Flutter角度计算插件angles的使用

Dart Angles

官方Dart包

这个包提供了一个Angle类型，旨在消除诸如...deg或...rad这样的变量后缀的使用，以及手动的角度单位转换（如x * rad2deg等）。因此，这个包的存在意义不是为了提供功能，而是为了提高代码的可维护性，从而降低维护成本和错误。

角度可以从以下单位构造：度、弧度、百分度和转。

示例代码

// 各种定义半圈的方法:
a0 = Angle.degrees(180.0);
a1 = Angle.radians(math.pi);
a2 = Angle.turns(0.5);

a0.degrees; // = 180.0
a1.radians; // = 3.1415...
a2.turns;   // = 0.5

完整示例Demo

下面是一个完整的示例demo，演示了如何在Flutter项目中使用angles插件：

import 'package:flutter/material.dart';
import 'package:angles/angles.dart';
import 'dart:math' as math;

void main() {
  runApp(MyApp());
}

class MyApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Angles Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: MyHomePage(title: 'Angles Demo'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key? key, required this.title}) : super(key: key);

  final String title;

  @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  double _angleDegrees = 0.0;
  double _angleRadians = 0.0;
  double _angleTurns = 0.0;
  double _angleGradians = 0.0;

  void _setAngle(double value, String unit) {
    setState(() {
      switch (unit) {
        case 'degrees':
          _angleDegrees = value;
          break;
        case 'radians':
          _angleRadians = value;
          break;
        case 'turns':
          _angleTurns = value;
          break;
        case 'gradians':
          _angleGradians = value;
          break;
      }
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            Text(
              'Enter an angle and select the unit:',
            ),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  Expanded(
                    child: TextField(
                      onChanged: (value) {
                        if (value.isNotEmpty) {
                          _setAngle(double.parse(value), 'degrees');
                        } else {
                          _setAngle(0.0, 'degrees');
                        }
                      },
                      decoration: InputDecoration(
                        labelText: 'Degrees',
                      ),
                      keyboardType: TextInputType.number,
                    ),
                  ),
                  Expanded(
                    child: TextField(
                      onChanged: (value) {
                        if (value.isNotEmpty) {
                          _setAngle(double.parse(value), 'radians');
                        } else {
                          _setAngle(0.0, 'radians');
                        }
                      },
                      decoration: InputDecoration(
                        labelText: 'Radians',
                      ),
                      keyboardType: TextInputType.number,
                    ),
                  ),
                ],
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: Row(
                mainAxisAlignment: MainAxisAlignment.spaceEvenly,
                children: [
                  Expanded(
                    child: TextField(
                      onChanged: (value) {
                        if (value.isNotEmpty) {
                          _setAngle(double.parse(value), 'turns');
                        } else {
                          _setAngle(0.0, 'turns');
                        }
                      },
                      decoration: InputDecoration(
                        labelText: 'Turns',
                      ),
                      keyboardType: TextInputType.number,
                    ),
                  ),
                  Expanded(
                    child: TextField(
                      onChanged: (value) {
                        if (value.isNotEmpty) {
                          _setAngle(double.parse(value), 'gradians');
                        } else {
                          _setAngle(0.0, 'gradians');
                        }
                      },
                      decoration: InputDecoration(
                        labelText: 'Gradians',
                      ),
                      keyboardType: TextInputType.number,
                    ),
                  ),
                ],
              ),
            ),
            Padding(
              padding: const EdgeInsets.all(8.0),
              child: ElevatedButton(
                onPressed: () {
                  final angleFromDegrees = Angle.degrees(_angleDegrees);
                  final angleFromRadians = Angle.radians(_angleRadians);
                  final angleFromTurns = Angle.turns(_angleTurns);
                  final angleFromGradians = Angle.gradians(_angleGradians);

                  showDialog(
                    context: context,
                    builder: (context) => AlertDialog(
                      title: Text('Converted Angles'),
                      content: Column(
                        mainAxisSize: MainAxisSize.min,
                        crossAxisAlignment: CrossAxisAlignment.start,
                        children: [
                          Text('Degrees: ${angleFromDegrees.degrees}'),
                          Text('Radians: ${angleFromRadians.radians}'),
                          Text('Turns: ${angleFromTurns.turns}'),
                          Text('Gradians: ${angleFromGradians.gradians}'),
                        ],
                      ),
                      actions: [
                        TextButton(
                          onPressed: () => Navigator.pop(context),
                          child: Text('Close'),
                        ),
                      ],
                    ),
                  );
                },
                child: Text('Convert'),
              ),
            ),
          ],
        ),
      ),
    );
  }
}

文档

构造函数

• Angle.degrees(x)
• Angle.radians(x)
• Angle.gradians(x)
• Angle.turns(x)

访问器

• .degrees()
• .radians()
• .gradians()
• .turns()

三角函数

• .sin()
• .cos()
• .tan()
• Angle.asin(x)
• Angle.acos(x)
• Angle.atan(x)
• Angle.atan2(y, x)
• Angle.atanFullTurn(y, x)
• Angle.cartesian(x, y)

实用函数

• .toString()
• .approximately(other, range)
• .ratio(other)
• .normalized

所有算术和关系运算符都已定义在角度上。