信号強度インジケーター

Signal strength indicator widget

Customizable signal strength indicator widget for Flutter.

Contents

• Requirements
• Features
• Installation
• Usage
• Parameters
• Feature requests and bugs

Requirements

• Dart SDK: >=3.0.0
• Flutter: >=3.10.0

Features

See the WEB DEMO.

Two visual variants:

• Bars — classic stacked bars with optional rounded corners, bevelled style, and spacing
• Sector — quarter-circle arc segments with optional rounded caps

Installation

Add this to your pubspec.yaml:

dependencies:
  signal_strength_indicator: ^0.5.0

Then run:

flutter pub get

Import in your Dart code:

import 'package:signal_strength_indicator/signal_strength_indicator.dart';

Usage

Bars

SignalStrengthIndicator.bars(
  value: 0.6,
  size: 40,
  barCount: 4,
  spacing: 0.2,
  activeColor: Colors.green,
  inactiveColor: Colors.grey.shade300,
)

Sector

SignalStrengthIndicator.sector(
  value: 0.6,
  size: 40,
  barCount: 4,
  spacing: 0.3,
  rounded: true,
)

Custom value range

SignalStrengthIndicator.bars(
  value: -65,     // e.g. RSSI in dBm
  minValue: -100,
  maxValue: -40,
  size: 40,
)

Threshold-based coloring with levels

levels is a Map<num, Color> mapping absolute thresholds to colors. A bar/segment becomes active and uses the color of the highest threshold that is <= the current value.

SignalStrengthIndicator.bars(
  value: signalValue,
  minValue: 0,
  maxValue: 100,
  size: 40,
  barCount: 3,
  levels: {
    33: Colors.red,
    66: Colors.orange,
    100: Colors.green,
  },
)

Rounded corners and bevelled bars

// Rounded corners
SignalStrengthIndicator.bars(
  value: 0.7,
  size: 40,
  radius: const Radius.circular(4),
)

// Bevelled (each bar steps up at an angle)
SignalStrengthIndicator.bars(
  value: 0.7,
  size: 40,
  bevelled: true,
)

Parameters

Common parameters (bars and sector)

Parameter	Type	Default	Description
value	num	required	Current signal value
minValue	num?	0.0	Minimum value of the range
maxValue	num?	1.0	Maximum value of the range
size	double?	icon theme size	Width and height of the widget
barCount	int	3	Number of bars/segments
activeColor	Color?	green	Color of active bars (when no levels)
inactiveColor	Color?	light green	Color of inactive bars
levels	Map<num, Color>?	—	Threshold-to-color mapping (absolute values)
spacing	double	0.2 / 0.3	Gap between bars as a fraction of bar size
margin	EdgeInsets	zero	Outer margin around the widget

Bars-only parameters

Parameter	Type	Default	Description
radius	Radius?	Radius.zero	Corner radius of each bar
bevelled	bool	false	Draw bars with an angled top edge

Sector-only parameters

Parameter	Type	Default	Description
rounded	bool	false	Use rounded arc cap ends

Feature requests and bugs

Please file feature requests and bugs at the issue tracker.