first commit

lib/services/file_picker_service_web.dart

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+import 'dart:async';
+import 'dart:html';
+import 'dart:typed_data';
+
+Future<Uint8List?> pickImageBytes() async {
+  final completer = Completer<Uint8List?>();
+
+  final input = FileUploadInputElement()
+    ..accept = 'image/*'
+    ..click();
+
+  // Detect cancellation: when user closes the file dialog without picking,
+  // onChange won't fire, but window.onFocus will when focus returns.
+  StreamSubscription<Event>? focusSub;
+  focusSub = window.onFocus.listen((_) {
+    focusSub?.cancel();
+    if (!completer.isCompleted) {
+      completer.complete(null);
+    }
+  });
+
+  input.onChange.listen((_) {
+    focusSub?.cancel();
+
+    final file = input.files?.first;
+    if (file == null) {
+      completer.complete(null);
+      return;
+    }
+
+    final reader = FileReader();
+    reader.onLoad.listen((_) {
+      completer.complete(reader.result as Uint8List);
+    });
+
+    reader.onError.listen((_) {
+      completer.complete(null);
+    });
+
+    reader.readAsArrayBuffer(file);
+  });
+
+  return completer.future;
+}