Memory leak detection with leak_tracker_flutter_testing

[kosratdev]

Describe the bug
After adding the leak_tracker_flutter_testing dependency to the dev dependencies to detect memory leaks while running the tests. I found two memory leaks that happens multiple times in different tests. They are not disposed objects as listed below:

• PanGestureRecognizer object in render_base_chart.dart file
• TapGestureRecognizer object in render_base_chart.dart file
• LongPressGestureRecognizer object in render_base_chart.dart file

The above memory leaks can be fixed easily just by disposing them in the detach method like below:

  @override
  void detach() {
    _validForMouseTracker = false;
    panGestureRecognizer.dispose();
    tapGestureRecognizer.dispose();
    longPressGestureRecognizer.dispose();
    super.detach();
  }

Furthermore, it has some other memory leaks, which are hard for me to fix as I'm not very familiar with the source code architecture.

• TransformationController in axis_chart_scaffold_widget.dart file.
• TransformationController in custom_interactive_viewer.dart file.

To Reproduce

• Add leak_tracker_flutter_testing to the dev dependancies

dev_dependencies:
  ...
  leak_tracker_flutter_testing: any

• Create flutter_test_config.dart file in the root of the test folder

import 'dart:async';

import 'package:leak_tracker_flutter_testing/leak_tracker_flutter_testing.dart';

Future<void> testExecutable(FutureOr<void> Function() testMain) async {
  LeakTesting.enable();
  LeakTesting.settings = LeakTesting.settings
    .withIgnored(createdByTestHelpers: true);

  await testMain();
}

• run tests to see detected memory leaks.

Screenshots
If applicable, add screenshots, or videoshots to help explain your problem.

Versions

• Flutter Version: 3.35.1
• FlChart Version: 1.0.0

I want to create a pull request to fix those memory leaks, but I can't fix the TransformationController leaks unless you help me.

[imaNNeo]

Hi @kosratdev
Good catch and thanks for your detailed issue

At the moment, I don't have time to test them.
Can you please check if those .dispose() calls fix the issue and if they don't break anything, open a PR?

For the other one (transformer controller), we need more investigation.
Maybe @Peetee06 can help us on that

[peter-trost]

Hey there, thanks for flagging these memory leaks!

I don't have any capacity to look into this myself right now, but am happy to answer questions if there are specific ones..

[harikrishna-au]

As suggested by @imaNNeo and @Peetee06, I will dispose the gesture recognizers in render_base_chart.dart within the detach() method, and ensure proper disposal of TransformationController in the relevant State.dispose() methods. I will verify the fixes using leak_tracker_flutter_testing and then open a PR referencing this issue.