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.
From build log:
```
../../flutter/shell/platform/android/io/flutter/view/FlutterView.java:95: error: cannot find symbol
private final LocalizationChannel localizationChannel;
^
symbol: class LocalizationChannel
location: class FlutterView
../../flutter/shell/platform/android/io/flutter/view/FlutterView.java:172: error: cannot find symbol
localizationChannel = new LocalizationChannel(dartExecutor);
^
symbol: class LocalizationChannel
location: class FlutterView
2 errors
```
This reverts commit 256db4bc23.
The shell was already designed to cleanly shut down the VM but it couldnt
earlier as |Dart_Initialize| could never be called after a |Dart_Cleanup|. This
meant that shutting down an engine instance could not shut down the VM to save
memory because newly created engines in the process after that point couldn't
restart the VM. There can only be one VM running in a process at a time.
This patch separate the previous DartVM object into one that references a
running instance of the DartVM and a set of immutable dependencies that
components can reference even as the VM is shutting down.
Unit tests have been added to assert that non-overlapping engine launches use
difference VM instances.
Added `FlutterPluginRegistrantCallback` typedef and optional `setPluginRegistrantCallback` static method in `FlutterPlugin`. `setPluginRegistrantCallback` is used to set a callback defined in AppDelegate.m which registers some subset of plugins with a `FlutterPluginRegistry` (for example, a headless FlutterEngine). This allows for plugins which utilize background execution functionality to enable the use of other plugins on the background isolate. This puts iOS on par with Android for background execution.
Along with updated examples and Medium posts, this fixes [flutter/flutter#21925](https://github.com/flutter/flutter/issues/21925).
Stanislav Baranov
Chris Bracken
Chinmay Garde
Matt Carroll
Dan Field
stuartmorgan
Todd Volkert
Amir Hardon
najeira
Ben Konyi
Jason Simmons
Gary Qian
nathanrogersgoogle