使用navigator.pop从签名返回图像

Question

我正在为签名图像编写代码。但是当我使用包flutter_signature_pad并返回结果时，结果只是空白屏幕。

我曾尝试使用navigator.pop和Setinitstate这样的代码。

FirstScreen

_navigateAndDisplaySelection(BuildContext context) async {
    final result = await Navigator.push(
      context,
      MaterialPageRoute(builder: (context) => SignApp()),
    );
    setState(() {
      _imageFile = result;
    });
  }

   Container(
          width: double.infinity,
          height: 150.0,
          child: InkWell(
            onTap: (){
              _navigateAndDisplaySelection(context);
            },
            child: _imageFile == null ? Image.network(BaseURL.folderUpload + widget.model.image)
            : Image.file(
              _imageFile, 
            fit: BoxFit.fill,
            ),
          ),
        ),

当我致电nvaigator.pop时此代码

MaterialButton(
                      color: Colors.green,
                      onPressed: () async {
                        final sign = _sign.currentState;
                        //retrieve image data, do whatever you want with it (send to server, save locally...)
                        final image = await sign.getData();
                        var data = await image.toByteData(format: ui.ImageByteFormat.png);
                        sign.clear();
                        final encoded = base64.encode(data.buffer.asUint8List());
                        var data2 = data.buffer.asUint8List();
                        Navigator.pop(context, data2);
                        debugPrint("onPressed " + encoded);
                      },
                      child: Text("Save")),

我要在绘制签名后，将结果图像返回到firstscreen并声明为_imageFile。