尝试从图库中选择图像并使用相机抖动拍摄图像时出现 setState() 或 markNeedsBuild() 错误

Question

我正在尝试从我的图库中拍摄图像或立即使用相机拍摄上传页面。我创建了一个对话框来显示这两个选项，但出现错误

在构建期间调用 setState() 或 markNeedsBuild()。

当我在我的模拟器上运行时。
任何帮助将不胜感激。谢谢

这是我的代码

import 'package:flutter/material.dart';
import 'package:image_picker/image_picker.dart';


class UploadPage extends StatefulWidget {
  @override
  _UploadPageState createState() => _UploadPageState();
}

class _UploadPageState extends State<UploadPage> {
 PickedFile image;
 final picker=ImagePicker();

  takeImage(mContext){
    return showDialog(
      context: mContext,
      builder: (context){
        return SimpleDialog(
          title: Text("New post"),
          children: [
            SimpleDialogOption(
              child: Text("Upload from from gallery"),
              onPressed: ()async{
                Navigator.pop(context);
                final file=await picker.getImage(
                  source: ImageSource.gallery,
                //  maxHeight: 600,
                //  maxWidth: 970,
                );
                setState(() {
                  this.image=file;
                });
              },
            ),
            SimpleDialogOption(
              child: Text("Capture with camera"),
              onPressed: ()async{
               Navigator.pop(context);
               final file=await picker.getImage(
                 source: ImageSource.camera,
                 maxHeight: 600,
                 maxWidth: 970,
               );
               setState(() {
                 this.image=file;
               });
              },
            ),
            SimpleDialogOption(
              child: Text("Cancel",style: TextStyle(color: Colors.red),),
              onPressed: (){
                Navigator.pop(context);
              },
            ),
          ],
        );
      }
    );
  }
  @override
  Widget build(BuildContext context) {
    return takeImage(context);

  }
}

Answer 1

showDialog 在应用的当前内容上方显示一个对话框并返回未来。

构建后可以调用showDialog

class UploadPage extends StatefulWidget {
  @override
  _UploadPageState createState() => _UploadPageState();
}

class _UploadPageState extends State<UploadPage> {
  PickedFile image;
  final picker = ImagePicker();

  takeImage(mContext) {
    return showDialog(
        context: mContext,
        builder: (context) {
          return SimpleDialog(
            title: Text("New post"),
            children: [
              SimpleDialogOption(
                child: Text("Upload from from gallery"),
                onPressed: () async {
                  Navigator.pop(context);
                  final file = await picker.getImage(
                    source: ImageSource.gallery,
                    //  maxHeight: 600,
                    //  maxWidth: 970,
                  );
                  setState(() {
                    this.image = file;
                  });
                },
              ),
              SimpleDialogOption(
                child: Text("Capture with camera"),
                onPressed: () async {
                  Navigator.pop(context);
                  final file = await picker.getImage(
                    source: ImageSource.camera,
                    maxHeight: 600,
                    maxWidth: 970,
                  );
                  setState(() {
                    this.image = file;
                  });
                },
              ),
              SimpleDialogOption(
                child: Text(
                  "Cancel",
                  style: TextStyle(color: Colors.red),
                ),
                onPressed: () {
                  Navigator.pop(context);
                },
              ),
            ],
          );
        });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(
          'Take Picture',
        ),
      ),
      body: Center(
        child: FlatButton(
          color: Colors.blue,
          onPressed: () {
            takeImage(context);
          },
          child: Text(
            'Select Image',
            style: TextStyle(color: Colors.white),
          ),
        ),
      ),
    );
  }
}