Axis in Flutter Radial Gauge (SfRadialGauge)

18 Nov 201824 minutes to read

The radial axis is a circular arc in which a set of values are displayed along a linear or custom scale based on the design requirements. Axis elements such as labels, ticks, and axis line can be easily customized with built-in properties.

Axis customization

Axis minimum and maximum

The minimum and maximum properties of an axis can be used to customize the axis range. The default value of minimum is 0, and the default value of maximum is 100.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(minimum: -60, maximum: 60)
            ]
          ),
        ),
      ),
    );
  }
}

axis range

Angle Customization

The start and end angles of radial axis can be customized using the startAngle and endAngle properties.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(startAngle: 180, endAngle: 90)
            ]
          ),
        ),
      ),
    );
  }
}

axis angle customization

Radius customization

The radius of the radial axis can be customized using the radiusFactor property. The default value of the radiusFactor is 0.95. The value of radiusFactor ranges from 0 to 1. For example, When the radiusFactor value is 1, the full radius will be considered for rendering the axis, and when the radiusFactor value is 0.5, then half of the radius value will be considered for rendering the circle.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(),
              RadialAxis(radiusFactor: 0.5)
            ]
          ),
        ),
      ),
    );
  }
}

axis radius customization

Axis position customization

The position of the radial axis can be customized using the centerX and centerY values. The default value of centerX and centerY properties is 0.5. Therefore, the axis will be positioned in the center of provided size of gauge.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(startAngle: 270, endAngle: 270, interval: 10),
              RadialAxis(
                centerY: 0.55, 
                centerX: 0.35,
                radiusFactor: 0.3, 
                startAngle: 270,
                endAngle: 270, 
                interval: 20
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis position customization

Positioning axis based on its angle

The canScaleToFit property of radial axis allows you to position the axis and its features based on the provided start and end angle. By default, the canScaleToFit is false, therefore the axis will be positioned based on the centerX and centerY value.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                startAngle: 180, 
                endAngle: 0,
                interval: 10,
                canScaleToFit: true
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis fit to scale

Axis label rotation

The axis label can be rotated based on its current angle using the canRotateLabels property of axis. The default value of canRotateLabels is false.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(canRotateLabels: true)
            ]
          ),
        ),
      ),
    );
  }
}

axis label rotation

Edge label customization

The visibility of the first and last labels of an axis can be customized using the showFirstLabel and showLastLabel properties.

  • showFirstLabel – Enables or disables the first label of the axis.
  • showLastLabel – Enables or disables the last label of the axis.

The default value of both the showFirstLabel and the showLastLabel properties is true.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                interval: 1, 
                showFirstLabel: false,
                startAngle: 270, 
                endAngle: 270, 
                minimum: 0, 
                maximum: 12
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis edge label

Axis direction customization

The direction of radial axis can be customized by its isInversed property.

When the isInversed property is true, the axis can be placed in a counter-clockwise direction. When the isInversed property is set to false, the axis will be positioned in a clockwise direction.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis( isInversed: true)]
          ),
        ),
      ),
    );
  }
}

axis direction

Maximum number of labels per 100 logical pixels

By default, a maximum of three labels are displayed for each 100 logical pixels in an axis. The maximum number of labels that should be present within 100 logical pixels length can be customized using the maximumLabels property of the axis. This property is applicable only for automatic range calculation and will not work if you set value for interval property of an axis.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis( maximumLabels: 5)]
          ),
        ),
      ),
    );
  }
}

axis maximum labels

Interval

The interval between labels can be customized using the interval property of axis.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(interval: 20)
            ]
          ),
        ),
      ),
    );
  }
}

axis label interval

Axis line customization

The radial axis line can be customized using the axisLineStyle property. The following properties can be customized using axisLineStyle.

  • thickness – Customizes the thickness of axis line.
  • thicknessUnit – Allows to specify the thickness of the axis either in logical pixel or factor. Its default value is logicalPixel.
  • color – Customizes the color of the axis line.
  • cornerStyle – Allows to customize the corner of the axis line.
  • dashArray – Allows to customize the axis line as dashed circular arc.
  • gradient - Allows to apply the gradient for axis line.
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                axisLineStyle: AxisLineStyle(
                  thickness: 0.1,
                  thicknessUnit: GaugeSizeUnit.factor, 
                  color: Colors.deepPurple
                )
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis line customization

Rounded Corners

The cornerStyle property of axisLineStyle specifies the corner type for axis line. The corners can be customized using the bothFlat, bothCurve, startCurve, and endCurve options. The default value of this property is bothFlat.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                axisLineStyle: AxisLineStyle(
                  thickness: 15,              
                  cornerStyle: CornerStyle.bothCurve
                )
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis corner

Dashed axis line

The dashArray property of axisLineStyle allows to render the dashed axis line.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                axisLineStyle: AxisLineStyle(dashArray: <double>[5, 5])
              )
            ]
          ),
        ),
      ),
    );
  }
}

dashed axis line

Gradient support

The gradient property of axisLineStyle allows to specify the smooth color transition to the axis line by specifying the different colors based on provided factor value.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                axisLineStyle: AxisLineStyle(
                  thickness: 0.1,
                  thicknessUnit: GaugeSizeUnit.factor,
                  gradient: const SweepGradient(
                    colors: <Color>[Color(0xFFFF7676), Color(0xFFF54EA2)],
                    stops: <double>[0.25, 0.75]
                  )
                )
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis gradient line

Axis line visibility

The visibility of the axis line can be customized using the showAxisLine property of axis. By default, this property is set to true.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(showAxisLine: false)
            ]
          ),
        ),
      ),
    );
  }
}

axis line visibility

Background color support

Radial gauge allows customizing its background color using backgroundColor property.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            backgroundColor: Colors.lightBlue,
            axes: <RadialAxis>[RadialAxis()]
          )
        ),
      ),
    );
  }
}

axisbackground color

Background image support

Radial axis allows to add an image frame as its background using backgroundImage property.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                backgroundImage: const AssetImage('images/gauge_background.png'),
              )
            ],
          ),
        ),
      ),
    );
  }
}

The following example demonstrates a more advanced usage with background image, custom styling, pointers, and annotations:

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: Padding(
            padding: const EdgeInsets.fromLTRB(10, 0, 10, 0),
            child: SfRadialGauge(
              axes: <RadialAxis>[
                RadialAxis(
                  showAxisLine: false,
                  radiusFactor: 1,
                  showLastLabel: false,
                  canRotateLabels: true,
                  tickOffset: 0.32,
                  offsetUnit: GaugeSizeUnit.factor,
                  onLabelCreated: axisLabelCreated,
                  startAngle: 270,
                  endAngle: 270,
                  labelOffset: 0.05,
                  maximum: 360,
                  minimum: 0,
                  interval: 30,
                  minorTicksPerInterval: 4,
                  axisLabelStyle: const GaugeTextStyle(color: Color(0xFF949494)),
                  minorTickStyle: const MinorTickStyle(
                    color: Color(0xFF616161),
                    thickness: 1.6,
                    length: 0.058,
                    lengthUnit: GaugeSizeUnit.factor
                  ),
                  majorTickStyle: const MajorTickStyle(
                    color: Color(0xFF949494),
                    thickness: 2.3,
                    length: 0.087,
                    lengthUnit: GaugeSizeUnit.factor
                  ),
                  backgroundImage: const AssetImage('images/dark_theme_gauge.png'),
                  pointers: <GaugePointer>[
                    MarkerPointer(
                      value: 90,
                      color: const Color(0xFFDF5F2D),
                      enableAnimation: true,
                      animationDuration: 1200,
                      markerOffset: 0.71,
                      offsetUnit: GaugeSizeUnit.factor,
                      markerType: MarkerType.triangle,
                      markerHeight: 10,
                      markerWidth: 15
                    )
                  ],
                  annotations: <GaugeAnnotation>[
                    GaugeAnnotation(
                      angle: 270,
                      positionFactor: 0.025,
                      widget: const Text(
                        '90',
                        style: TextStyle(
                          color: Color(0xFFDF5F2D),
                          fontWeight: FontWeight.bold,
                          fontSize: 22
                        )
                      )
                    )
                  ]
                )
              ],
            ),
          )
        ),
      ),
    );
  }

  void axisLabelCreated(AxisLabelCreatedArgs args) {
    if (args.text == '90') {
      args.text = 'E';
      args.labelStyle = const GaugeTextStyle(color: Color(0xFFDF5F2D));
    } else {
      if (args.text == '0') {
        args.text = 'N';
      } else if (args.text == '180') {
        args.text = 'S';
      } else if (args.text == '270') {
        args.text = 'W';
      }
      args.labelStyle = const GaugeTextStyle(color: Color(0xFFFFFFFF));
    }
  }
}

axis background image

Label style customization

The axis labels can be customized using the axisLabelStyle property of axis. The following properties can be customized using the axisLabelStyle.

  • color – Allows to customize the color of the labels.
  • fontFamily – Allows to specify the font family for labels.
  • fontStyle – Allows to specify the font style for labels.
  • fontWeight – Allows to specify the font weight for labels.
  • fontSize – Allows to specify the font size for labels.
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                axisLabelStyle: const GaugeTextStyle(
                  color: Colors.red, 
                  fontSize: 15,
                  fontStyle: FontStyle.italic,
                  fontWeight: FontWeight.bold, 
                  fontFamily: 'Times'
                )
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis label customization

Formatting axis label

The following property of the axis allows to customize the axis label text:

  • labelFormat - Allows to add prefix or suffix with the axis labels.
import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(labelFormat: '{value}m')
            ]
          ),
        ),
      ),
    );
  }
}

axis label format

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';
import 'package:intl/intl.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(numberFormat: NumberFormat.compactSimpleCurrency())
            ]
          ),
        ),
      ),
    );
  }
}

axis number format

Label visibility

The showLabels property of axis allows to enable or disable the visibility of labels. The default value of the property is true.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(showLabels: false )]
          ),
        ),
      ),
    );
  }
}

axis label visibility

Tick customization

The major and minor tick lines of an axis can be customized using the majorTickStyle and minorTickStyle properties respectively. The following properties can be customized for both the major and the minor ticks:

  • color – Allows to customize the tick color.

  • thickness – Allows to customize the thickness of ticks.

  • length – Specifics the length of ticks.

  • lengthUnit – Allows to specify the tick length either in logical pixels or factor.

  • dashArray – Specify the dash array to draw the dashed tick line.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                majorTickStyle: const MajorTickStyle(
                  length: 0.1,
                  lengthUnit: GaugeSizeUnit.factor, 
                  thickness: 1.5, 
                  color: Colors.black
                ),
                minorTickStyle: const MinorTickStyle(
                  length: 0.05,
                  lengthUnit: GaugeSizeUnit.factor, 
                  thickness: 1.5, 
                  color: Colors.black
                )
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis tick customization

Dashed tick lines

The dashArray property of both the majorTickStyle and minorTickStyle allows to draw the tick line as dashed line.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                majorTickStyle: const MajorTickStyle(length: 20, dashArray: <double>[5, 2.5]),
                minorTickStyle: const MinorTickStyle(length: 15, dashArray: <double>[3, 2.5])
              )
            ]
          ),
        ),
      ),
    );
  }
}

dashed tick lines

Minor tick interval

The major ticks are generated based on the interval property. Like major ticks, the minor ticks are calculated using the minorTicksPerInterval property of axis. By default, the value of this property is 1.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(minorTicksPerInterval: 4),
            ]
          ),
        ),
      ),
    );
  }
}

minor tick line

Tick line visibility

The showTicks property of the axis is used to enable or disable the visibility of both the major and the minor ticks of axis. The default value of this property is true.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(showTicks: false)]
          ),
        ),
      ),
    );
  }
}

tick line visibility

Label and tick Placement

The radial axis allows to position the labels and ticks either inside or outside the axis line using the labelsPosition and ticksPosition properties. By default, both labels and ticks are positioned inside the axis.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(
              labelsPosition: ElementsPosition.outside,
            ticksPosition: ElementsPosition.outside)]
          ),
        ),
      ),
    );
  }
}

label and tick placement

Tick position customization

The ticks can be moved near or far to the axis line using the tickOffset property. The offsetUnit property of axis allows to specify the tick offset either in factor or logical pixels, and the default value of offsetUnit is logicalPixel.

The default value of tick offset is 0. While setting offset for the ticks, the axis labels are also moved along with the ticks.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(
              tickOffset: 20)]
          ),
        ),
      ),
    );
  }
}

axis tick offset

The following code example shows how to add tick offset with the offsetUnit property of axis.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(
            axes: <RadialAxis>[
              RadialAxis(
                tickOffset: 0.2,
                labelOffset: 0.2, 
                offsetUnit: GaugeSizeUnit.factor
              )
            ]
          ),
        ),
      ),
    );
  }
}

axis tick and label offset

Label position customization

The labelOffset property allows to adjust the distance between the tick end and the labels. The offsetUnit property of axis allows to specify the label offset either in factor or logical pixels. By default, the value of the label offset is 15.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(
              labelOffset: 0.3, offsetUnit: GaugeSizeUnit.factor
              ),
            ]
          ),
        ),
      ),
    );
  }
}

axis label offset

The offsetUnit property of axis is common for both the tickOffset and labelOffset.

NOTE

GaugeSizeUnit allows to specify the value either in logical pixels or in factor. GaugeSizeUnit.factor ranges from 0 to 1. For example, when setting factor as 0.5, the half of axis radius value will be considered.

Multiple axis

The Radial Gauge allows you to add n number of radial axis in its axes collection. You can also customize individual axis added in the axes collection.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes: <RadialAxis>[ RadialAxis(minimum:  0 , maximum: 100, interval: 10,
            ticksPosition: ElementsPosition.outside,
            labelsPosition: ElementsPosition.outside,
            minorTicksPerInterval: 5,
            radiusFactor: 0.9, labelOffset: 15,
            minorTickStyle: const MinorTickStyle(thickness: 1.5,
              color: Color.fromARGB(255, 143, 20, 2),
              length: 0.07, lengthUnit: GaugeSizeUnit.factor),
            majorTickStyle: const MinorTickStyle(thickness: 1.5,
              color: Color.fromARGB(255, 143, 20, 2),
              length: 0.15, lengthUnit: GaugeSizeUnit.factor,),
            axisLineStyle: const AxisLineStyle( thickness: 3, 
              color: Color.fromARGB(255, 143, 20, 2), ),
            axisLabelStyle: const GaugeTextStyle(fontSize: 12,
              color:Color.fromARGB(255, 143, 20, 2),),),
            RadialAxis(minimum:  0 , maximum: 60, interval: 10,
              radiusFactor:  0.6, labelOffset: 15, isInversed: true,
              minorTicksPerInterval: 5,
              minorTickStyle: const MinorTickStyle(color: Colors.black, thickness: 1.5,
                  lengthUnit: GaugeSizeUnit.factor, length: 0.07),
              majorTickStyle: const MajorTickStyle(color: Colors.black, thickness: 1.5,
                  lengthUnit: GaugeSizeUnit.factor, length: 0.15),
              axisLineStyle: const AxisLineStyle(color: Colors.black, thickness: 3, ),
              axisLabelStyle: const GaugeTextStyle(color:  Colors.black, fontSize: 12)),
            ],
          )
        ),
      );
  }
}

axis label offset

Events

onLabelCreated

The onLabelCreated event is called when an axis label is created. The following properties can be customized for the corresponding axis label when this event args:

  • text – Allows to customize the text property of label.
  • labelStyle – Customizes the label color, font style, font family, and font weight.
  • canRotate – Specifies whether to rotate the label based on its current angle.

NOTE

If both axisLabelStyle property of radial axis and labelStyle property of the onLabelCreated event args are set, the values of the labelStyle property of the event args will take precedence.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(
              onLabelCreated:axisLabelCreated,),
            ]
          ),
        ),
      ),
    );
  }

  void axisLabelCreated(AxisLabelCreatedArgs args){
    if(args.text == '100'){
      args.labelStyle = const GaugeTextStyle(color: Colors.red,fontStyle: FontStyle.italic,
          fontFamily: 'Times', fontWeight: FontWeight.bold, fontSize: 15);
      args.canRotate = true;
      args.text = '100 %';
    }
  }
}

axis label offset

onAxisTapped

The onAxisTapped event is called when an axis is tapped. The corresponding axis value at the tapped position will be got from the event.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
        child: SfRadialGauge(
          axes:<RadialAxis>[RadialAxis(
              onAxisTapped: axisTapped),
            ]
          ),
        ),
      ),
    );
  }

  void axisTapped(double tappedValue){
    // Handle the tapped value
  }
}

Custom scale

Radial gauge allows you to display a set of values along with a custom scale based on your business logic using the onCreateAxisRenderer event of the axis. The onCreateAxisRenderer event allows returning the custom renderer for the axis. In that, we can override methods of RadialAxisRenderer to create the custom axis.

import 'package:flutter/material.dart';
import 'package:syncfusion_flutter_gauges/gauges.dart';

void main() => runApp(const RadialGaugeDemo());

class RadialGaugeDemo extends StatelessWidget {
  const RadialGaugeDemo({Key? key}) : super(key: key);

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        body: Center(
          child: SfRadialGauge(axes: <RadialAxis>[
            RadialAxis(
              minimum: 0,
              maximum: 150,
              onCreateAxisRenderer: () {
                final CustomAxisRenderer renderer = CustomAxisRenderer();
                return renderer;
              },
            )
          ]),
        ),
      ),
    );
  }
}

class CustomAxisRenderer extends RadialAxisRenderer {
  CustomAxisRenderer() : super();

  /// Generated the 9 non-linear interval labels from 0 to 150
  /// instead of actual generated labels.
  @override
  List<CircularAxisLabel> generateVisibleLabels() {
    final List<CircularAxisLabel> visibleLabels = <CircularAxisLabel>[];
    for (num i = 0; i < 9; i++) {
      final double value = _calculateLabelValue(i);
      final CircularAxisLabel label = CircularAxisLabel(
          axis.axisLabelStyle, value.toInt().toString(), i, false);
      label.value = value;
      visibleLabels.add(label);
    }

    return visibleLabels;
  }

  /// Returns the factor(0 to 1) from value to place the labels in an axis.
  @override
  double valueToFactor(double value) {
    if (value >= 0 && value <= 2) {
      return (value * 0.125) / 2;
    } else if (value > 2 && value <= 5) {
      return (((value - 2) * 0.125) / (5 - 2)) + (1 * 0.125);
    } else if (value > 5 && value <= 10) {
      return (((value - 5) * 0.125) / (10 - 5)) + (2 * 0.125);
    } else if (value > 10 && value <= 20) {
      return (((value - 10) * 0.125) / (20 - 10)) + (3 * 0.125);
    } else if (value > 20 && value <= 30) {
      return (((value - 20) * 0.125) / (30 - 20)) + (4 * 0.125);
    } else if (value > 30 && value <= 50) {
      return (((value - 30) * 0.125) / (50 - 30)) + (5 * 0.125);
    } else if (value > 50 && value <= 100) {
      return (((value - 50) * 0.125) / (100 - 50)) + (6 * 0.125);
    } else if (value > 100 && value <= 150) {
      return (((value - 100) * 0.125) / (150 - 100)) + (7 * 0.125);
    } else {
      return 1;
    }
  }

  /// To return the label value based on interval
  double _calculateLabelValue(num value) {
    if (value == 0) {
      return 0;
    } else if (value == 1) {
      return 2;
    } else if (value == 2) {
      return 5;
    } else if (value == 3) {
      return 10;
    } else if (value == 4) {
      return 20;
    } else if (value == 5) {
      return 30;
    } else if (value == 6) {
      return 50;
    } else if (value == 7) {
      return 100;
    } else {
      return 150;
    }
  }
}

custom scale