Currently, all Flutter threads are managed by the engine itself. This works for
all threads except the platform thread. On this thread, the engine cannot see
the underlying event multiplexing mechanism. Using the new task runner
interfaces, the engine can relinquish the task of setting up the event
multiplexing mechanism and instead have the embedder provide one for it during
setup.
This scheme is only wired up for the platform thread. But, the eventual goal
is to expose this message loop interoperability for all threads.
This allows for the specification of std::functions (using EmbedderContext::NativeEntry) with their captures as native entrypoints. Earlier, only C functions we allowed which meant that there were no captures and assertions had to use globals which could introduce bugs when used with gtest_repeat.
All embedder unit-tests have to setup the Flutter project arguments from scratch
before launching the engine. The boilerplate and having to deal with the low
level C API during each engine launch is a hinderance to writing tests.
This patch introduces an EmbedderTest fixture that sets up all the embedder side snapshots before allowing the unit test to create a FlutterConfigBuilder` that
the test can use to incrementally build and edit the Flutter project
configuration. From the given state state of a configuration, multiple engines
can be launched with their lifecylces managed by appropriate RAII wrappers.
This allows the a fully configured Flutter engine to be launched using 4 lines
of code in a fixture.
```
EmbedderConfigBuilder builder;
builder.SetSoftwareRendererConfig();
builder.SetAssetsPathFromFixture(this);
builder.SetSnapshotsFromFixture(this);
auto engine = builder.LaunchEngine();
```
This will allow us to easily visualize the time the platform informed the engine of a vsync event, its arguments, and when the engine began its UI thread workload using this information.
Verified that the tests fail on issues like https://github.com/flutter/engine/pull/8166. Unfortunately, there is no x-platform way to perform this check but this should gate incorrect traces being added to the engine.
Some embedders may have to wait on fences asynchronously before committing
contents. This allows them to post a task onto the engine managed thread used
for rendering.
Some clients (e.g., embedded devices) prefer generating persistent cache files for the specific device beforehand, and ship them as readonly files in OTA packages.
This updates the FlutterSemanticsAction enumerator identifiers for the
'move cursor forward/back one word' actions (added in
flutter/engine#8033) for consistency with the 'move cusor forward/back
on character' identifiers.
ABI compatibility is unaffected, but this with require the following
change in any embedder making use of these fields:
Rename:
kFlutterSemanticsActionMoveCursorForwardByWordIndex
to:
kFlutterSemanticsActionMoveCursorForwardByWord
Rename:
kFlutterSemanticsActionMoveCursorBackwardByWordIndex
to:
kFlutterSemanticsActionMoveCursorBackwardByWord
The current assumption is that the embedder will wait till the vsync event and
then fire the callback. However, some embedders have that information upfront.
Since the time point has already been specified by the embedder, there is no
reason to burden the embedder with having to setup a wait either.
Adds support for pointer signals, in a way that will support both discrete events (e.g., scroll wheels, flutter/flutter#22762) and continuous gestures (e.g., trackpad scroll, flutter/flutter#21953).
Also exposes these new event options to the embedder. Does not include code to send the
new events from the platform shells.
This brings the Dart and C++ semantics flag enums back in sync.
In #5902, the ability to move the cursor forward and backward one word
were added to dart:ui, and to the Android embedder, but not to the
SemanticsAction enum on the C++ side.
This brings the Dart and C++ semantics flag enums back in sync.
In #5941, implicit scrolling support was added to SemanticsFlag in
dart:ui, and to the Android embedder, but not to the SemanticsFlags enum
on the C++ side.
This also clarifies/corrects the documentation for this value in dart:ui
and in the embedder API.
Previously the transformation matrix returned on semantics nodes was
fetched by matrix col,row (incorrectly). This uses the SkMatrix
constants instead and adds a test.
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.
Link dart:* sources into engine for debugger source support
Currently, dart:* libraries appear to have no source in
debuggers like Observatory. With this change, these sources will be
available in debug mode applications. Sources for dart:* libraries are
lazily loaded on a script-by-script basis.
Refer to https://dart-review.googlesource.com/c/sdk/+/93375 for the Dart
SDK change.
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).
Behavior (visual) changes should be very minor. Things that are to be expected:
* A few things were not color managed correctly by the transform canvas (color emoji, some color filters). Those will be handled correctly with the tagged surfaces (although we're always transforming to sRGB, so nothing should change until we target a wider gamut).
* Image filtering will happen in the source color space, rather than the destination. Very minor.
* The transform canvas did caching of images in the destination color space. Now, the conversion happens at draw time. If there are performance issues, images can be pre-converted to the destination with makeColorSpace().
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.
