Tong Mu e5e8c48753
Fix: Ensure Image.errorBuilder reliably prevents error reporting (with addEphemeralErrorListener) (#167783)
_An alternative to https://github.com/flutter/flutter/pull/166130 using
`addEphemeralErrorListener`.
The following text is adapted from
https://github.com/flutter/flutter/pull/166130._

**Problem:**

Currently, when using an `Image` widget with an `errorBuilder`, if the
widget is removed from the widget tree (e.g., due to navigation or
`setState`) *after* the image loading process has started but *before*
an asynchronous loading error is reported back, the error can still be
reported via `FlutterError.reportError`. This occurs because the
`_ImageState` listener is removed upon disposal, and the
`ImageStreamCompleter` subsequently treats the error as unhandled,
logging it despite the developer's intent to handle it via the
`errorBuilder`. This leads to unexpected noise in logs and crash
reporting systems.

**Solution:**

This PR utilizes `addEphemeralErrorListener`, which allows the image
stream to be disposed while having an error reporter. The error will not
be reported as long as there is an error reporter. The `Image` widget
adds an empty error reporter if `errorBuilder` is not null.

**Related Issues:**

* Fixes #97077
* Related: #107416, #69125, #34451,
Baseflow/flutter_cached_network_image#780

**Tests:**

* Added a new test case `errorBuilder prevents FlutterError report even
if widget is disposed` to `test/widgets/image_test.dart` to specifically
verify the fix for the disposal race condition.
* This test was written by @/perlycke in
https://github.com/flutter/flutter/pull/166130.
* Existing tests in `test/widgets/image_test.dart` (including golden
tests like 'Failed image loads in debug mode') pass with these changes
without requiring updates.

**Breaking Changes:**

* None. This change fixes incorrect behavior and preserves expected
debug visuals. The internal mechanism for reporting errors when no
`errorBuilder` is present has shifted, but the user-facing outcome is
consistent.


## Pre-launch Checklist

- [ ] I read the [Contributor Guide] and followed the process outlined
there for submitting PRs.
- [ ] I read the [Tree Hygiene] wiki page, which explains my
responsibilities.
- [ ] I read and followed the [Flutter Style Guide], including [Features
we expect every widget to implement].
- [ ] I signed the [CLA].
- [ ] I listed at least one issue that this PR fixes in the description
above.
- [ ] I updated/added relevant documentation (doc comments with `///`).
- [ ] I added new tests to check the change I am making, or this PR is
[test-exempt].
- [ ] I followed the [breaking change policy] and added [Data Driven
Fixes] where supported.
- [ ] All existing and new tests are passing.

If you need help, consider asking for advice on the #hackers-new channel
on [Discord].

<!-- Links -->
[Contributor Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#overview
[Tree Hygiene]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md
[test-exempt]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#tests
[Flutter Style Guide]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md
[Features we expect every widget to implement]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Style-guide-for-Flutter-repo.md#features-we-expect-every-widget-to-implement
[CLA]: https://cla.developers.google.com/
[flutter/tests]: https://github.com/flutter/tests
[breaking change policy]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Tree-hygiene.md#handling-breaking-changes
[Discord]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Chat.md
[Data Driven Fixes]:
https://github.com/flutter/flutter/blob/main/docs/contributing/Data-driven-Fixes.md
2025-05-01 17:33:58 +00:00
2025-04-17 15:19:08 +00:00
2025-04-02 19:47:58 +00:00

Flutter

Flutter CI Status Discord badge Twitter handle BlueSky badge codecov CII Best Practices SLSA 1

Flutter is Google's SDK for crafting beautiful, fast user experiences for mobile, web, and desktop from a single codebase. Flutter works with existing code, is used by developers and organizations around the world, and is free and open source.

Documentation

For announcements about new releases, follow the flutter-announce@googlegroups.com mailing list. Our documentation also tracks breaking changes across releases.

Terms of service

The Flutter tool may occasionally download resources from Google servers. By downloading or using the Flutter SDK, you agree to the Google Terms of Service: https://policies.google.com/terms

For example, when installed from GitHub (as opposed to from a prepackaged archive), the Flutter tool will download the Dart SDK from Google servers immediately when first run, as it is used to execute the flutter tool itself. This will also occur when Flutter is upgraded (e.g. by running the flutter upgrade command).

About Flutter

We think Flutter will help you create beautiful, fast apps, with a productive, extensible and open development model, whether you're targeting iOS or Android, web, Windows, macOS, Linux or embedding it as the UI toolkit for a platform of your choice.

Beautiful user experiences

We want to enable designers to deliver their full creative vision without being forced to water it down due to limitations of the underlying framework. Flutter's layered architecture gives you control over every pixel on the screen and its powerful compositing capabilities let you overlay and animate graphics, video, text, and controls without limitation. Flutter includes a full set of widgets that deliver pixel-perfect experiences whether you're building for iOS (Cupertino) or other platforms (Material), along with support for customizing or creating entirely new visual components.

Reflectly hero image

Fast results

Flutter is fast. It's powered by hardware-accelerated 2D graphics libraries like Skia (which underpins Chrome and Android) and Impeller. We architected Flutter to support glitch-free, jank-free graphics at the native speed of your device.

Flutter code is powered by the world-class Dart platform, which enables compilation to 32-bit and 64-bit ARM machine code for iOS and Android, JavaScript and WebAssembly for the web, as well as Intel x64 and ARM for desktop devices.

Dart diagram

Productive development

Flutter offers stateful hot reload, allowing you to make changes to your code and see the results instantly without restarting your app or losing its state.

Hot reload animation

Extensible and open model

Flutter works with any development tool (or none at all), and also includes editor plug-ins for both Visual Studio Code and IntelliJ / Android Studio. Flutter provides tens of thousands of packages to speed your development, regardless of your target platform. And accessing other native code is easy, with support for both FFI (on Android, on iOS, on macOS, and on Windows) as well as platform-specific APIs.

Flutter is a fully open-source project, and we welcome contributions. Information on how to get started can be found in our contributor guide.

Languages
Dart 75%
C++ 16.5%
Objective-C++ 2.9%
Java 2.8%
Objective-C 0.7%
Other 1.9%