Flutter's accessibility APIs consist of three main calls from the
embedder to the Dart application:
1. FlutterEngineUpdateSemanticsEnabled: enables/disables semantics support.
2. FlutterEngineUpdateAccessibilityFeatures: sets embedder-specific
accessibility features.
3. FlutterEngineDispatchSemanticsAction: dispatches an action (tap,
long-press, scroll, etc.) to a semantics node.
and two main callbacks triggered by Dart code:
1. FlutterUpdateSemanticsNodeCallback: notifies the embedder of
updates to the properties of a given semantics node.
2. FlutterUpdateSemanticsCustomActionCallback: notifies the embedder
of updates to custom semantics actions registered in Dart code.
In the Flutter framework, when accessibility is first enabled, the
embedder will receive a stream of update callbacks notifying the
embedder of the full semantics tree. On further changes in the Dart
application, only updates will be sent.
Allows embedders to specify a callback to be invoked in isolate scope
once root isolate has been created and marked runnable.
As an example of where this is useful, embedder unit test fixtures may
want to include Dart functions backed by a native implementation. On
isolate creation, this patch allows the unit test author to call
Dart_SetNativeResolver in root isolate scope.
FlutterResult is also the name of a class in the Objective-C API
surface, which is problematic when building a framework that contains
both (such as a macOS implementation of the Flutter framework).
As of Dart 2, running from Dart source is no longer supported. Dart
code should now be compiled to kernel form and will be loaded by from
kernel.blob in the assets directory. We retain the struct members for ABI
stability. package_path is also not required since kernel blobs are
self-contained.
As of the migration to Dart 2, it has been necessary to compile Dart to
kernel prior to execution. The embedder currently requires that the
resulting kernel file be named `kernel_blob.bin` and be located at the
root of the assets directory passed to the embedder API.
This patch updates the test_fixtures build rule to perform a kernel
compile using frontend_server, outputting `kernel_blob.bin` to
`fixtures/test_target_name` directory, and updates the embedder
unittests to specify the kernel file rather than the Dart source file.
Since the kernel compiler requires a `main()` function to be defined, it
also updates `simple_main.dart` from runtime_unittests to define
`main()` rather than `simple_main()`.
This also updates all existing sub-targets to be testonly.
This relands commit ac9e521a1ddbb99816a93d92ce9fb70e950b3763, which was
reverted in commit 494112582932af98b282617d7a34b1fbb8c90307. Rather than
running as prebuilt_dart_action, we use dart_action to ensure the
frontend snapshot it compatible with the VM on which it's executed.
This reverts commit ac9e521a1ddbb99816a93d92ce9fb70e950b3763.
This broke dynamic release mode builds of
//flutter/runtime:runtime_fixtures_kernel (likely all product-mode
builds).
Compile embedder unit test Dart to kernel
As of the migration to Dart 2, it has been necessary to compile Dart to
kernel prior to execution. The embedder currently requires that the
resulting kernel file be named `kernel_blob.bin` and be located at the
root of the assets directory passed to the embedder API.
This patch updates the test_fixtures build rule to perform a kernel
compile using frontend_server, outputting `kernel_blob.bin` to
`fixtures/test_target_name` directory, and updates the embedder
unittests to specify the kernel file rather than the Dart source file.
Since the kernel compiler requires a `main()` function to be defined, it
also updates `simple_main.dart` from runtime_unittests to define
`main()` rather than `simple_main()`.
This also updates all existing sub-targets to be testonly.
Reduces spurious error log messages in GLContextMakeCurrent() attempting
set up the GR context:
[ERROR:flutter/shell/gpu/gpu_surface_gl.cc(42)] Could not make the context current to setup the gr context.
