androidflutterflame

Flutter/Flame: `The getter 'delta' isn't defined for the type 'DragUpdateEvent'` despite clean install and correct dependencies

I'm facing a persistent error in a minimal Flutter/Flame project that seems to defy all standard debugging steps. The analyzer insists that the delta getter is not defined on DragUpdateEvent, even though my setup appears to be perfectly correct.

The Error: The getter 'delta' isn't defined for the type 'DragUpdateEvent'.

Minimal Reproducible Code (in lib/main.dart):

import 'package:flame/game.dart';
import 'package:flame/events.dart';
import 'package:flutter/material.dart';

void main() {
  runApp(GameWidget(game: MyGame()));
}

class MyGame extends FlameGame with DragCallbacks {
  @override
  void onDragUpdate(DragUpdateEvent event) {
    super.onDragUpdate(event);
    // The error occurs on the line below:
    final delta = event.delta;
    print('Drag delta: $delta');
  }
}

My pubspec.yaml dependencies:

dependencies:
  flutter:
    sdk: flutter
  flame: ^1.17.0

My flutter doctor -v output is clean:

[✓] Flutter (Channel stable, 3.32.2, on Microsoft Windows [Version 10.0.19045.5917], locale pt-BR)
    • Flutter version 3.32.2 on channel stable at C:\Users\Windows\dev\flutter
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 8defaa71a7 (6 days ago), 2025-06-04 11:02:51 -0700
    • Engine revision 1091508939
    • Dart version 3.8.1
    • DevTools version 2.45.1

[✓] Windows Version (10 Pro 64-bit, 22H2, 2009)
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.1)
[✓] Chrome - develop for the web
[!] Visual Studio - develop Windows apps (Not relevant for this issue)
[✓] Android Studio (version 2024.3.2)
[✓] Connected device (3 available)
[✓] Network resources

Exhaustive List of Steps I've Already Taken:

  1. Confirmed the code final delta = event.delta; is correct for Flame ^1.17.0.
  2. Created a brand new project (flutter create) to isolate the issue. The error persists.
  3. Ran flutter clean.
  4. Deleted pubspec.lock and ran flutter pub get.
  5. Ran flutter pub cache repair to fix the global pub cache.
  6. Completely reinstalled the Flutter SDK by downloading a fresh copy of 3.32.2-stable and updating the PATH environment variable. flutter doctor -v confirms the new installation is being used.
  7. Completely uninstalled and reinstalled the Dart and Flutter extensions in VS Code.
  8. Restarted the IDE and the computer multiple times.

Despite all this, the Dart Analysis Server in VS Code continues to report this incorrect error. Does anyone have any idea what could cause such a persistent, environment-level issue that survives even a full SDK reinstallation?

Solution

  • You're using flame: ^1.17.0, but DragUpdateEvent does not have a delta getter in that version.

    The delta getter you're referring to was introduced in Flame 1.18.0 onwards, and is not available in 1.17.0.

    Update your pubspec.yaml to use at least version of Flame. the latest version is here:

    [https://pub.dev/packages/flame/install](Flame Latest Version)

    dependencies:
  flutter:
    sdk: flutter
  flame: ^1.29.0

    Then run:

    flutter pub get

    Now the line final delta = event.delta; should work as expected.