Progress Popup Widget with Stream

main.dart

import 'dart:async';
import 'package:flutter/material.dart';
//Progress Popup Widget with Stream

/// Beispiel-Datenmodell, das vom Stream gesendet wird.
class MyStreamData {
  final double progress; // 0.0 .. 1.0
  final String? message;
  final bool done;

  MyStreamData({required this.progress, this.message, this.done = false});
}

/// Kommunikation-Klasse, die einen Stream erzeugt.
/// In der Praxis kommt der Stream z.B. von WebSocket, Isolate, HTTP-Upload-Progress etc.
class MyCommunication {
  final StreamController<MyStreamData> _controller = StreamController.broadcast();

  Stream<MyStreamData> get incomingStream => _controller.stream;

  /// Beispiel: startet eine simulierte Progress-Übertragung
  void startSimulatedTransfer({Duration step = const Duration(milliseconds: 300)}) {
    double p = 0.0;
    Timer.periodic(step, (t) {
      p += 0.05;
      if (p >= 1.0) {
        _controller.add(MyStreamData(progress: 1.0, message: 'Fertig', done: true));
        t.cancel();
        return;
      }
      _controller.add(MyStreamData(progress: p, message: 'Lade ${ (p*100).round() }%'));
    });
  }

  void dispose() {
    _controller.close();
  }
}

/// PopupMessage Widget zeigt eine simple Card mit ProgressBar und Text.
/// Es verwaltet eine StreamSubscription<MyStreamData> und aktualisiert State.
class PopupMessage extends StatefulWidget {
  final Stream<MyStreamData> stream;
  final VoidCallback? onDone;

  const PopupMessage({Key? key, required this.stream, this.onDone}) : super(key: key);

  @override
  State<PopupMessage> createState() => _PopupMessageState();
}

class _PopupMessageState extends State<PopupMessage> {
  late StreamSubscription<MyStreamData> _sub;
  double _progress = 0.0;
  String _text = 'Warte...';
  bool _visible = true;

  @override
  void initState() {
    super.initState();
    _sub = widget.stream.listen((data) {
      // Aktualisiere UI bei neuen Daten
      setState(() {
        _progress = data.progress.clamp(0.0, 1.0);
        if (data.message != null) _text = data.message!;
        if (data.done) {
          _visible = false;
        }
      });

      // optional: Callback informieren
      if (data.done) widget.onDone?.call();
    }, onError: (e) {
      setState(() {
        _text = 'Fehler: $e';
        _visible = false;
      });
    }, onDone: () {
      setState(() {
        _visible = false;
      });
    });
  }

  @override
  void dispose() {
    _sub.cancel();
    super.dispose();
  }

  @override
  Widget build(BuildContext context) {
    if (!_visible) return const SizedBox.shrink();

    return Center(
      child: Material(
        color: Colors.transparent,
        child: Card(
          elevation: 8,
          child: SizedBox(
            width: 300,
            child: Padding(
              padding: const EdgeInsets.all(16.0),
              child: Column(
                mainAxisSize: MainAxisSize.min,
                children: [
                  Text(_text),
                  const SizedBox(height: 12),
                  LinearProgressIndicator(value: _progress),
                  const SizedBox(height: 12),
                  Row(
                    mainAxisAlignment: MainAxisAlignment.end,
                    children: [
                      Text('${(_progress * 100).round()}%'),
                    ],
                  ),
                ],
              ),
            ),
          ),
        ),
      ),
    );
  }
}

/// Minimaler demo App, die PopupMessage in einem Stack zeigt.
class DemoApp extends StatefulWidget {
  @override
  State<DemoApp> createState() => _DemoAppState();
}

class _DemoAppState extends State<DemoApp> {
  final MyCommunication comm = MyCommunication();
  bool _showPopup = false;

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

  void _start() {
    setState(() => _showPopup = true);
    comm.startSimulatedTransfer();
  }

  @override
  Widget build(BuildContext context) {
    return MaterialApp(
      home: Scaffold(
        appBar: AppBar(title: const Text('Popup Progress Demo')),
        body: Stack(
          children: [
            Center(
              child: ElevatedButton(
                onPressed: _start,
                child: const Text('Starte Transfer'),
              ),
            ),
            if (_showPopup)
              PopupMessage(
                stream: comm.incomingStream,
                onDone: () {
                  // Popup nach kurzer Verzögerung schließen
                  Future.delayed(const Duration(milliseconds: 400), () {
                    setState(() => _showPopup = false);
                  });
                },
              ),
          ],
        ),
      ),
    );
  }
}

void main() => runApp(DemoApp());