samples/web/charts/example/lib/legends/legend_custom_symbol.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.

/// Bar chart with custom symbol in legend example.
// EXCLUDE_FROM_GALLERY_DOCS_START
import 'dart:math';
// EXCLUDE_FROM_GALLERY_DOCS_END
import 'package:flutter_web/material.dart';
import 'package:charts_flutter/flutter.dart' as charts;

/// Example custom renderer that renders [IconData].
///
/// This is used to show that legend symbols can be assigned a custom symbol.
class IconRenderer extends charts.CustomSymbolRenderer {
  final IconData iconData;

  IconRenderer(this.iconData);

  @override
  Widget build(BuildContext context, {Size size, Color color, bool enabled}) {
    // Lighten the color if the symbol is not enabled
    // Example: If user has tapped on a Series deselecting it.
    if (!enabled) {
      color = color.withOpacity(0.26);
    }

    return new SizedBox.fromSize(
        size: size, child: new Icon(iconData, color: color, size: 12.0));
  }
}

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

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

  factory LegendWithCustomSymbol.withSampleData() {
    return new LegendWithCustomSymbol(
      _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 LegendWithCustomSymbol.withRandomData() {
    return new LegendWithCustomSymbol(_createRandomData());
  }

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

    final desktopSalesData = [
      new OrdinalSales('2014', random.nextInt(100)),
      new OrdinalSales('2015', random.nextInt(100)),
      new OrdinalSales('2016', random.nextInt(100)),
      new OrdinalSales('2017', random.nextInt(100)),
    ];

    final tabletSalesData = [
      new OrdinalSales('2014', random.nextInt(100)),
      new OrdinalSales('2015', random.nextInt(100)),
      new OrdinalSales('2016', random.nextInt(100)),
      new OrdinalSales('2017', random.nextInt(100)),
    ];

    final mobileSalesData = [
      new OrdinalSales('2014', random.nextInt(100)),
      new OrdinalSales('2015', random.nextInt(100)),
      new OrdinalSales('2016', random.nextInt(100)),
      new OrdinalSales('2017', random.nextInt(100)),
    ];

    final otherSalesData = [
      new OrdinalSales('2014', random.nextInt(100)),
      new OrdinalSales('2015', random.nextInt(100)),
      new OrdinalSales('2016', random.nextInt(100)),
      new OrdinalSales('2017', random.nextInt(100)),
    ];

    return [
      new charts.Series<OrdinalSales, String>(
        id: 'Desktop',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: desktopSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Tablet',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: tabletSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Mobile',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: mobileSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Other',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: otherSalesData,
      )
    ];
  }
  // EXCLUDE_FROM_GALLERY_DOCS_END

  @override
  Widget build(BuildContext context) {
    return new charts.BarChart(
      seriesList,
      animate: animate,
      barGroupingType: charts.BarGroupingType.grouped,
      // Add the legend behavior to the chart to turn on legends.
      // By default the legend will display above the chart.
      //
      // To change the symbol used in the legend, set the renderer attribute of
      // symbolRendererKey to a SymbolRenderer.
      behaviors: [new charts.SeriesLegend()],
      defaultRenderer: new charts.BarRendererConfig(
          symbolRenderer: new IconRenderer(Icons.cloud)),
    );
  }

  /// Create series list with multiple series
  static List<charts.Series<OrdinalSales, String>> _createSampleData() {
    final desktopSalesData = [
      new OrdinalSales('2014', 5),
      new OrdinalSales('2015', 25),
      new OrdinalSales('2016', 100),
      new OrdinalSales('2017', 75),
    ];

    final tabletSalesData = [
      new OrdinalSales('2014', 25),
      new OrdinalSales('2015', 50),
      new OrdinalSales('2016', 10),
      new OrdinalSales('2017', 20),
    ];

    final mobileSalesData = [
      new OrdinalSales('2014', 10),
      new OrdinalSales('2015', 15),
      new OrdinalSales('2016', 50),
      new OrdinalSales('2017', 45),
    ];

    final otherSalesData = [
      new OrdinalSales('2014', 20),
      new OrdinalSales('2015', 35),
      new OrdinalSales('2016', 15),
      new OrdinalSales('2017', 10),
    ];

    return [
      new charts.Series<OrdinalSales, String>(
        id: 'Desktop',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: desktopSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Tablet',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: tabletSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Mobile',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: mobileSalesData,
      ),
      new charts.Series<OrdinalSales, String>(
        id: 'Other',
        domainFn: (OrdinalSales sales, _) => sales.year,
        measureFn: (OrdinalSales sales, _) => sales.sales,
        data: otherSalesData,
      )
    ];
  }
}

/// Sample ordinal data type.
class OrdinalSales {
  final String year;
  final int sales;

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