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flutter/examples/layers
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Loïc Sharma ce61eda70c
[Windows] Ensure window is shown (#127046) 
## Background

The Windows runner has a race at startup:

1. **Platform thread**: creates a hidden window
2. **Platform thread**: launches the Flutter engine
3. **UI/Raster threads**: renders the first frame
4. **Platform thread**: Registers a callback to show the window once the next frame has been rendered.

Steps 3 and 4 happen in parallel and it is possible for step 3 to complete before step 4 starts. In this scenario, the next frame callback is never called and the window is never shown.

As a result the `windows_startup_test`'s test, which [verifies that the "show window" callback is called](1f09a8662d/dev/integration_tests/windows_startup_test/windows/runner/flutter_window.cpp (L60-L64)), can flake if the first frame is rendered before the show window callback has been registered.

## Solution

This change makes the runner schedule a frame after it registers the next frame callback. If step 3 hasn't completed yet, this no-ops as a frame is already scheduled. If step 3 has already completed, a new frame will be rendered, which will call the next frame callback and show the window.

Part of https://github.com/flutter/flutter/issues/119415

See this thread for alternatives that were considered: https://github.com/flutter/engine/pull/42061#issuecomment-1550080722
2023-05-19 22:25:55 +00:00
..
android Fix warning in flutter created project ("package attribute is deprecated" in AndroidManifest) (#123426) 2023-03-29 04:21:03 +00:00
ios Migrate Xcode projects last version checks to Xcode 14.3 (#125827) 2023-05-02 00:06:33 +00:00
lib License update (#45373) 2019-11-27 15:04:02 -08:00
linux Add Windows and Linux support to the 'layers' example (#126105) 2023-05-06 00:45:19 +00:00
macos Migrate Xcode projects last version checks to Xcode 14.3 (#125827) 2023-05-02 00:06:33 +00:00
raw Remove more references to dart:ui.window (#120994) 2023-02-18 01:50:08 +00:00
rendering Remove unnecessary null checks in examples/ (#118848) 2023-01-20 04:06:04 +00:00
services Remove unnecessary null checks in examples/ (#118848) 2023-01-20 04:06:04 +00:00
test Remove uses of deprecated test_api imports (#124732) 2023-04-20 20:55:28 +00:00
widgets Unify analysis options (#108462) 2022-07-28 09:07:49 -07:00
windows [Windows] Ensure window is shown (#127046) 2023-05-19 22:25:55 +00:00
.metadata Add Windows and Linux support to the 'layers' example (#126105) 2023-05-06 00:45:19 +00:00
analysis_options.yaml Add Windows and Linux support to the 'layers' example (#126105) 2023-05-06 00:45:19 +00:00
pubspec.yaml Upgrade leak_tracker to 5.0.0 (#126367) 2023-05-16 04:39:26 +00:00
README.md ✒ Spell Check All .md Files Related to Flutter 💙 (#61564) 2020-07-22 18:23:47 -07:00

README.md

Examples of Flutter's layered architecture

This directory contains several self-contained examples that illustrate Flutter's layered architecture.

  • raw/ These examples show how to program against the lowest layer of the system. They manually receive input packets and construct composited scenes.

  • rendering/ These examples use Flutter's render tree to structure your app using a retained tree of visual objects. These objects coordinate to determine their size and position on screen and to handle events.

  • widgets/ These examples use Flutter's widgets to build more elaborate apps using a reactive framework.

  • services/ These examples use services available in Flutter to interact with the host platform.

To run each example, specify the demo file on the flutter run command line, for example:

flutter run raw/spinning_square.dart
flutter run rendering/spinning_square.dart
flutter run widgets/spinning_square.dart