```   return Dialog(
      backgroundColor: Colors.white,
      shape: RoundedRectangleBorder(
          borderRadius: BorderRadius.all(Radius.circular(16.0))),
      child: Container(
        padding: EdgeInsets.all(16.0),
        child: Stack(
          children: <Widget>[
            Container(
              foregroundDecoration: _loading
                  ? BoxDecoration(
                      color: Colors.white.withOpacity(0.5),
                    )
                  : null,
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: <Widget>[
                  TextField(
                    controller: _controller,
                    decoration: InputDecoration(
                      border: OutlineInputBorder(),
                      labelText: 'New assignment',
                      labelStyle: TextStyle(
                        fontSize: 16.0,
                        fontWeight: FontWeight.w500,
                      ),
                      errorText: _valid ? null : 'Name your assignment first',
                      errorStyle: TextStyle(
                        fontSize: 12.0,
                        fontWeight: FontWeight.w500,
                      ),
                    ),
                    autocorrect: true,
                    autofocus: true,
                    textCapitalization: TextCapitalization.words,
                  ),
                  SizedBox(height: 10.0),
                  Row(
                    children: <Widget>[
                      DialogButton(
                        icon: Icons.camera,
                        onTap: () async {
                          if (_controller.text.isEmpty) {
                            return setState(() {
                              _valid = false;
                            });
                          }
                          final cameras = await availableCameras();
                          Navigator.of(context).push(MaterialPageRoute(
                              builder: (context) => CameraScreen(
                                    onTaken: uploadFile,
                                    camera: cameras.first,
                                  )));
                        },
                        label: 'Take a photo',
                      ),
                      SizedBox(width: 10.0),
                      DialogButton(
                        icon: Icons.insert_drive_file,
                        onTap: () async {
                          if (_controller.text.isEmpty) {
                            return setState(() {
                              _valid = false;
                            });
                          }
                          File file = await FilePicker.getFile();
                          uploadFile(file);
                        },
                        label: 'Upload a file',
                      ),
                    ],
                  ),
                ],
              ),
            ),
            _loading
                ? Center(
                    child: CircularProgressIndicator(),
                  )
                : Container(height: 0.0, width: 0.0),
          ],
        ),
      ),
    );
```