[移动开发]Flutter 显式动画 AnimatedModalBarrier 源代码 颜色的变化

Flutter 显式动画 AnimatedModalBarrier 源代码

https://www.woolha.com/tutorials/flutter-using-animatedmodalbarrier-examples?

import 'dart:async';

import 'package:flutter/material.dart';

class AnimatedModalBarrierDemo extends StatefulWidget {
  @override
  State<StatefulWidget> createState() {
    return _AnimatedModalBarrierDemoState();
  }
}

class _AnimatedModalBarrierDemoState extends State<AnimatedModalBarrierDemo>
    with SingleTickerProviderStateMixin {
  bool _isLoading = false;

  late Widget _modalBarrier;

  late AnimationController _controller;

  late Animation<Color?> _colorTweenAnimation;

  @override
  void initState() {
    ColorTween _colorTween = ColorTween(
      begin: Color.fromARGB(100, 255, 255, 255),
      end: Color.fromARGB(100, 127, 127, 127),
    );

    _controller =
        AnimationController(vsync: this, duration: const Duration(seconds: 3));

    _colorTweenAnimation = _colorTween.animate(_controller);

    _modalBarrier = AnimatedModalBarrier(
      color: _colorTweenAnimation,
      dismissible: true,
    );

    super.initState();
  }

  List<Widget> buildWidgetList(BuildContext context) {
    List<Widget> widgets = <Widget>[
      ElevatedButton(
        child: Text('Button'),
        onPressed: () {
          setState(() {
            _isLoading = true;
          });

          _controller.reset();

          _controller.forward();

          ScaffoldMessenger.of(context).showSnackBar(
            const SnackBar(
              content: Text('A SnackBar has been shown.'),
            ),
          );

          Future.delayed(const Duration(seconds: 5), () {
            setState(() {
              _isLoading = false;
            });
          });
        },
      ),
    ];

    if (_isLoading) {
      widgets.add(_modalBarrier);
    }

    return widgets;
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text('Woolha.com Flutter Tutorial'),
      ),
      body: Builder(
        builder: (context) => Center(
          child: Padding(
            padding: EdgeInsets.all(15.0),
            child: Column(
              mainAxisAlignment: MainAxisAlignment.center,
              children: <Widget>[
                Container(
                  height: 100.0,

                  width: 250.0,

                  // alignment: FractionalOffset.center,

                  child: new Stack(
                    alignment: AlignmentDirectional.center,
                    children: buildWidgetList(context),
                  ),
                ),
              ],
            ),
          ),
        ),
      ),
    );
  }
}