为什么我在异步函数中使用 setState 而不是更新状态（Flutter）？

Question

为什么我的_image没有更新？

我需要 _image 当用户从图库或相机中选择新图像时更新属性，但是当用户选择新图像时，我使用 setState 将新值设置为 _image 但它没有用（没有更新 UI）。

这里我的代码有问题：抱歉，我无法获取完整源代码，因为 Whosebug 的编辑抱怨很多代码。

全状态 Class：枚举 ChooseMedia { 相机，画廊 }

  File _image;

  void getImage(ChooseMedia media) async {
    if (media == ChooseMedia.camera) {
      var image = await ImagePicker.pickImage(source: ImageSource.camera);
      var pathLocal = await getApplicationDocumentsDirectory();
      await image.copy('${pathLocal.path}/profileImage.jpg').then((_) {
        setState(() {
          _image = image;
        });
      });
    }
    if (ChooseMedia.gallery == media) {
      var image = await ImagePicker.pickImage(source: ImageSource.gallery);
      var pathLocal = await getApplicationDocumentsDirectory();

      await image.copy('${pathLocal.path}/profileImage.jpg').then((_) {
        setState(() {
          _image = image;
        });
      });
    }
  }



  @override
  Widget build(BuildContext context) {

        return PopupMenuButton(
          elevation: 5,
          shape: RoundedRectangleBorder(
              borderRadius: BorderRadius.all(Radius.circular(15))),
          onSelected: (ChooseMedia media) {
            getImage(media);
          },
          itemBuilder: (BuildContext context) => <PopupMenuEntry<ChooseMedia>>[
            const PopupMenuItem<ChooseMedia>(
              value: ChooseMedia.gallery,
              child: ListTile(
                leading: Icon(
                  Icons.picture_in_picture,
                ),
                title: Text('From galaxy'),
              ),
            ),
            const PopupMenuItem<ChooseMedia>(
              value: ChooseMedia.camera,
              child: ListTile(
                leading: Icon(Icons.camera),
                title: Text('Take picture'),
              ),
            ),
          ],
          child: Container(
              decoration: BoxDecoration(),
              padding: EdgeInsets.all(7),
              child: CircleAvatar(
                  backgroundImage: _image == null
                      ? AssetImage('assets/images/profile.jpg')
                      : FileImage(_image))),
        );
  }

Answer 1

您正在混合 'await' 和 'then' 就做

var copiedImage = await image.copy('${pathLocal.path}/profileImage.jpg');
setState(() {
    _image = copiedImage;
});

为什么我在异步函数中使用 setState 而不是更新状态（Flutter）？

Why I use setState in async funtion not update state (Flutter)?

setstate

dart

flutter