Some embedders prefer to minimise the number of semantics node/custom
action updates sent back to the host platform -- for example due to
expensive serialisation mechanisms, etc.
This patch provides a 'batch end' signal that provides embedders with an
indication of when a self-consistent set of semantics node or custom action
updates have been sent.
We overload the node/action ID with information that conveys a batch end
by using an ID (-1) that is never allotted to semantics nodes by the
framework.
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.
Adds 'add', 'remove', and 'hover' to the set of pointer phases that are
available to embedders. This is necessary for them to send hover events
to the engine.
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.
* The Flutter engine will be shipped as a shared library.
* The engine is renderer and window toolkit agnostic.
* The simple public C API is described in embedder.h.
* ABI breaking changes will be indicated by changing the FLUTTER_ENGINE_VERSION.
* A simple GLFW based example of this API is available at https://gist.github.com/chinmaygarde/8abf44921f7d87f6da7bf026267c4792
