[two_dimensional_scrollables] TreeView Widget blanks when closing last parent #149182

yahooooza · 2024-05-28T14:56:50Z

Steps to reproduce

Open a TreeView such that all Elements exceeds screensize height
Scroll down to the latest Item. This Item should be a parent of other items
Open the item and then close it.

Failure is also reproducable with the given example from the library.

Tested on Linux and Windows

Expected results

The item should close normally.

Actual results

The whole tree disappears and i get the following exception. After scrolling up and down the tree reappears.

The following _TypeError was thrown during paint():
Null check operator used on a null value

The relevant error-causing widget was: 
  TreeView<WorkPackage> TreeView:file:///<projectpathfile>
When the exception was thrown, this was the stack: 
#0      RenderTreeViewport._paintRows (package:two_dimensional_scrollables/src/tree_view/render_tree.dart:594:8)
#1      RenderTreeViewport.paint.<anonymous closure> (package:two_dimensional_scrollables/src/tree_view/render_tree.dart:422:13)
#2      PaintingContext.pushLayer (package:flutter/src/rendering/object.dart:486:12)
#3      PaintingContext.pushClipRect (package:flutter/src/rendering/object.dart:546:7)
#4      RenderTreeViewport.paint (package:two_dimensional_scrollables/src/tree_view/render_tree.dart:417:57)
#5      RenderObject._paintWithContext (package:flutter/src/rendering/object.dart:3239:7)
#6      PaintingContext._repaintCompositedChild (package:flutter/src/rendering/object.dart:166:11)
#7      PaintingContext.repaintCompositedChild (package:flutter/src/rendering/object.dart:109:5)

Code sample

// Copyright 2013 The Flutter Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import 'package:flutter/material.dart';

import 'custom_tree.dart';
import 'simple_tree.dart';

/// The page containing the interactive controls that modify the sample
/// TreeView.
class TreeExplorer extends StatefulWidget {
  /// Creates a screen that demonstrates the TreeView widget in varying
  /// configurations.
  const TreeExplorer({super.key});

  @override
  State<TreeExplorer> createState() => _TreeExplorerState();
}

/// Which example is being displayed.
enum TreeType {
  /// Displays TreeExample.
  simple,

  /// Displays CustomTreeExample.
  custom,
}

class _TreeExplorerState extends State<TreeExplorer> {
  final SizedBox _spacer = const SizedBox.square(dimension: 20.0);
  TreeType _currentExample = TreeType.simple;
  String _getTitle() {
    return switch (_currentExample) {
      TreeType.simple => 'Simple TreeView',
      TreeType.custom => 'Customizing TreeView',
    };
  }

  Widget _getTree() {
    return switch (_currentExample) {
      TreeType.simple => const TreeExample(),
      TreeType.custom => const CustomTreeExample(),
    };
  }

  Widget _getRadioRow() {
    return Padding(
      padding: const EdgeInsets.all(8.0),
      child: Row(
        children: <Widget>[
          const Spacer(),
          Radio<TreeType>(
            value: TreeType.simple,
            groupValue: _currentExample,
            onChanged: (TreeType? value) {
              setState(() {
                _currentExample = value!;
              });
            },
          ),
          const Text('Simple'),
          _spacer,
          Radio<TreeType>(
            value: TreeType.custom,
            groupValue: _currentExample,
            onChanged: (TreeType? value) {
              setState(() {
                _currentExample = value!;
              });
            },
          ),
          const Text('Custom'),
          const Spacer(),
        ],
      ),
    );
  }

  @override
  Widget build(BuildContext context) {
    return Scaffold(
      appBar: AppBar(
        title: Text(_getTitle()),
        bottom: PreferredSize(
          preferredSize: const Size.fromHeight(50),
          child: Padding(
            padding: const EdgeInsets.all(8.0),
            child: _getRadioRow(),
          ),
        ),
      ),
      body: _getTree(),
    );
  }
}

Screenshots or Video

Screenshots / Video demonstration

2024-05-28.17-00-23.mp4

treeview.2024-05-28.17-11-15.mp4

Logs

No response

Flutter Doctor output

Doctor output

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.22.1, on Manjaro Linux 6.8.9-3-MANJARO, locale de_DE.UTF-8)
[✓] Android toolchain - develop for Android devices (Android SDK version 33.0.0)
[✓] Chrome - develop for the web
[✓] Linux toolchain - develop for Linux desktop
[✓] Android Studio (version 2023.3)
[✓] Connected device (2 available)
[✓] Network resources

• No issues found!

darshankawar · 2024-05-29T07:52:35Z

@yahooooza Can you provide us a runnable reproducible code sample that triggers the reported log ?

yahooooza · 2024-05-29T08:33:47Z

@darshankawar As already mentioned, the beaviour appears also in the given example from the library. I update the issue with the example code form the repo. You can see the beaviour in the second video i posted under "Screenshots or Video".

darshankawar · 2024-05-29T12:19:08Z

Thanks for the update. Using the code sample provided and running on desktop, I was able to replicate the reported error.

stable, master flutter doctor -v

[!] Flutter (Channel stable, 3.22.0, on macOS 12.2.1 21D62 darwin-x64, locale
    en-GB)
    • Flutter version 3.22.0 on channel stable at
      /Users/dhs/documents/fluttersdk/flutter
    ! Warning: `flutter` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/flutter, which is not inside
      your current Flutter SDK checkout at
      /Users/dhs/documents/fluttersdk/flutter. Consider adding
      /Users/dhs/documents/fluttersdk/flutter/bin to the front of your path.
    ! Warning: `dart` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/dart, which is not inside your
      current Flutter SDK checkout at /Users/dhs/documents/fluttersdk/flutter.
      Consider adding /Users/dhs/documents/fluttersdk/flutter/bin to the front
      of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 5dcb86f68f (5 days ago), 2024-05-09 07:39:20 -0500
    • Engine revision f6344b75dc
    • Dart version 3.4.0
    • DevTools version 2.34.3
    • If those were intentional, you can disregard the above warnings; however
      it is recommended to use "git" directly to perform update checks and
      upgrades.

[!] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    ! Flutter recommends a minimum Xcode version of 13.
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (5 available)
    • SM G975F (mobile)       • RZ8M802WY0X • android-arm64   • Android 11 (API 30)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 98.0.4758.80

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

[!] Flutter (Channel master, 3.23.0-12.0.pre.7, on macOS 12.2.1 21D62
    darwin-x64, locale en-GB)
    • Flutter version 3.23.0-12.0.pre.7 on channel master at
      /Users/dhs/documents/fluttersdk/flutter
    ! Warning: `flutter` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/flutter, which is not inside
      your current Flutter SDK checkout at
      /Users/dhs/documents/fluttersdk/flutter. Consider adding
      /Users/dhs/documents/fluttersdk/flutter/bin to the front of your path.
    ! Warning: `dart` on your path resolves to
      /Users/dhs/Documents/Fluttersdk/flutter/bin/dart, which is not inside your
      current Flutter SDK checkout at /Users/dhs/documents/fluttersdk/flutter.
      Consider adding /Users/dhs/documents/fluttersdk/flutter/bin to the front
      of your path.
    • Upstream repository https://github.com/flutter/flutter.git
    • Framework revision 35ae519140 (2 hours ago), 2024-05-29 00:33:07 -0400
    • Engine revision b26e1b023c
    • Dart version 3.5.0 (build 3.5.0-191.0.dev)
    • DevTools version 2.36.0-dev.10
    • If those were intentional, you can disregard the above warnings; however
      it is recommended to use "git" directly to perform update checks and
      upgrades.

[!] Android toolchain - develop for Android devices (Android SDK version 30.0.3)
    • Android SDK at /Users/dhs/Library/Android/sdk
    ✗ cmdline-tools component is missing
      Run `path/to/sdkmanager --install "cmdline-tools;latest"`
      See https://developer.android.com/studio/command-line for more details.
    ✗ Android license status unknown.
      Run `flutter doctor --android-licenses` to accept the SDK licenses.
      See https://flutter.dev/docs/get-started/install/macos#android-setup for
      more details.

[✓] Xcode - develop for iOS and macOS (Xcode 13.2.1)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    • Build 13C100
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] IntelliJ IDEA Ultimate Edition (version 2021.3.2)
    • IntelliJ at /Applications/IntelliJ IDEA.app
    • Flutter plugin version 65.1.4
    • Dart plugin version 213.7228

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.29.0

[✓] Connected device (3 available)
    • Darshan's iphone (mobile) • 21150b119064aecc249dfcfe05e259197461ce23 • ios
      • iOS 15.3.1 19D52
    • macOS (desktop)           • macos                                    •
      darwin-x64     • macOS 12.2.1 21D62 darwin-x64
    • Chrome (web)              • chrome                                   •
      web-javascript • Google Chrome 109.0.5414.119

[✓] Network resources
    • All expected network resources are available.

! Doctor found issues in 1 category.
      
[!] Xcode - develop for iOS and macOS (Xcode 12.3)
    • Xcode at /Applications/Xcode.app/Contents/Developer
    ! Flutter recommends a minimum Xcode version of 13.
      Download the latest version or update via the Mac App Store.
    • CocoaPods version 1.11.2

[✓] Chrome - develop for the web
    • Chrome at /Applications/Google Chrome.app/Contents/MacOS/Google Chrome

[✓] VS Code (version 1.62.0)
    • VS Code at /Applications/Visual Studio Code.app/Contents
    • Flutter extension version 3.21.0

[✓] Connected device (5 available)
    • SM G975F (mobile)       • RZ8M802WY0X • android-arm64   • Android 11 (API 30)
    • Darshan's iphone (mobile)  • 21150b119064aecc249dfcfe05e259197461ce23 •
      ios            • iOS 14.4.1 18D61
    • iPhone 12 Pro Max (mobile) • A5473606-0213-4FD8-BA16-553433949729     •
      ios            • com.apple.CoreSimulator.SimRuntime.iOS-14-3 (simulator)
    • macOS (desktop)            • macos                                    •
      darwin-x64     • Mac OS X 10.15.4 19E2269 darwin-x64
    • Chrome (web)               • chrome                                   •
      web-javascript • Google Chrome 98.0.4758.80

[✓] HTTP Host Availability
    • All required HTTP hosts are available

! Doctor found issues in 1 category.

MichelleWeck · 2025-03-06T08:45:33Z

This problem is still reproducable in the newest Flutter version, 3.29.0. Will there be a fix to this issue?

Collapsing a node when there were other nodes offscreen was causing an unexpected null dereference during painting. This PR fixes the bug and adds a test. The bug was caused by erroneous computation of the max vertical scroll extent. Previously, the code computed this considering only scroll extent in the trailing (down) direction; it may also be the case that there is a larger scroll extent in the leading (up) direction. The miscalculation resulted in subsequent error computing the first visible row as a row that is actually offscreen, and thus does not have a render box. The row render box is asserted to be non-null during painting. Fixes flutter/flutter#149182 Fixes flutter/flutter#164981

Collapsing a node when there were other nodes offscreen was causing an unexpected null dereference during painting. This PR fixes the bug and adds a test. The bug was caused by erroneous computation of the max vertical scroll extent. Previously, the code computed this considering only scroll extent in the trailing (down) direction; it may also be the case that there is a larger scroll extent in the leading (up) direction. The miscalculation resulted in subsequent error computing the first visible row as a row that is actually offscreen, and thus does not have a render box. The row render box is asserted to be non-null during painting. Fixes flutter/flutter#149182 and flutter/flutter#164981

darshankawar added the in triage Presently being triaged by the triage team label May 29, 2024

darshankawar added the waiting for customer response The Flutter team cannot make further progress on this issue until the original reporter responds label May 29, 2024

github-actions bot removed the waiting for customer response The Flutter team cannot make further progress on this issue until the original reporter responds label May 29, 2024

goderbauer added P2 Important issues not at the top of the work list triaged-framework Triaged by Framework team labels Jun 4, 2024

tdenniston mentioned this issue Apr 16, 2025

[two_dimensional_scrollables] Unexpected null value on collapse of the last TreeView node #164981

Open

tdenniston linked a pull request Apr 17, 2025 that will close this issue

[two_dimensional_scrollables] Fix TreeView null dereference during paint flutter/packages#9103

Open

11 tasks

Piinks added the waiting for PR to land (fixed) A fix is in flight label Apr 17, 2025

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[two_dimensional_scrollables] TreeView Widget blanks when closing last parent #149182

[two_dimensional_scrollables] TreeView Widget blanks when closing last parent #149182

yahooooza commented May 28, 2024 •

edited

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darshankawar commented May 29, 2024

yahooooza commented May 29, 2024

darshankawar commented May 29, 2024

MichelleWeck commented Mar 6, 2025

[two_dimensional_scrollables] TreeView Widget blanks when closing last parent #149182

[two_dimensional_scrollables] TreeView Widget blanks when closing last parent #149182

Comments

yahooooza commented May 28, 2024 • edited Loading

Steps to reproduce

Expected results

Actual results

Code sample

Screenshots or Video

Logs

Flutter Doctor output

darshankawar commented May 29, 2024

yahooooza commented May 29, 2024

darshankawar commented May 29, 2024

MichelleWeck commented Mar 6, 2025

yahooooza commented May 28, 2024 •

edited

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