您可能想看看flutter的screenshot包。

一个简单的包捕获小部件作为图像。现在你也可以捕获小部件，而不是呈现在屏幕上!

1.创建截图控制器示例

class _MyHomePageState extends State<MyHomePage> {
  int _counter = 0;
  Uint8List _imageFile;

  //Create an instance of ScreenshotController
  ScreenshotController screenshotController = ScreenshotController(); 

  @override
  void initState() {
    // TODO: implement initState
    super.initState();
  }
  ...
}

2.将您要捕获的小部件 Package 在ScreenshotWidget中。将控制器分配给您之前创建的screenshotController

Screenshot(
    controller: screenshotController,
    child: Text("This text will be captured as image"),
),

3、调用capture方法截图，返回Uint8List

screenshotController.capture().then((Uint8List image) {
    //Capture Done
    setState(() {
        _imageFile = image;
    });
}).catchError((onError) {
    print(onError);
});

额外：将图像保存到特定位置

final directory = (await getApplicationDocumentsDirectory ()).path; //from path_provide package
String fileName = DateTime.now().microsecondsSinceEpoch;
path = '$directory';

screenshotController.captureAndSave(
    path //set path where screenshot will be saved
    fileName:fileName 
);

参考this示例

我曾经在一个应用程序中工作，我需要类似的东西。搜索了一段时间后，我发现了一个名为“screenshot”的包
这个包可以让你把可见或不可见的小部件转换成图像。
下面是他们文档中的示例代码

ScreenshotController screenshotController = ScreenshotController();

  function createScreenshot(){
     screenshotController
       .captureFromWidget(Container(
         padding: const EdgeInsets.all(30.0),
         decoration: BoxDecoration(
           border: Border.all(color: Colors.blueAccent, width: 5.0),
           color: Colors.redAccent,
         ),
         child: Text("This is an invisible widget"),
       ),
     ).then((capturedImage) {
       // Here you will get image object
     });
  }