Flutter保存Widget为图片

dependencies:
  flutter:
    sdk: flutter
  flutter/rendering.dart:
  path_provider:

import 'dart:io';
import 'dart:typed_data';
import 'package:flutter/rendering.dart';
import 'package:path_provider/path_provider.dart';
import 'package:flutter/services.dart';

GlobalKey widgetKey = GlobalKey();

Future<Uint8List> captureWidgetToImage() async {
  try {
    RenderRepaintBoundary boundary =
        widgetKey.currentContext.findRenderObject() as RenderRepaintBoundary;
    ui.Image image = await boundary.toImage(pixelRatio: 2.0);
    ByteData byteData =
        await image.toByteData(format: ui.ImageByteFormat.png);
    Uint8List pngBytes = byteData.buffer.asUint8List();
    return pngBytes;
  } catch (e) {
    print(e);
    return null;
  }
}

Uint8List imageBytes = await captureWidgetToImage();
final directory = await getTemporaryDirectory();
final imagePath = '${directory.path}/widget_image.png';
File imageFile = File(imagePath);
imageFile.writeAsBytesSync(imageBytes);