Flutter:在setState未显示更改后将小部件转换为图像

import 'package:flutter/material.dart';
import 'dart:ui' as ui;

class MyWidget extends StatefulWidget {
  @override
  _MyWidgetState createState() => _MyWidgetState();
}

class _MyWidgetState extends State<MyWidget> {
  GlobalKey globalKey = GlobalKey();

  @override
  Widget build(BuildContext context) {
    return RepaintBoundary(
      key: globalKey,
      child: Container(
        color: Colors.white,
        child: Center(
          child: RaisedButton(
            onPressed: () {
              setState(() {
                // 更新状态
              });
              WidgetsBinding.instance.addPostFrameCallback((_) {
                // 在帧绘制完成后将小部件转换为图像
                convertWidgetToImage();
              });
            },
            child: Text('Update State'),
          ),
        ),
      ),
    );
  }

  void convertWidgetToImage() async {
    RenderRepaintBoundary boundary =
        globalKey.currentContext.findRenderObject();
    ui.Image image = await boundary.toImage();
    // 在这里可以对图像进行进一步处理或保存
  }
}