wetterApp/lib/screens/rain_radar.dart

import 'dart:typed_data';
import 'package:flutter/material.dart';
import 'package:flutter_gifimage/flutter_gifimage.dart';
import 'package:flutter_cache_manager/flutter_cache_manager.dart';

class RainRadar extends StatefulWidget {
  const RainRadar({Key? key}) : super(key: key);

  @override
  State<RainRadar> createState() => _RainRadarState();
}

class _RainRadarState extends State<RainRadar>
    with SingleTickerProviderStateMixin<RainRadar> {
  late GifController controller;
  double controllerValue = 0;
  bool _gifLoaded = false;
  late Uint8List _gifBytes;

  @override
  void initState() {
    super.initState();
    loadGif();
    controller = GifController(vsync: this);
    controller.addListener(() {
      setState(() {
        controllerValue = controller.value;
      });
    });
    controller.stop();
  }

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

  void loadGif() async {
    imageCache.clear();
    await DefaultCacheManager()
        .getSingleFile('https://www.dwd.de/DWD/wetter/radar/radarvhs.gif')
        .then((gif) {
      setState(() {
        _gifBytes = gif.readAsBytesSync();
        _gifLoaded = true;
      });
      controller.animateTo(24, duration: const Duration(seconds: 15));
    });
  }

  Widget _showGif() {
    return Column(children: [
      Padding(
          padding: const EdgeInsets.all(10),
          child: _gifLoaded
              ? GifImage(controller: controller, image: MemoryImage(_gifBytes))
              : const CircularProgressIndicator()),
      Row(mainAxisAlignment: MainAxisAlignment.center, children: [
        ElevatedButton(
            onPressed: () {
              int duration = ((15 / 24) * (24 - controller.value)).round();
              controller.animateTo(24, duration: Duration(seconds: duration));
            },
            child: const Icon(Icons.play_arrow)),
        const SizedBox(width: 10),
        ElevatedButton(
            onPressed: () {
              controller.stop();
            },
            child: const Icon(Icons.pause)),
      ]),
      Slider(
        onChanged: (v) {
          controller.value = v;
          setState(() {});
        },
        max: 24,
        min: 0,
        value: controllerValue,
      )
    ]);
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
        appBar: AppBar(
          title: const Text('Rain Radar'),
        ),
        body: _gifLoaded
            ? _showGif()
            : Column(
                mainAxisAlignment: MainAxisAlignment.center,
                crossAxisAlignment: CrossAxisAlignment.center,
                children: const [
                    SizedBox(
                      height: 50,
                    ),
                    Center(child: CircularProgressIndicator())
                  ]));
  }
}