flutter 相冊和攝像頭（軟硬交互調自身系統）image_picker

首先必須注意一點：在升級flutter1.9+之后,flutter默認的iOS項目為swift,Android的默認項目為kotlin,而且通過IDEA創建的flutter項目,即使勾選了語言為oc,但是創建后的項目仍然是swift,頗為頭疼.這里我們講解的是基於iOS的OC和Android的JAVA來做的，畢竟我還是水手還沒上岸成為干貨（功力不足）。總之先跑通，再深究。

 

image_picker使用方法

首先添加依賴

在pubspec.yaml加入image_picker的依賴，版本號在github上找最新的即可。

如下：最新的是可以在這里找到：https://pub.dev/flutter/packages?q=image_picker，輸入：image_picker即可搜索到最新版本，這里用老版本（穩）

 

 依賴添加完成點擊右上角的 Packages get 出現finished及可。

 

使用
依賴添加完成之后我們就可以正常使用了

是不是超級簡單，我們權限申請都不需要管。

下面是完整代碼：

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart'; //在pubspec.yaml加入image_picker的依賴,image_picker: ^0.5.0+3

void main() {
  runApp( MaterialApp(
    title: 'Flutter gesture',
//    home: TutorialHome(),
    home: AuthenticationId(),
  ));
}


class AuthenticationId extends StatefulWidget {
  @override
  _AuthenticationIdState createState() => _AuthenticationIdState();
}
class _AuthenticationIdState extends State<AuthenticationId>{
  var imgPath;
  /*拍照*/
  takePhoto() async {
    var image = await ImagePicker.pickImage(source: ImageSource.camera);

    setState(() {
      imgPath = image;
    });
  }
  /*相冊*/
  openGallery() async {
    var image = await ImagePicker.pickImage(source: ImageSource.gallery);
    setState(() {
      imgPath = image;
    });
  }
  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: Text("認證"),
          elevation: 0.0,
        ),
        body: SingleChildScrollView(
          child: Column(
            mainAxisAlignment: MainAxisAlignment.center,
            children: <Widget>[
              Container(
                child: imgPath == null ? Text('請選擇拍照'):Image.file(imgPath),
              ),
              RaisedButton(
                onPressed: takePhoto,
                child: Text("拍照"),
              ),
              RaisedButton(
                onPressed: openGallery,
                child: Text("選擇照片"),
              ),
            ],
          ),
        ));
  }
}

 

注意事項
當圖片過長超過顯示寬高度的話，可能會報 The overflowing RenderFlex has an orientation of Axis.vertical. 這個錯，且底部會有黃色的警告。
具體報錯信息大概如下：

══╡ EXCEPTION CAUGHT BY RENDERING LIBRARY ╞═════════════════════════════════════════════════════════
I/flutter (10595): The following message was thrown during layout:
I/flutter (10595): A RenderFlex overflowed by 177 pixels on the bottom.
I/flutter (10595):
I/flutter (10595): The overflowing RenderFlex has an orientation of Axis.vertical.
I/flutter (10595): The edge of the RenderFlex that is overflowing has been marked in the rendering with a yellow and
I/flutter (10595): black striped pattern. This is usually caused by the contents being too big for the RenderFlex.
I/flutter (10595): Consider applying a flex factor (e.g. using an Expanded widget) to force the children of the
I/flutter (10595): RenderFlex to fit within the available space instead of being sized to their natural size.
I/flutter (10595): This is considered an error condition because it indicates that there is content that cannot be
I/flutter (10595): seen. If the content is legitimately bigger than the available space, consider clipping it with a
I/flutter (10595): ClipRect widget before putting it in the flex, or using a scrollable container rather than a Flex,
I/flutter (10595): like a ListView.

這里我們直接使用 SingleChildScrollView（單個子控件的滾動布局控件） 即可。

原文不足的地方我這里（上面）已經補全了。
原文出處：https://blog.csdn.net/yuzhiqiang_1993/article/details/88345232（）