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samples/web/charts/lib/behaviors/selection_line_highlight.dart

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// 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.
// 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 SelectionLineHighlight extends StatelessWidget {
final List<charts.Series<dynamic, num>> seriesList;
final bool? animate;
const SelectionLineHighlight(this.seriesList, {this.animate, Key? key})
: super(key: key);
/// Creates a [LineChart] with sample data and no transition.
factory SelectionLineHighlight.withSampleData() {
return SelectionLineHighlight(
_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 SelectionLineHighlight.withRandomData() {
return SelectionLineHighlight(_createRandomData());
}
/// Create random data.
static List<charts.Series<LinearSales, num>> _createRandomData() {
final random = Random();
final data = [
LinearSales(0, random.nextInt(100)),
LinearSales(1, random.nextInt(100)),
LinearSales(2, random.nextInt(100)),
LinearSales(3, random.nextInt(100)),
];
return [
charts.Series<LinearSales, int>(
id: 'Sales',
domainFn: (LinearSales sales, _) => sales.year,
measureFn: (LinearSales sales, _) => sales.sales,
data: data,
)
];
}
// EXCLUDE_FROM_GALLERY_DOCS_END
@override
Widget build(BuildContext context) {
// This is just a simple line chart with a behavior that highlights the
// selected points along the lines. A point will be drawn at the selected
// datum's x,y coordinate, and a vertical follow line will be drawn through
// it.
//
// A [Charts.LinePointHighlighter] behavior is added manually to enable the
// highlighting effect.
//
// As an alternative, [defaultInteractions] can be set to true to include
// the default chart interactions, including a LinePointHighlighter.
return charts.LineChart(seriesList, animate: animate, behaviors: [
// Optional - Configures a [LinePointHighlighter] behavior with a
// vertical follow line. A vertical follow line is included by
// default, but is shown here as an example configuration.
//
// By default, the line has default dash pattern of [1,3]. This can be
// set by providing a [dashPattern] or it can be turned off by passing in
// an empty list. An empty list is necessary because passing in a null
// value will be treated the same as not passing in a value at all.
charts.LinePointHighlighter(
showHorizontalFollowLine:
charts.LinePointHighlighterFollowLineType.none,
showVerticalFollowLine:
charts.LinePointHighlighterFollowLineType.nearest),
// Optional - By default, select nearest is configured to trigger
// with tap so that a user can have pan/zoom behavior and line point
// highlighter. Changing the trigger to tap and drag allows the
// highlighter to follow the dragging gesture but it is not
// recommended to be used when pan/zoom behavior is enabled.
charts.SelectNearest(eventTrigger: charts.SelectionTrigger.tapAndDrag)
]);
}
/// Create one series with sample hard coded data.
static List<charts.Series<LinearSales, int>> _createSampleData() {
final data = [
LinearSales(0, 5),
LinearSales(1, 25),
LinearSales(2, 100),
LinearSales(3, 75),
];
return [
charts.Series<LinearSales, int>(
id: 'Sales',
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);
}