问如何在颤动3秒后自动拍照？

EN

Timer(Duration(milliseconds: 3000), () {
    //after 3 seconds this will be called, 
    //once this is called take picture or whatever function you need to do
    takeScreenshot();
  });

takeScreenShot() async{
   RenderRepaintBoundary boundary = 
      previewContainer.currentContext.findRenderObject();
   ui.Image image = await boundary.toImage();
   final directory = (await getApplicationDocumentsDirectory()).path;
   ByteData byteData = await image.toByteData(format: ui.ImageByteFormat.png);
   Uint8List pngBytes = byteData.buffer.asUint8List();
   print(pngBytes);
   File imgFile =new File('$directory/screenshot.png');
   imgFile.writeAsBytes(pngBytes);
  }