How to Make Radial Car Speed Meter Like Gauge in Flutter

Table of Contents

Introduction

Creating a radial car speed meter like gauge in Flutter can enhance the user experience of your app, especially if it’s related to vehicle tracking or racing. A speed meter gauge provides a visually appealing way to display speed, and with Flutter, you can achieve this with ease. In this blog post, we’ll guide you through the process of creating a radial car speed meter like gauge in Flutter.

Understanding the Basics

To create a radial car speed meter, you need to understand the basics of Flutter and its libraries. You’ll be using the CustomPaint widget to create the gauge. The CustomPaint widget allows you to create custom graphics by providing a Canvas to draw on.

Creating the Gauge

To create the gauge, you’ll need to create a custom widget that extends the CustomPainter class. This class will override the paint method, which is where you’ll draw the gauge.

“`dart

class SpeedMeter extends CustomPainter {

@override

void paint(Canvas canvas, Size size) {

// Draw the gauge

Paint paint = Paint()

..color = Colors.black

..strokeWidth = 10;

canvas.drawCircle(Offset(size.width / 2, size.height / 2), size.width / 2, paint);

}

@override

bool shouldRepaint(CustomPainter oldDelegate) => false;

}

“`

Adding the Needle

The needle is the part of the gauge that moves to indicate the speed. To create the needle, you’ll need to calculate the angle of the needle based on the speed.

“`dart

class SpeedMeter extends CustomPainter {

final double speed;

SpeedMeter(this.speed);

@override

void paint(Canvas canvas, Size size) {

// Draw the gauge

Paint paint = Paint()

..color = Colors.black

..strokeWidth = 10;

canvas.drawCircle(Offset(size.width / 2, size.height / 2), size.width / 2, paint);

// Draw the needle

double angle = speed * 3.6; // Assuming the speed is in km/h

canvas.save();

canvas.translate(size.width / 2, size.height / 2);

canvas.rotate(angle * 3.14159 / 180);

Paint needlePaint = Paint()

..color = Colors.red

..strokeWidth = 5;

canvas.drawLine(Offset(0, 0), Offset(0, -size.width / 2), needlePaint);

canvas.restore();

}

@override

bool shouldRepaint(CustomPainter oldDelegate) => true;

}

“`

Using the Gauge

To use the gauge, you’ll need to create a widget that uses the SpeedMeter custom painter.

“`dart

class SpeedGauge extends StatefulWidget {

@override

SpeedGaugeState createState() => SpeedGaugeState();

}

class _SpeedGaugeState extends State {

double _speed = 0;

@override

Widget build(BuildContext context) {

return CustomPaint(

painter: SpeedMeter(_speed),

child: Container(

width: 200,

height: 200,

);

}

“`

Conclusion

Creating a radial car speed meter like gauge in Flutter is a relatively simple process. By using the CustomPaint widget and creating a custom painter, you can create a gauge that displays the speed in a visually appealing way.