chunhtai 26037dff87
Add set semantics enabled API and wire iOS a11y bridge (#161265)
fixes https://github.com/flutter/flutter/issues/158399

old pr https://github.com/flutter/engine/pull/56691

previously the only correct way to enable semantics is that ios
embedding receive signal from native OS, it call SetSemanticsEnabled to
shell and then to dart to enable semantics tree generation.

If for some reason framework decide to enable semantics first, e.g.
through SemanticsBinding.instance.ensureSemantics(typically due to
integration test or ci that wants to test semantics), the update will be
dropped in shell. Even if it later on receive signal from native OS to
turn on semantics, it can't construct the complete accessibility tree in
embedding because the updatesemantics sends diff update and previous
updates are gone forever. It will end up in a broken state.

This pr changes so that the only source of truth will be in the
framework side. When framework starts generating the the semantics tree,
it will call SetSemanticsTreeEnabled through dart:ui, and the embedding
needs to prepare itself to accept semantics update after receiving the
message.

This however require some refactoring on iOS embedding because it will
only create a11y bridge when receiving OS notification when assitive
technologies turns on.

This requires three phase transition

add an empty dart:ui API setSemanticsTreeEnabled
makes framework calls the empty API.
merge this pr with actual implementation of setSemanticsTreeEnabled

I will do the android part in a separate pr


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2025-03-24 20:11:13 +00:00
..

iOS host app

Used by the module_test_ios.dart device lab test.

iOS host app for a Flutter module created using

$ flutter create -t module hello

and placed in a sibling folder to (a clone of) the host app. flutterapp/lib/marquee.dart and flutterapp/lib/main.dart must be copied into the new module lib for platform unit tests to pass.

This application demonstrates some basic functionality for Add2App, along with a native iOS ViewController as a baseline and to demonstrate interaction.

  1. A regular iOS view controller (UIViewController), similar to the default flutter create template (NativeViewController.m).
  2. A FlutterViewController subclass that takes over the full screen. Demos showing this both from a cold/fresh engine state and a warm engine state (FullScreenViewController.m).
  3. A demo of pushing a FlutterViewController on as a child view.
  4. A demo of showing both the native and the Flutter views using a platform channel to interact with each other (HybridViewController.m).
  5. A demo of showing two FlutterViewControllers simultaneously (DualViewController.m).

A few key things are tested here (FlutterUITests.m):

  1. The ability to pre-warm the engine and attach/detach a ViewController from it.
  2. The ability to use platform channels to communicate between views.
  3. The ability to simultaneously run two instances of the engine.