<LinearSales, int>> _createSampleData() {
    final data = [
      new LinearSales(0, 5),
      new LinearSales(1, 25),
      new LinearSales(2, 100),
      new LinearSales(3, 75),
      new LinearSales(4, 55),
      new LinearSales(5, 66),
      new LinearSales(6, 110),
      new LinearSales(7, 70),
      new LinearSales(8, 20),
      new LinearSales(9, 25),
      new LinearSales(10, 45),
    ];

    return [
      new charts.Series<LinearSales, int>(
        id: 'Sales',
        colorFn: (_, __) => charts.MaterialPalette.blue.shadeDefault,
        domainFn: (LinearSales sales, _) => sales.year,
        measureFn: (LinearSales sales, _) => sales.sales,
        data: data,
      )
    ];
  }
}

/// Sample linear data type.
class LinearSales {
  final int year;
  final int sales;

  LinearSales(this.year, this.sales);
}