flutter3+dart3聊天室|Flutter3跨平台仿微信App语音聊天/朋友圈

全新研发flutter3+dart3+photo_view跨多端仿微信App界面聊天Flutter3-Chat。

flutter3-chat基于最新跨全平台技术flutter3+dart3+material-design+shared_preferences+easy_refresh构建的仿微信APP界面聊天实例项目。实现发送图文表情消息/gif大图、长按仿微信语音操作面板、图片预览、红包及朋友圈等功能。

技术架构

编辑器：Vscode
框架技术：Flutter3.16.5+Dart3.2.3
UI组件库：material-design3
弹窗组件：showDialog/SimpleDialog/showModalBottomSheet/AlertDialog
图片预览：photo_view^0.14.0
本地缓存：shared_preferences^2.2.2
下拉刷新：easy_refresh^3.3.4
toast提示：toast^0.3.0
网址预览组件：url_launcher^6.2.4

Flutter3.x开发跨平台项目，性能有了大幅度提升，官方支持编译到android/ios/macos/windows/linux/web等多平台，未来可期！

项目构建目录

通过 flutter create app_project 命令即可快速创建一个跨平台初始化项目。

通过命令创建项目后，项目结构就如上图所示。

需要注意：flutter项目基于dart语音开发，需要首先配置Dart SDK和Flutter SDK开发环境，大家可以去官网查看配置文档。

https://flutter.dev/

https://flutter.cn/

https://pub.flutter-io.cn/

https://www.dartcn.com/

另外使用VScode编辑器开发项目，可自行安装Flutter / Dart扩展插件。

目前flutter3-chat聊天app已经同步到我的原创作品集。

https://gf.bilibili.com/item/detail/1105158011

由于flutter3支持编译到windows，大家可以开发初期在windows上面调试，后期release apk到手机上。

通过如下命令即可运行到windows平台

flutter run -d windows

运行后默认窗口大小为1280x720，可以修改windows/runner/main.cpp文件里面的窗口尺寸。

同样，可以通过 flutter run -d chrome 命令运行到web上预览。

假如在没有真机的情况下，我们可以选择模拟器调试。目前市面上有很多类型模拟器，他们使用adb连接时都会有不同的默认端口，下面列出了一些常用的模拟器及端口号。通过adb connect连接上指定模拟器之后，执行flutter run命令即可运行项目到模拟器上面。

flutter3实现圆角文本框及渐变按钮

Container(
  height: 40.0,
  margin: const EdgeInsets.symmetric(vertical: 5.0, horizontal: 30.0),
  decoration: BoxDecoration(
    color: Colors.white,
    border: Border.all(color: const Color(0xffdddddd)),
    borderRadius: BorderRadius.circular(15.0),
  ),
  child: Row(
    children: [
      Expanded(
        child: TextField(
          keyboardType: TextInputType.phone,
          controller: fieldController,
          decoration: InputDecoration(
            hintText: '输入手机号',
            suffixIcon: Visibility(
              visible: authObj['tel'].isNotEmpty,
              child: InkWell(
                hoverColor: Colors.transparent,
                highlightColor: Colors.transparent,
                splashColor: Colors.transparent,
                onTap: handleClear,
                child: const Icon(Icons.clear, size: 16.0,),
              )
            ),
            contentPadding: const EdgeInsets.symmetric(vertical: 0, horizontal: 12.0),
            border: const OutlineInputBorder(borderSide: BorderSide.none),
          ),
          onChanged: (value) {
            setState(() {
              authObj['tel'] = value;
            });
          },
        ),
      )
    ],
  ),
),

按钮渐变则是通过Container组件的decotaion里面的gradient属性设置渐变效果。

Container(
  margin: const EdgeInsets.symmetric(vertical: 10.0, horizontal: 30.0),
  decoration: BoxDecoration(
    borderRadius: BorderRadius.circular(15.0),
    // 自定义按钮渐变色
    gradient: const LinearGradient(
      begin: Alignment.topLeft,
      end: Alignment.bottomRight,
      colors: [
        Color(0xFF0091EA), Color(0xFF07C160)
      ],
    )
  ),
  child: SizedBox(
    width: double.infinity,
    height: 45.0,
    child: FilledButton(
      style: ButtonStyle(
        backgroundColor: MaterialStateProperty.all(Colors.transparent),
        shadowColor: MaterialStateProperty.all(Colors.transparent),
        shape: MaterialStatePropertyAll(
          RoundedRectangleBorder(borderRadius: BorderRadius.circular(15.0))
        )
      ),
      onPressed: handleSubmit,
      child: const Text('登录', style: TextStyle(fontSize: 18.0),),
    ),
  )
),

flutter实现60s倒计时发送验证码功能。

Timer? timer;
String vcodeText = '获取验证码';
bool disabled = false;
int time = 60;

// 60s倒计时
void handleVcode() {
  if(authObj['tel'] == '') {
    snackbar('手机号不能为空');
  }else if(!Utils.checkTel(authObj['tel'])) {
    snackbar('手机号格式不正确');
  }else {
    setState(() {
      disabled = true;
    });
    startTimer();
  }
}
startTimer() {
  timer = Timer.periodic(const Duration(seconds: 1), (timer) {
    setState(() {
      if(time > 0) {
        vcodeText = '获取验证码(${time--})';
      }else {
        vcodeText = '获取验证码';
        time = 60;
        disabled = false;
        timer.cancel();
      }
    });
  });
  snackbar('短信验证码已发送，请注意查收', color: Colors.green);
}

Flutter3沉浸式渐变状态导航栏

要实现如上图渐变AppBar也非常简单，只需要配置AppBar提供的可伸缩灵活区域属性 flexibleSpace 配合gradient即可快速实现渐变导航栏。

AppBar(
  title: Text('Flutter3-Chat'),
  flexibleSpace: Container(
    decoration: const BoxDecoration(
      gradient: LinearGradient(
        begin: Alignment.topLeft,
        end: Alignment.bottomRight,
        colors: [
          Color(0xFF0091EA), Color(0xFF07C160)
        ],
      )
    ),
  )
),

Flutter3字体图标/自定义badge

flutter内置了丰富的字体图标，通过图标组件 Icon(Icons.add) 引入即可使用。

https://api.flutter-io.cn/flutter/material/Icons-class.html

另外还支持通过自定义IconData方式自定义图标，如使用阿里iconfont图表库图标。

Icon(IconData(0xe666, fontFamily: 'iconfont'), size: 18.0)

把下载的字体文件放到assets目录，

在pubspec.yaml中引入字体文件。

class FStyle {
  // 自定义iconfont图标
  static iconfont(int codePoint, {double size = 16.0, Color? color}) {
    return Icon(
      IconData(codePoint, fontFamily: 'iconfont', matchTextDirection: true),
      size: size,
      color: color,
    );
  }

  // 自定义Badge红点
  static badge(int count, {
    Color color = Colors.redAccent,
    bool isdot = false,
    double height = 18.0,
    double width = 18.0
  }) {
    final num = count > 99 ? '99+' : count;
    return Container(
      alignment: Alignment.center,
      height: isdot ? height / 2 : height,
      width: isdot ? width / 2 : width,
      decoration: BoxDecoration(color: color, borderRadius: BorderRadius.circular(100.00)),
      child: isdot ? null : Text('$num', style: const TextStyle(color: Colors.white, fontSize: 12.0)),
    );
  }
}

FStyle.badge(23)
FStyle.badge(2, color: Colors.pink, height: 10.0, width: 10.0)
FStyle.badge(0, isdot: true)

Flutter仿微信PopupMenu下拉菜单/下拉刷新

通过flutter提供的PopupMenuButton组件实现下拉菜单功能。

PopupMenuButton(
  icon: FStyle.iconfont(0xe62d, size: 17.0),
  offset: const Offset(0, 50.0),
  tooltip: '',
  color: const Color(0xFF353535),
  itemBuilder: (BuildContext context) {
    return <PopupMenuItem>[
      popupMenuItem(0xe666, '发起群聊', 0),
      popupMenuItem(0xe75c, '添加朋友', 1),
      popupMenuItem(0xe603, '扫一扫', 2),
      popupMenuItem(0xe6ab, '收付款', 3),
    ];
  },
  onSelected: (value) {
    switch(value) {
      case 0:
        print('发起群聊');
        break;
      case 1:
        Navigator.pushNamed(context, '/addfriends');
        break;
      case 2:
        print('扫一扫');
        break;
      case 3:
        print('收付款');
        break;
    }
  },
)

// 下拉菜单项
static popupMenuItem(int codePoint, String title, value) {
  return PopupMenuItem(
    value: value,
    child: Row(
      mainAxisAlignment: MainAxisAlignment.start,
      children: [
        const SizedBox(width: 10.0,),
        FStyle.iconfont(codePoint, size: 21.0, color: Colors.white),
        const SizedBox(width: 10.0,),
        Text(title, style: const TextStyle(fontSize: 16.0, color: Colors.white),),
      ],
    ),
  );
}

如上图：下拉刷新、上拉加载更多是通过 easy_refresh 组件实现功能。

EasyRefresh(
  // 下拉加载提示
  header: const ClassicHeader(
    // showMessage: false,
  ),
  // 加载更多提示
  footer: ClassicFooter(),
  // 下拉刷新逻辑
  onRefresh: () async {
    // ...下拉逻辑
    await Future.delayed(const Duration(seconds: 2));
  },
  // 上拉加载逻辑
  onLoad: () async {
    // ...
  },
  child: ListView.builder(
    itemCount: chatList.length,
    itemBuilder: (context, index) {
      return Ink(
        // ...
      );
    },
  ),
)

如上图：弹窗功能均是自定义AlertDialog实现效果。通过无限制容器UnconstrainedBox配合SizedBox组件实现自定义窗口大小。

// 关于弹窗
void aboutAlertDialog(BuildContext context) {
  showDialog(
    context: context,
    builder: (context) {
      return UnconstrainedBox(
        constrainedAxis: Axis.vertical,
        child: SizedBox(
          width: 320.0,
          child: AlertDialog(
            contentPadding: const EdgeInsets.symmetric(horizontal: 10.0, vertical: 20.0),
            backgroundColor: Colors.white,
            surfaceTintColor: Colors.white,
            shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12.0)),
            content: Padding(
              padding: const EdgeInsets.symmetric(horizontal: 10.0),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Image.asset('assets/images/logo.png', width: 90.0, height: 90.0, fit: BoxFit.cover,),
                  const SizedBox(height: 10.0),
                  const Text('Flutter3-WChat', style: TextStyle(color: Color(0xFF0091EA), fontSize: 22.0),),
                  const SizedBox(height: 5.0),
                  const Text('基于flutter3+dart3开发跨平台仿微信App聊天实例。', style: TextStyle(color: Colors.black45),),
                  const SizedBox(height: 20.0),
                  Text('©2024/01 Andy   Q: 282310962', style: TextStyle(color: Colors.grey[400], fontSize: 12.0),),
                ],
              ),
            ),
          ),
        ),
      );
    }
  );
}

// 二维码名片弹窗
void qrcodeAlertDialog(BuildContext context) {
  showDialog(
    context: context,
    builder: (context) {
      return UnconstrainedBox(
        constrainedAxis: Axis.vertical,
        child: SizedBox(
          width: 320.0,
          child: AlertDialog(
            contentPadding: const EdgeInsets.symmetric(horizontal: 10.0, vertical: 20.0),
            backgroundColor: const Color(0xFF07C160),
            surfaceTintColor: const Color(0xFF07C160),
            shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(3.0)),
            content: Padding(
              padding: const EdgeInsets.symmetric(horizontal: 10.0),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Image.asset('assets/images/qrcode.png', width: 250.0, fit: BoxFit.cover,),
                  const SizedBox(height: 15.0),
                  const Text('扫一扫，加我公众号', style: TextStyle(color: Colors.white60, fontSize: 14.0,),),
                ],
              ),
            ),
          ),
        ),
      );
    }
  );
}

// 退出登录弹窗
void logoutAlertDialog(BuildContext context) {
  showDialog(
    context: context,
    builder: (context) {
      return AlertDialog(
        content: const Text('确定要退出登录吗？', style: TextStyle(fontSize: 16.0),),
        backgroundColor: Colors.white,
        surfaceTintColor: Colors.white,
        shape: RoundedRectangleBorder(borderRadius: BorderRadius.circular(12.0)),
        elevation: 2.0,
        actionsPadding: const EdgeInsets.all(15.0),
        actions: [
          TextButton(
            onPressed: () {Navigator.of(context).pop();},
            child: const Text('取消', style: TextStyle(color: Colors.black54),)
          ),
          TextButton(
            onPressed: handleLogout,
            child: const Text('退出登录', style: TextStyle(color: Colors.red),)
          ),
        ],
      );
    }
  );
}

flutter实现微信朋友圈九宫格

GroupZone(images: item['images']),

GroupZone(
  images: uploadList,
  album: true,
  onChoose: () async {
    Toast.show('选择手机相册图片', duration: 2, gravity: 1);
  },
),

// 创建可点击预览图片
createImage(BuildContext context, String img, int key) {
  return GestureDetector(
    child: Hero(
      tag: img, // 放大缩小动画效果标识
      child: img == '+' ? 
      Container(color: Colors.transparent, child: const Icon(Icons.add, size: 30.0, color: Colors.black45),)
      :
      Image.asset(
        img,
        width: width,
        fit: BoxFit.contain,
      ),
    ),
    onTap: () {
      // 选择图片
      if(img == '+') {
        onChoose!();
      }else {
        Navigator.of(context).push(FadeRoute(route: ImageViewer(
          images: album ? imgList!.sublist(0, imgList!.length - 1) : imgList,
          index: key,
        )));
      }
    },
  );
}

使用photo_view插件实现预览大图功能，支持预览单张及多张大图。

import 'package:flutter/material.dart';
import 'package:photo_view/photo_view.dart';
import 'package:photo_view/photo_view_gallery.dart';

class ImageViewer extends StatefulWidget {
  const ImageViewer({
    super.key,
    this.images,
    this.index = 0,
  });

  final List? images; // 预览图列表
  final int index; // 当前预览图索引

  @override
  State<ImageViewer> createState() => _ImageViewerState();
}

class _ImageViewerState extends State<ImageViewer> {
  int currentIndex = 0;

  @override
  void initState() {
    super.initState();
    currentIndex = widget.index;
  }

  @override
  Widget build(BuildContext context) {
    var imgCount = widget.images?.length;

    return Scaffold(
      body: Stack(
        children: [
          Positioned(
            top: 0,
            left: 0,
            bottom: 0,
            right: 0,
            child: GestureDetector(
              child: imgCount == 1 ? PhotoView(
                imageProvider: AssetImage(widget.images![0]),
                backgroundDecoration: const BoxDecoration(
                  color: Colors.black,
                ),
                minScale: PhotoViewComputedScale.contained,
                maxScale: PhotoViewComputedScale.covered * 2,
                heroAttributes: PhotoViewHeroAttributes(tag: widget.images![0]),
                enableRotation: true,
              )
              :
              PhotoViewGallery.builder(
                itemCount: widget.images?.length,
                builder: (context, index) {
                  return PhotoViewGalleryPageOptions(
                    imageProvider: AssetImage(widget.images![index]),
                    minScale: PhotoViewComputedScale.contained,
                    maxScale: PhotoViewComputedScale.covered * 2,
                    heroAttributes: PhotoViewHeroAttributes(tag: widget.images![index]),
                  );
                },
                scrollPhysics: const BouncingScrollPhysics(),
                backgroundDecoration: const BoxDecoration(
                  color: Colors.black,
                ),
                pageController: PageController(initialPage: widget.index),
                enableRotation: true,
                onPageChanged: (index) {
                  setState(() {
                    currentIndex = index;
                  });
                },
              ),
              onTap: () {
                Navigator.of(context).pop();
              },
            ),
          ),
          // 图片索引index
          Positioned(
            top: MediaQuery.of(context).padding.top + 15,
            width: MediaQuery.of(context).size.width,
            child: Center(
              child: Visibility(
                visible: imgCount! > 1 ? true : false,
                child: Text('${currentIndex+1} / ${widget.images?.length}', style: const TextStyle(color: Colors.white)),
              )
            ),
          ),
        ],
      ),
    );
  }
}

flutter3聊天模块

文本框TextField设置maxLines: null即可实现多行文本输入，支持图文emoj混排，网址连接识别等功能。

// 输入框
Offstage(
  offstage: voiceBtnEnable,
  child: TextField(
    decoration: const InputDecoration(
      isDense: true,
      hoverColor: Colors.transparent,
      contentPadding: EdgeInsets.all(8.0),
      border: OutlineInputBorder(borderSide: BorderSide.none),
    ),
    style: const TextStyle(fontSize: 16.0,),
    maxLines: null,
    controller: editorController,
    focusNode: editorFocusNode,
    cursorColor: const Color(0xFF07C160),
    onChanged: (value) {},
  ),
),

支持仿微信语音按住说话，左滑取消发送、右滑转换语音功能。

// 语音
Offstage(
  offstage: !voiceBtnEnable,
  child: GestureDetector(
    child: Container(
      decoration: BoxDecoration(
        color: Colors.white,
        borderRadius: BorderRadius.circular(5),
      ),
      alignment: Alignment.center,
      height: 40.0,
      width: double.infinity,
      child: Text(voiceTypeMap[voiceType], style: const TextStyle(fontSize: 15.0),),
    ),
    onPanStart: (details) {
      setState(() {
        voiceType = 1;
        voicePanelEnable = true;
      });
    },
    onPanUpdate: (details) {
      Offset pos = details.globalPosition;
      double swipeY = MediaQuery.of(context).size.height - 120;
      double swipeX = MediaQuery.of(context).size.width / 2 + 50;
      setState(() {
        if(pos.dy >= swipeY) {
          voiceType = 1; // 松开发送
        }else if (pos.dy < swipeY && pos.dx < swipeX) {
          voiceType = 2; // 左滑松开取消
        }else if (pos.dy < swipeY && pos.dx >= swipeX) {
          voiceType = 3; // 右滑语音转文字
        }
      });
    },
    onPanEnd: (details) {
      // print('停止录音');
      setState(() {
        switch(voiceType) {
          case 1:
            Toast.show('发送录音文件', duration: 1, gravity: 1);
            voicePanelEnable = false;
            break;
          case 2:
            Toast.show('取消发送', duration: 1, gravity: 1);
            voicePanelEnable = false;
            break;
          case 3:
            Toast.show('语音转文字', duration: 1, gravity: 1);
            voicePanelEnable = true;
            voiceToTransfer = true;
            break;
        }
        voiceType = 0;
      });
    },
  ),
),

按住录音显示面板

// 录音主体(按住说话/松开取消/语音转文本)
Visibility(
  visible: voicePanelEnable,
  child: Material(
    color: const Color(0xDD1B1B1B),
    child: Stack(
      children: [
        // 取消发送+语音转文字
        Positioned(
          bottom: 120,
          left: 30,
          right: 30,
          child: Visibility(
            visible: !voiceToTransfer,
            child: Column(
              children: [
                // 语音动画层
                Stack(
                  children: [
                    Container(
                      height: 70.0,
                      margin: const EdgeInsets.symmetric(horizontal: 50.0),
                      decoration: BoxDecoration(
                        color: Colors.white,
                        borderRadius: BorderRadius.circular(15.0),
                      ),
                      child: Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Image.asset('assets/images/voice_record.gif', height: 30.0,)
                        ],
                      ),
                    ),
                    Positioned(
                      right: (MediaQuery.of(context).size.width - 60) / 2,
                      bottom: 1,
                      child: RotatedBox(
                        quarterTurns: 0,
                        child: CustomPaint(painter: ArrowShape(arrowColor: Colors.white, arrowSize: 10.0)),
                      )
                    ),
                  ],
                ),
                const SizedBox(height: 50.0,),
                // 操作项
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    // 取消发送
                    Container(
                      height: 60.0,
                      width: 60.0,
                      decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(50.0),
                        color: voiceType == 2 ? Colors.red : Colors.black38,
                      ),
                      child: const Icon(Icons.close, color: Colors.white54,),
                    ),
                    // 语音转文字
                    Container(
                      height: 60.0,
                      width: 60.0,
                      decoration: BoxDecoration(
                        borderRadius: BorderRadius.circular(50.0),
                        color: voiceType == 3 ? Colors.green : Colors.black38,
                      ),
                      child: const Icon(Icons.translate, color: Colors.white54,),
                    ),
                  ],
                ),
              ],
            ),
          ),
        ),
        // 语音转文字(识别结果状态)
        Positioned(
          bottom: 120,
          left: 30,
          right: 30,
          child: Visibility(
            visible: voiceToTransfer,
            child: Column(
              children: [
                // 提示结果
                Stack(
                  children: [
                    Container(
                      height: 100.0,
                      decoration: BoxDecoration(
                        color: Colors.red,
                        borderRadius: BorderRadius.circular(15.0),
                      ),
                      child: const Row(
                        mainAxisAlignment: MainAxisAlignment.center,
                        children: [
                          Icon(Icons.info, color: Colors.white,),
                          Text('未识别到文字。', style: TextStyle(color: Colors.white),),
                        ],
                      ),
                    ),
                    Positioned(
                      right: 35.0,
                      bottom: 1,
                      child: RotatedBox(
                        quarterTurns: 0,
                        child: CustomPaint(painter: ArrowShape(arrowColor: Colors.red, arrowSize: 10.0)),
                      )
                    ),
                  ],
                ),
                const SizedBox(height: 50.0,),
                // 操作项
                Row(
                  mainAxisAlignment: MainAxisAlignment.spaceBetween,
                  children: [
                    GestureDetector(
                      child: Container(
                        height: 60.0,
                        width: 60.0,
                        decoration: const BoxDecoration(
                          color: Colors.transparent,
                        ),
                        child: const Column(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            Icon(Icons.undo, color: Colors.white54,),
                            Text('取消', style: TextStyle(color: Colors.white70),)
                          ],
                        ),
                      ),
                      onTap: () {
                        setState(() {
                          voicePanelEnable = false;
                          voiceToTransfer = false;
                        });
                      },
                    ),
                    GestureDetector(
                      child: Container(
                        height: 60.0,
                        width: 100.0,
                        decoration: const BoxDecoration(
                          color: Colors.transparent,
                        ),
                        child: const Column(
                          mainAxisAlignment: MainAxisAlignment.center,
                          children: [
                            Icon(Icons.graphic_eq_rounded, color: Colors.white54,),
                            Text('发送原语音', style: TextStyle(color: Colors.white70),)
                          ],
                        ),
                      ),
                      onTap: () {},
                    ),
                    GestureDetector(
                      child: Container(
                        height: 60.0,
                        width: 60.0,
                        decoration: BoxDecoration(
                          borderRadius: BorderRadius.circular(50.0),
                          color: Colors.white12,
                        ),
                        child: const Icon(Icons.check, color: Colors.white12,),
                      ),
                      onTap: () {},
                    ),
                  ],
                ),
              ],
            ),
          ),
        ),
        // 提示文字(操作状态)
        Positioned(
          bottom: 120,
          left: 0,
          width: MediaQuery.of(context).size.width,
          child: Visibility(
            visible: !voiceToTransfer,
            child: Align(
              child: Text(voiceTypeMap[voiceType], style: const TextStyle(color: Colors.white70),),
            ),
          ),
        ),
        // 背景
        Align(
          alignment: Alignment.bottomCenter,
          child: Visibility(
            visible: !voiceToTransfer,
            child: Image.asset('assets/images/voice_record_bg.webp', width: double.infinity, height: 100.0, fit: BoxFit.fill),
          ),
        ),
        // 背景图标
        Positioned(
          bottom: 25,
          left: 0,
          width: MediaQuery.of(context).size.width,
          child: Visibility(
            visible: !voiceToTransfer,
            child: const Align(
              child: Icon(Icons.graphic_eq_rounded, color: Colors.black54,),
            ),
          ),
        ),
      ],
    ),
  ),
)

flutter3绘制箭头

聊天模块消息及各种箭头展示，通过flutter提供的画板功能绘制箭头。

// 绘制气泡箭头
class ArrowShape extends CustomPainter {
  ArrowShape({
    required this.arrowColor,
    this.arrowSize = 7,
  });

  final Color arrowColor; // 箭头颜色
  final double arrowSize; // 箭头大小

  @override
  void paint(Canvas canvas, Size size) {
    var paint = Paint()..color = arrowColor;

    var path = Path();
    path.lineTo(-arrowSize, 0);
    path.lineTo(0, arrowSize);
    path.lineTo(arrowSize, 0);
    canvas.drawPath(path, paint);
  }

  @override
  bool shouldRepaint(CustomPainter oldDelegate) {
    return false;
  }
}