Flutter图形计算插件flutter_graph_calculator的使用

本指南将帮助您了解如何在Flutter应用中使用flutter_graph_calculator插件。通过这个插件，您可以创建交互式且可自定义的图表。

特性

• 绘制数学函数图。
• 自定义图表外观，包括颜色、网格设置等。
• 轻松地将图表集成到您的Flutter应用中。

安装

首先，在您的pubspec.yaml文件中添加依赖：

flutter pub add flutter_graph_calculator

使用

以下是一个简单的示例，展示如何在Flutter应用中使用flutter_graph_calculator插件。

主要代码

import 'package:flutter/material.dart';
import 'package:flutter_graph_calculator/flutter_graph_calculator.dart';

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

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

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        colorScheme: ColorScheme.fromSeed(seedColor: Colors.black),
        useMaterial3: true,
      ),
      home: const HomePage(),
    );
  }
}

class HomePage extends StatefulWidget {
  const HomePage({Key? key}) : super(key: key);

  @override
  State<HomePage> createState() => _HomePageState();
}

class _HomePageState extends State<HomePage> {
  // 创建一个GraphController实例，用于控制图表
  var graphController = GraphController(
    graph: Graph(
      gridStep: 100, // 网格间隔
      numbersStyle: const TextStyle(color: Colors.black), // 数字样式
    ),
  );

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      body: Center(
        child: GraphWidget(
          graphController: graphController,
          size: MediaQuery.of(context).size, // 设置图表大小
        ),
      ),
      floatingActionButtonLocation: FloatingActionButtonLocation.endFloat,
      floatingActionButton: Column(
        mainAxisAlignment: MainAxisAlignment.end,
        children: [
          // 添加一个按钮，用于绘制新的函数
          FloatingActionButton(
            backgroundColor: Colors.white,
            child: const Icon(Icons.line_axis_rounded),
            onPressed: () {
              setState(() {
                // 添加一个二次函数
                graphController.addFunction(GraphFunction(
                    function: (x) {
                      return x * x; // 二次函数 y = x^2
                    },
                    color: Colors.red)); // 设置函数的颜色为红色
              });
            },
          ),
          const SizedBox(
            height: 10,
          ),
          // 添加一个按钮，用于重置图表
          FloatingActionButton(
            backgroundColor: Colors.white,
            child: const Icon(Icons.center_focus_strong),
            onPressed: () {
              setState(() {
                // 重置图表
                graphController.backToHome();
              });
            },
          )
        ],
      ),
    );
  }
}

解释

1. 导入库：

   import 'package:flutter/material.dart';
   import 'package:flutter_graph_calculator/flutter_graph_calculator.dart';

2. 创建主应用类：

   void main() {
     runApp(const MyApp());
   }
   
   class MyApp extends StatelessWidget {
     const MyApp({Key? key}) : super(key: key);
   
     @override
     Widget build(BuildContext context) {
       return MaterialApp(
         title: 'Flutter Demo',
         theme: ThemeData(
           colorScheme: ColorScheme.fromSeed(seedColor: Colors.black),
           useMaterial3: true,
         ),
         home: const HomePage(),
       );
     }
   }

3. 创建主页状态类：

   class HomePage extends StatefulWidget {
     const HomePage({Key? key}) : super(key: key);
   
     @override
     State<HomePage> createState() => _HomePageState();
   }
   
   class _HomePageState extends State<HomePage> {
     var graphController = GraphController(
       graph: Graph(
         gridStep: 100,
         numbersStyle: const TextStyle(color: Colors.black),
       ),
     );
   
     @override
     Widget build(BuildContext context) {
       return Scaffold(
         body: Center(
           child: GraphWidget(
             graphController: graphController,
             size: MediaQuery.of(context).size,
           ),
         ),
         floatingActionButtonLocation: FloatingActionButtonLocation.endFloat,
         floatingActionButton: Column(
           mainAxisAlignment: MainAxisAlignment.end,
           children: [
             FloatingActionButton(
               backgroundColor: Colors.white,
               child: const Icon(Icons.line_axis_rounded),
               onPressed: () {
                 setState(() {
                   graphController.addFunction(GraphFunction(
                       function: (x) {
                         return x * x;
                       },
                       color: Colors.red));
                 });
               },
             ),
             const SizedBox(
               height: 10,
             ),
             FloatingActionButton(
               backgroundColor: Colors.white,
               child: const Icon(Icons.center_focus_strong),
               onPressed: () {
                 setState(() {
                   graphController.backToHome();
                 });
               },
             )
           ],
         ),
       );
     }
   }