您可以通过创建自己的ImplicitlyAnimatedWidget来实现这一点。
由于参数AlignmentGeometry包含lerp的静态方法，AnimatedContainer可以使用指定的visitor函数来评估此状态控制的每个tween的值。因此，简而言之，您还需要为TextAlign的静态方法添加一个扩展。
这可能需要做很多工作，但对我来说，你可以使用AnimatedContainer中现有的AlignmentGeometry属性，然后创建一个自定义扩展，将TextAlign的值转换为AlignGeometry的值。
范例：

extension TextAlignX on TextAlign {
  /// Converts this [TextAlign] to [AlignmentGeometry].
  AlignmentGeometry get toAlignGeometry {
    switch (this) {
      case TextAlign.left:
        return Alignment.centerLeft;
      case TextAlign.right:
        return Alignment.centerRight;
      case TextAlign.center:
        return Alignment.center;
      default:
        return Alignment.centerLeft;
    }
  }
}

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验证码：

import 'dart:math';

import 'package:flutter/material.dart';

void main() {
  runApp(const MyApp());
}

class MyApp extends StatelessWidget {
  const MyApp({super.key});

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      title: 'Flutter Demo',
      theme: ThemeData(
        primarySwatch: Colors.blue,
      ),
      home: const MyHomePage(title: 'Flutter Demo Home Page'),
    );
  }
}

class MyHomePage extends StatefulWidget {
  const MyHomePage({super.key, required this.title});

  final String title;

  @override
  State<MyHomePage> createState() => _MyHomePageState();
}

extension TextAlignX on TextAlign {
  /// Converts this [TextAlign] to [AlignmentGeometry].
  AlignmentGeometry get toAlignGeometry {
    switch (this) {
      case TextAlign.left:
        return Alignment.centerLeft;
      case TextAlign.right:
        return Alignment.centerRight;
      case TextAlign.center:
        return Alignment.center;
      default:
        return Alignment.centerLeft;
    }
  }
}

class _MyHomePageState extends State<MyHomePage> {
  Color color = Colors.black;
  TextAlign align = TextAlign.end;

  void _incrementCounter() {
    setState(() {
      color = Colors.red;
      // Just to change the alignment randomly.
      align = TextAlign.values[Random().nextInt(4)];
    });
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(widget.title),
      ),
      body: Center(
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          children: <Widget>[
            AnimatedContainer(
              width: 200,
              height: 200,
              color: Colors.yellow.withOpacity(0.5),
              alignment: align.toAlignGeometry,
              duration: const Duration(milliseconds: 500),
              child: AnimatedDefaultTextStyle(
                style: TextStyle(
                  color: color,
                  fontSize: 15,
                ),
                textAlign: TextAlign.center,
                duration: const Duration(milliseconds: 500),
                child: const Text('Animated Text Align'),
              ),
            )
          ],
        ),
      ),
      floatingActionButton: FloatingActionButton(
        onPressed: _incrementCounter,
        tooltip: 'Increment',
        child: const Icon(Icons.add),
      ),
    );
  }
}

型