如何在同一个GestureDetector中使用垂直和水平拖动和缩放？

import 'package:flutter/material.dart';

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

class _MyWidgetState extends State<MyWidget> {
  double startScale;
  Offset startPosition;

  @override
  Widget build(BuildContext context) {
    return GestureDetector(
      onScaleStart: (details) {
        startScale = details.scale;
      },
      onScaleUpdate: (details) {
        double newScale = startScale * details.scale;
        // 将新的缩放比例应用到元素上
        // ...
      },
      onScaleEnd: (details) {
        startScale = null;
      },
      onPanStart: (details) {
        startPosition = details.globalPosition;
      },
      onPanUpdate: (details) {
        Offset delta = details.globalPosition - startPosition;
        // 将平移的距离应用到元素上
        // ...
      },
      onPanEnd: (details) {
        startPosition = null;
      },
      child: Container(
        // 要进行操作的元素
      ),
    );
  }
}