flutter拍照、拍摄短视频、选择图片

1.添加依赖：image_picker

image_picker更多参考在https://pub.dev/packages/image_picker
在配置文件pubspec.yaml添加如下配置：

dependencies:
  flutter: sdk: flutter
  image_picker: ^0.6.7

2.开发拍照功能(完整例子)

在这里插入图片描述

import 'dart:convert';
import 'dart:io';
import 'dart:isolate';
import 'package:dio/dio.dart';
import 'package:flutter/cupertino.dart';
import 'package:flutter/foundation.dart';
import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';
import 'package:fluttertoast/fluttertoast.dart';
import 'package:video_player/video_player.dart';

void main() => runApp(DemoApp());

class DemoApp extends StatelessWidget {
  @override
  Widget build(BuildContext context) { return new MaterialApp( title: 'Image Picker Demo', home: new MyHomePage( title: "Image Picker Example", ), );
  }
}

class MyHomePage extends StatefulWidget {
  MyHomePage({Key key, this.title}) : super(key: key);
  final String title; @override
  _MyHomePageState createState() => _MyHomePageState();
}

class _MyHomePageState extends State<MyHomePage> {
  /// 图片选择器
  final ImagePicker _picker = ImagePicker(); /// 选择的图片
  PickedFile _imageFile; /// 是否是视频
  bool isVideo = false; /// 定义错误信息
  String _retrieveDataError; /// 选择图片时的错误信息
  dynamic _pickImageError; /// 视频播放器控制器
  VideoPlayerController _controller;
  VideoPlayerController _toBeDisposed; @override
  Widget build(BuildContext context) { return Scaffold( appBar: AppBar( title: Text(widget.title), ), body: Center( child: !kIsWeb && defaultTargetPlatform == TargetPlatform.android ? FutureBuilder( future: retrieveLostData(), builder: (BuildContext context, AsyncSnapshot<void> snapshot) { switch (snapshot.connectionState) { case ConnectionState.none: case ConnectionState.waiting: return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); case ConnectionState.done: return isVideo ? _previewVideo() : _previewImage(); default: if (snapshot.hasError) { return Text( "Pick image/video error:${snapshot.error}", textAlign: TextAlign.center, ); } else { return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); } } }) : (isVideo ? _previewVideo() : _previewImage())), floatingActionButton: Column( mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[ FloatingActionButton( onPressed: () { /// 选择图片 isVideo = false; _onImageButtonPressed(ImageSource.gallery, context: context); }, child: const Icon(Icons.photo_library), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { /// 拍照 isVideo = false; _onImageButtonPressed(ImageSource.camera, context: context); }, child: const Icon(Icons.camera_alt), ), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { // 选择视频文件 isVideo = true; _onImageButtonPressed(ImageSource.gallery); }, backgroundColor: Colors.red, child: const Icon(Icons.video_library), ), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { // 拍摄 isVideo = true; _onImageButtonPressed(ImageSource.camera); }, backgroundColor: Colors.red, child: const Icon(Icons.videocam), ), ), ], ), );
  } /// 获得丢失的数据
  Future<void> retrieveLostData() async { final LostData response = await _picker.getLostData(); if (response.isEmpty) { return; } if (response.file != null) { if (response.type == RetrieveType.video) { /// video isVideo = true; /// 播放视频 await _playVideo(response.file); } else { /// 图片 isVideo = false; setState(() { /// 更新UI，把图片显示出来 _imageFile = response.file; }); } } else { _retrieveDataError = response.exception.code; }
  } /// 播放视频
  Future<void> _playVideo(PickedFile file) async { /// mounted true 表示当前state仍然在widget tree上 if (file != null && mounted) { /// 重置视频播放器控制器 await _disposeVideoController(); if (kIsWeb) { /// kIsWeb true表示是web应用 _controller = VideoPlayerController.network(file.path); /// 设置音量为0 await _controller.setVolume(0.0); } else { /// 非web应用 _controller = VideoPlayerController.file(File(file.path)); /// 设置音量为1.0 await _controller.setVolume(1.0); } await _controller.initialize(); await _controller.setLooping(true); await _controller.play(); /// 更新UI setState(() {}); }
  } /// 重置视频播放器控制器
  Future<void> _disposeVideoController() async { if (_toBeDisposed != null) { await _toBeDisposed.dispose(); } _toBeDisposed = _controller; _controller = null;
  } Text _getRetrieveErrorWidget() { if (_retrieveDataError != null) { final Text result = Text(_retrieveDataError); _retrieveDataError = null; return result; } return null;
  } /// 预览视频
  Widget _previewVideo() { /// 获取错语信息 final Text retrieveError = _getRetrieveErrorWidget(); if (retrieveError != null) { /// 有错误信息则显示错误信息 return retrieveError; } if (_controller == null) { /// 如果视频播放器控制器为空，则提示用户选择视频 return const Text( "You have not yet picked a vide", textAlign: TextAlign.center, ); } return Padding( padding: const EdgeInsets.all(10.0), child: AspectRatioVideo(_controller), );
  } /// 预览图片
  Widget _previewImage() { /// 获取错语信息 final Text retrieveError = _getRetrieveErrorWidget(); if (retrieveError != null) { /// 有错误信息则显示错误信息 return retrieveError; } if (_imageFile != null) { if (kIsWeb) { /// web应用 return Image.network(_imageFile.path); } else { /// 非web应用 return Image.file(File(_imageFile.path)); } } else if (_pickImageError != null) { return Text( "Pick image error: $_pickImageError", textAlign: TextAlign.center, ); } else { return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); }
  } /// 选择图片、视频，拍摄视频、照片
  void _onImageButtonPressed(ImageSource source, {BuildContext context}) async { if (_controller != null) { /// 让其静音 await _controller.setVolume(0.0); } if (isVideo) { /// 选择或拍摄视频的处理 /// 限制视频为10秒 final PickedFile file = await _picker.getVideo( source: source, maxDuration: Duration(seconds: 10)); /// 返回到此界面时就播放 await _playVideo(file); } else { /// 选择或拍摄图片 /// 图片的参数设置对话框 await _displayPickImageDialog(context, (double maxWidth, double maxHeight, int quality) async { try { final pickedFile = await _picker.getImage( source: source, maxWidth: maxWidth, maxHeight: maxHeight, imageQuality: quality); setState(() { _imageFile = pickedFile; }); } catch (e) { _pickImageError = e; } }); }
  } final TextEditingController maxWidthController = TextEditingController();
  final TextEditingController maxHeightController = TextEditingController();
  final TextEditingController qualityController = TextEditingController(); /// 图片的参数设置对话框
  Future<void> _displayPickImageDialog( BuildContext context, OnPickImageCallback onPick) async { return showDialog( context: context, builder: (context) { return AlertDialog( title: Text("Add optional parameters"), content: Column( children: <Widget>[ TextField( controller: maxWidthController, keyboardType: TextInputType.numberWithOptions(decimal: true), decoration: InputDecoration(hintText: "Enter maxWidth if desired"), ), TextField( controller: maxHeightController, keyboardType: TextInputType.numberWithOptions(decimal: true), decoration: InputDecoration(hintText: "Enter maxHeight if desired"), ), TextField( controller: qualityController, keyboardType: TextInputType.number, decoration: InputDecoration(hintText: "Enter quality if desired"), ), ], ), actions: <Widget>[ FlatButton( onPressed: () { Navigator.of(context).pop(); }, child: Text("CANCEL"), ), FlatButton( onPressed: () { double width = maxWidthController.text.isNotEmpty ? double.parse(maxWidthController.text) : null; double height = maxHeightController.text.isNotEmpty ? double.parse(maxHeightController.text) : null; int quality = qualityController.text.isNotEmpty ? int.parse(qualityController.text) : null; onPick(width, height, quality); Navigator.of(context).pop(); }, child: Text("PICK"), ), ], ); }, );
  } @override
  void deactivate() { if (_controller != null) { _controller.setVolume(0.0); _controller.pause(); } super.deactivate();
  } @override
  void dispose() { _disposeVideoController(); maxWidthController.dispose(); maxHeightController.dispose(); qualityController.dispose(); super.dispose();
  }
}

typedef void OnPickImageCallback( double maxWidth, double maxHeight, int quality);

/// 自定义一个Widget，用于播放视频
class AspectRatioVideo extends StatefulWidget {
  AspectRatioVideo(this.controller); final VideoPlayerController controller; @override
  _AspectRatioVideoState createState() => _AspectRatioVideoState();
}

class _AspectRatioVideoState extends State<AspectRatioVideo> {
  /// 只读
  VideoPlayerController get controller => widget.controller;
  bool initialized = false; @override
  void initState() { super.initState(); controller.addListener(_onVideoControllerUpdate);
  } /// 更新
  void _onVideoControllerUpdate() { if (!mounted) { return; } if (initialized != controller.value.initialized) { initialized = controller.value.initialized; /// 更新UI setState(() {}); }
  } @override
  Widget build(BuildContext context) { if (initialized) { return Center( child: AspectRatio( child: VideoPlayer(controller), aspectRatio: controller.value?.aspectRatio, ), ); } else { return Container(); }
  } /// 关闭时，清理工作
  @override
  void dispose() { controller.removeListener(_onVideoControllerUpdate); super.dispose();
  }
}

2.1.屏幕主体

如果有图片显示，有视频则播放视频，否则提示用户选择图片：

body:Center( child: !kIsWeb && defaultTargetPlatform == TargetPlatform.android ? FutureBuilder( future: retrieveLostData(), builder: (BuildContext context, AsyncSnapshot<void> snapshot) { switch (snapshot.connectionState) { case ConnectionState.none: case ConnectionState.waiting: return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); case ConnectionState.done: return isVideo ? _previewVideo() : _previewImage(); default: if (snapshot.hasError) { return Text( "Pick image/video error:${snapshot.error}", textAlign: TextAlign.center, ); } else { return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); } } }) : (isVideo ? _previewVideo() : _previewImage())),

2.2.右下角四个按钮

floatingActionButton: Column( mainAxisAlignment: MainAxisAlignment.end, children: <Widget>[ FloatingActionButton( onPressed: () { /// 选择图片 isVideo = false; _onImageButtonPressed(ImageSource.gallery, context: context); }, child: const Icon(Icons.photo_library), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { /// 拍照 isVideo = false; _onImageButtonPressed(ImageSource.camera, context: context); }, child: const Icon(Icons.camera_alt), ), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { // 选择视频文件 isVideo = true; _onImageButtonPressed(ImageSource.gallery); }, backgroundColor: Colors.red, child: const Icon(Icons.video_library), ), ), Padding( padding: const EdgeInsets.only(top: 16.0), child: FloatingActionButton( onPressed: () { // 拍摄 isVideo = true; _onImageButtonPressed(ImageSource.camera); }, backgroundColor: Colors.red, child: const Icon(Icons.videocam), ), ), ], ),

2.3.每个按钮都触发一个事件

/// 选择图片、视频，拍摄视频、照片
  void _onImageButtonPressed(ImageSource source, {BuildContext context}) async { if (_controller != null) { /// 让其静音 await _controller.setVolume(0.0); } if (isVideo) { /// 选择或拍摄视频的处理 /// 限制视频为10秒 final PickedFile file = await _picker.getVideo( source: source, maxDuration: Duration(seconds: 10)); /// 返回到此界面时就播放 await _playVideo(file); } else { /// 选择或拍摄图片 /// 图片的参数设置对话框 await _displayPickImageDialog(context, (double maxWidth, double maxHeight, int quality) async { try { final pickedFile = await _picker.getImage( source: source, maxWidth: maxWidth, maxHeight: maxHeight, imageQuality: quality); setState(() { _imageFile = pickedFile; }); } catch (e) { _pickImageError = e; } }); }
  }

2.4.弹窗设置宽、高、质量

  final TextEditingController maxWidthController = TextEditingController();
  final TextEditingController maxHeightController = TextEditingController();
  final TextEditingController qualityController = TextEditingController(); /// 图片的参数设置对话框
  Future<void> _displayPickImageDialog( BuildContext context, OnPickImageCallback onPick) async { return showDialog( context: context, builder: (context) { return AlertDialog( title: Text("Add optional parameters"), content: Column( children: <Widget>[ TextField( controller: maxWidthController, keyboardType: TextInputType.numberWithOptions(decimal: true), decoration: InputDecoration(hintText: "Enter maxWidth if desired"), ), TextField( controller: maxHeightController, keyboardType: TextInputType.numberWithOptions(decimal: true), decoration: InputDecoration(hintText: "Enter maxHeight if desired"), ), TextField( controller: qualityController, keyboardType: TextInputType.number, decoration: InputDecoration(hintText: "Enter quality if desired"), ), ], ), actions: <Widget>[ FlatButton( onPressed: () { Navigator.of(context).pop(); }, child: Text("CANCEL"), ), FlatButton( onPressed: () { double width = maxWidthController.text.isNotEmpty ? double.parse(maxWidthController.text) : null; double height = maxHeightController.text.isNotEmpty ? double.parse(maxHeightController.text) : null; int quality = qualityController.text.isNotEmpty ? int.parse(qualityController.text) : null; onPick(width, height, quality); Navigator.of(context).pop(); }, child: Text("PICK"), ), ], ); }, );
  }

2.5.返回的结果是视频的话，就播放。

 /// 播放视频
  Future<void> _playVideo(PickedFile file) async { /// mounted true 表示当前state仍然在widget tree上 if (file != null && mounted) { /// 重置视频播放器控制器 await _disposeVideoController(); if (kIsWeb) { /// kIsWeb true表示是web应用 _controller = VideoPlayerController.network(file.path); /// 设置音量为0 await _controller.setVolume(0.0); } else { /// 非web应用 _controller = VideoPlayerController.file(File(file.path)); /// 设置音量为1.0 await _controller.setVolume(1.0); } await _controller.initialize(); await _controller.setLooping(true); await _controller.play(); /// 更新UI setState(() {}); }
  }

实际上，上面这个方法只是提前设置好视播放器控制器的信息，然后刷新UI，最终在build方法里通过_previewVideo来将视频显示出来：

  /// 预览视频
  Widget _previewVideo() { /// 获取错语信息 final Text retrieveError = _getRetrieveErrorWidget(); if (retrieveError != null) { /// 有错误信息则显示错误信息 return retrieveError; } if (_controller == null) { /// 如果视频播放器控制器为空，则提示用户选择视频 return const Text( "You have not yet picked a vide", textAlign: TextAlign.center, ); } return Padding( padding: const EdgeInsets.all(10.0), child: AspectRatioVideo(_controller), );
  }

为了显示视频，专门写了一个Widget控件AspectRatioVideo来显示：

/// 自定义一个Widget，用于播放视频
class AspectRatioVideo extends StatefulWidget {
  AspectRatioVideo(this.controller); final VideoPlayerController controller; @override
  _AspectRatioVideoState createState() => _AspectRatioVideoState();
}

class _AspectRatioVideoState extends State<AspectRatioVideo> {
  /// 只读
  VideoPlayerController get controller => widget.controller;
  bool initialized = false; @override
  void initState() { super.initState(); controller.addListener(_onVideoControllerUpdate);
  } /// 更新
  void _onVideoControllerUpdate() { if (!mounted) { return; } if (initialized != controller.value.initialized) { initialized = controller.value.initialized; /// 更新UI setState(() {}); }
  } @override
  Widget build(BuildContext context) { if (initialized) { return Center( child: AspectRatio( child: VideoPlayer(controller), aspectRatio: controller.value?.aspectRatio, ), ); } else { return Container(); }
  } /// 关闭时，清理工作
  @override
  void dispose() { controller.removeListener(_onVideoControllerUpdate); super.dispose();
  }
}

2.5.如果选择的是图片，则也是通过刷新UI，执行build方法来显示出来的，图片显示的方法：

  /// 预览图片
  Widget _previewImage() { /// 获取错语信息 final Text retrieveError = _getRetrieveErrorWidget(); if (retrieveError != null) { /// 有错误信息则显示错误信息 return retrieveError; } if (_imageFile != null) { if (kIsWeb) { /// web应用 return Image.network(_imageFile.path); } else { /// 非web应用 return Image.file(File(_imageFile.path)); } } else if (_pickImageError != null) { return Text( "Pick image error: $_pickImageError", textAlign: TextAlign.center, ); } else { return const Text( "You have not yet picked an image", textAlign: TextAlign.center, ); }
  }

3.总结

总的来说，使用flutter来写拍照、录视频等功能的体验真是太棒了！

文章来源: blog.csdn.net，作者：WongKyunban，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/weixin_40763897/article/details/108213854

（完）