first commit

lib/services/download_update_stream.dart

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+import 'dart:async';
+import 'dart:isolate';
+import 'dart:ui';
+
+import 'package:flutter_downloader/flutter_downloader.dart';
+
+class DownloadUpdate {
+  DownloadUpdate({
+    required this.id,
+    required this.status,
+    required this.progress,
+  });
+
+  final String id;
+  final DownloadTaskStatus status;
+  final int progress;
+}
+
+/// This stream is used to provide download updates in the UI. A single callback
+/// in main.dart adds all of flutter_downloader's events to this stream so that
+/// changes can be easily listened to in widgets.
+class DownloadUpdateStream {
+  final ReceivePort _port = ReceivePort();
+  // ignore: close_sinks
+  final _controller = StreamController<DownloadUpdate>.broadcast();
+
+  Stream<DownloadUpdate> get stream => _controller.stream;
+
+  void setupSendPort() {
+    IsolateNameServer.registerPortWithName(
+        _port.sendPort, 'downloader_send_port');
+    _port.listen((dynamic data) {
+      String id = data[0];
+      DownloadTaskStatus status = DownloadTaskStatus(data[1]);
+      int progress = data[2];
+
+      add(DownloadUpdate(
+        id: id,
+        status: status,
+        progress: progress,
+      ));
+    });
+  }
+
+  /// Add a new download update to the download update stream.
+  void add(DownloadUpdate downloadUpdate) => _controller.add(downloadUpdate);
+}