location2025/lib/widget/animated_visibility.dart

import 'package:flutter/material.dart';

class AnimatedVisibility extends StatefulWidget {
  final bool visible;
  final Widget child;
  final Duration duration;
  final Curve curve;

  const AnimatedVisibility({
    super.key,
    required this.visible,
    required this.child,
    this.duration = const Duration(milliseconds: 400),
    this.curve = Curves.easeInOut,
  });

  @override
  State<AnimatedVisibility> createState() => _AnimatedVisibilityState();
}

class _AnimatedVisibilityState extends State<AnimatedVisibility>
    with SingleTickerProviderStateMixin {
  late final AnimationController _controller;
  late final Animation<double> _fadeAnimation;

  @override
  void initState() {
    super.initState();
    _controller = AnimationController(
      duration: widget.duration,
      vsync: this,
    );
    _fadeAnimation = CurvedAnimation(parent: _controller, curve: widget.curve);

    if (widget.visible) {
      _controller.forward();
    }
  }

  @override
  void didUpdateWidget(covariant AnimatedVisibility oldWidget) {
    super.didUpdateWidget(oldWidget);
    if (widget.visible != oldWidget.visible) {
      widget.visible ? _controller.forward() : _controller.reverse();
    }
  }

  @override
  void dispose() {
    _controller.dispose();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    return SizeTransition(
      sizeFactor: _fadeAnimation,
      axisAlignment: -1.0, // 从上方展开
      child: FadeTransition(
        opacity: _fadeAnimation,
        child: widget.child,
      ),
    );
  }
}