[移动开发]Flutter之图片选择器image_picker

前言：image_picker可以camera拍照，也可以从gallery相册中选择。
1.导入库：image_picker: ^0.7.4
2.demo：

class MyIndexedStack extends StatefulWidget{
  @override
  State<StatefulWidget> createState() {
    return _MyIndexedStack();
  }
}
class _MyIndexedStack extends State<MyIndexedStack>{
  int _pageIndex = 0;
  final ImagePicker picker = new ImagePicker();
  String str11 = "http://pic1.win4000.com/pic/2/4e/f0a80319bd.jpg";
  var str1 ;
  String str22 = "http://pic1.win4000.com/pic/d/dc/95bb6142d5_250_350.jpg";
  var str2  ;
  @override
  Widget build(BuildContext context) {
        return MaterialApp(
          debugShowCheckedModeBanner: false,
          home: Scaffold(
            body: IndexedStack(
              children: [
                str1==null?Image.network(str11):Image.file(File(str1),fit: BoxFit.fill,),
                str2==null?Image.asset('assets/images/person_top_bg.jpg'):Image.file(File(str2),fit: BoxFit.fill,),
              ],
              index: _pageIndex,
            ),
            floatingActionButton: FloatingActionButton(
              onPressed: (){
                _pageIndex = _pageIndex==0?1:0;
                if(_pageIndex==1){
                  _getCameraImage();
                }else{
                  _getGalleryImage();
                }
                setState(() {

                });
              },
              child: Icon(Icons.add),
            ),
          )

        );
  }
  //进入系统相机拍照，str1就是拍的图片的路径
  Future _getCameraImage() async{
     final cameraImages = await picker.getImage(source: ImageSource.camera);
     if(mounted){
       setState(() {
         if(cameraImages!=null){
           str1 = cameraImages.path;
           print('camera路径为:${cameraImages.path}');
         }
       });
     }
  }
  //进入系统相册，str2就是选择的图片的地址
  Future _getGalleryImage() async{
    final galleryImages = await picker.getImage(source: ImageSource.gallery);
    if(mounted){
      setState(() {
        if(galleryImages!=null){
          str2 = galleryImages.path;
          print('gallery路径为:${galleryImages.path}');
        }
      });
    }
  }
}

//从网络上读取
Image.network(str11):Image.file(File(str1),fit: BoxFit.fill,)
//从本地应用内读取
Image.asset(‘assets/images/person_top_bg.jpg’)
//从手机内存中读取
Image.file(File(str2),fit: BoxFit.fill,)