Creating Beautiful Charts in Flutter with FL Chart
When it comes to data representation, charts are an essential tool for any mobile app. In this article, we’ll explore how to create stunning charts using the FL Chart package in Flutter.
Prerequisites
Before diving into the world of chart creation, make sure you have the following:
- The Flutter SDK
- A code editor (VS Code, Android Studio, or your preferred choice)
- Basic knowledge of Flutter
Setup
To follow along with this tutorial, download or clone the example app from GitHub. Install dependencies using the following command:
flutter pub get
Run the app with flutter run to ensure everything is working correctly.
Creating a Line Chart
Line charts are perfect for displaying annual price data for a company’s stock. We’ll use the LineChart widget to create a line chart.
dart
LineChartData(
lineBarsData: [
LineChartBarData(
spots: [
FlSpot(0, 10),
FlSpot(1, 20),
FlSpot(2, 30),
],
),
],
)
This will create a basic line chart with three data points.
Customizing the Tooltip
To add a touch event to the line chart and display a custom tooltip, use LineTouchData.
dart
LineTouchData(
touchCallback: (event) {
// Handle touch event
},
touchTooltipData: LineTouchTooltipData(
tooltipBgColor: Colors.blue,
tooltipRoundedRadius: 8,
),
)
This will display a blue tooltip with a rounded radius when the user touches the line chart.
Creating a Bar Chart
Bar charts are ideal for displaying categorical data. We’ll use the BarChart widget to create a bar chart.
dart
BarChartData(
barGroups: [
BarChartGroupData(
x: 0,
bars: [
BarChartRodData(
y: 10,
color: Colors.red,
),
],
),
],
)
This will create a basic bar chart with one data point.
Updating Chart Data
To update chart data dynamically, make the chart widget stateful and use the setState method.
“`dart
class BarChartWidget extends StatefulWidget {
@override
_BarChartWidgetState createState() => _BarChartWidgetState();
}
class _BarChartWidgetState extends State
@override
Widget build(BuildContext context) {
return BarChart(
BarChartData(
barGroups: [
BarChartGroupData(
x: 0,
bars: [
BarChartRodData(
y: 10,
color: Colors.red,
),
],
),
],
),
);
}
}
“`
This will update the bar chart data when the widget is rebuilt.
Creating a Pie Chart
Pie charts are perfect for displaying sector distribution for a user’s portfolio. We’ll use the PieChart widget to create a pie chart.
dart
PieChartData(
sections: [
PieChartSectionData(
value: 10,
color: Colors.blue,
),
],
)
This will create a basic pie chart with one section.
Other Graph Options
FL Chart offers a range of other graph options, including scatter charts and radar charts.
Animations with FL Chart
FL Chart provides beautiful animations and control over animation duration and curve.
dart
LineChartData(
swapAnimationDuration: Duration(milliseconds: 500),
swapAnimationCurve: Curves.easeInOut,
)
This will animate the line chart with a duration of 500 milliseconds and an ease-in-out curve.
By following this tutorial, you’ve learned how to create stunning charts using the FL Chart package in Flutter. With its powerful features and customization options, FL Chart is the perfect tool for any mobile app.