带有 SlideTransition 的 Flutter AnimatedSwitcher

Question

在这段代码中，我尝试用

SlideTransition

做一个简单的递增数字，但它不能正常工作，我只能使用

ScaleTransition

成功。这意味着我想用

SlideTransition

增加数量

class TestScreen extends StatefulWidget {
  const TestScreen({super.key});

  @override
  State<TestScreen> createState() => _TestScreenState();
}

class _TestScreenState extends State<TestScreen> with SingleTickerProviderStateMixin {
  int num = 0;
  late final AnimationController _animationController = AnimationController(
      duration: Duration(milliseconds: 750),
      vsync: this)
    ..forward();

  static final offset1 = Tween<Offset>(begin: Offset.zero, end: Offset(0, -1));
  @override
  void initState() {
    super.initState();
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      backgroundColor: Colors.white,
      body: Container(
        width: double.infinity,
        height: double.infinity,
        child: Column(
          mainAxisAlignment: MainAxisAlignment.center,
          crossAxisAlignment: CrossAxisAlignment.center,
          children: [
            AnimatedSwitcher(
              duration: Duration(milliseconds: 1000),
              transitionBuilder: (child, animation) => SlideTransition(
                position: (offset1).animate(animation),
                child: child,
              ),
              child: Text(
                key: ValueKey(num),
                '$num',
                style: TextStyle(color: Colors.black, fontSize: 64.0),
              ),
            ),
            ElevatedButton(
              onPressed: () {
                setState(() {
                  num++;
                });
              },
              child: Text('increment'),
            ),
          ],
        ),
      ),
    );
  }
}