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Sample code for creating a mid-circle radial gauge widget with Flutter. See https://rm3l.org/creating-a-mid-circle-radial-gauge-in-flutter/ for more details.
import 'dart:math';
import 'package:flutter/material.dart';
class MyCustomRadialGauge extends StatefulWidget {
@override
_MyCustomRadialGaugeState createState() => _MyCustomRadialGaugeState();
}
class _MyCustomRadialGaugeState extends State<MyCustomRadialGauge>
with SingleTickerProviderStateMixin {
Animation<double> _animation;
AnimationController _controller;
double _fraction = 0.0;
@override
void initState() {
super.initState();
_controller = AnimationController(
duration: const Duration(milliseconds: 1000), vsync: this);
_animation = Tween(begin: 0.0, end: 1.0).animate(_controller)
..addListener(() {
setState(() {
_fraction = _animation.value;
});
});
_controller.forward();
}
@override
void dispose() {
_controller.dispose();
super.dispose();
}
@override
Widget build(BuildContext context) {
final screenWidth = MediaQuery.of(context).size.width;
final screenHeight = MediaQuery.of(context).size.height;
final maxValue = 1700;
final current = 1234.5;
return CustomPaint(
foregroundPainter:
_MyCustomRadialGaugePainter(_fraction, maxValue, current),
child: Container(
padding: EdgeInsets.only(top: screenHeight * 0.0875),
width: screenWidth * 0.34,
child: Center(
child: Column(
children: [
Container(
height: screenHeight * 0.01,
color: Colors.transparent,
),
Text(
'${(100 * current / maxValue).toStringAsFixed(0)}%',
style: TextStyle(color: Colors.grey, fontSize: 50.0),
),
Container(
height: screenHeight * 0.027,
color: Colors.transparent,
),
Container(
height: screenHeight * 0.04,
child: Text('Title', style: TextStyle(fontSize: 22.0)))
],
),
),
),
);
}
}
class _MyCustomRadialGaugePainter extends CustomPainter {
final num maxValue;
final num current;
double _fraction;
_MyCustomRadialGaugePainter(this._fraction, this.maxValue, this.current);
@override
void paint(Canvas canvas, Size size) {
final complete = Paint()
..color = Colors.blue
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke
..strokeWidth = 13.0;
final line = Paint()
..color = const Color(0xFFE9E9E9)
..strokeCap = StrokeCap.round
..style = PaintingStyle.stroke
..strokeWidth = 13.0;
final center = Offset(size.width / 2, size.height / 2);
final radius = min(size.width, size.height);
final startAngle = -7 * pi / 6;
final sweepAngle = 4 * pi / 3;
canvas.drawArc(Rect.fromCircle(center: center, radius: radius), startAngle,
sweepAngle, false, line);
final arcAngle = (sweepAngle) * (current / maxValue);
canvas.drawArc(Rect.fromCircle(center: center, radius: radius), startAngle,
arcAngle * _fraction, false, complete);
final lowerBoundText = TextPainter(textDirection: TextDirection.ltr)
..text = TextSpan(text: '0', style: TextStyle(color: Colors.grey))
..layout(minWidth: 0, maxWidth: double.maxFinite);
lowerBoundText.paint(
canvas, Offset(-size.width * 0.42, size.height / 1.22));
final upperBoundText = TextPainter(textDirection: TextDirection.ltr)
..text = TextSpan(text: '$maxValue', style: TextStyle(color: Colors.grey))
..layout(minWidth: 0, maxWidth: double.maxFinite);
upperBoundText.paint(canvas, Offset(size.width / 0.77, size.height / 1.22));
}
@override
bool shouldRepaint(_MyCustomRadialGaugePainter oldDelegate) =>
oldDelegate._fraction != _fraction;
}
@rm3l

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@rm3l rm3l commented Dec 3, 2020

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