Currently we run some tasks on the UI thread that shouldn't block the frame,
such as decoding images. This patch introduces a background thread on which we
can run these tasks.
Dart code now supports the full flow that the C++ code used to: version check,
download, replace app bundle. Bonus: the Dart code is much easier to follow,
thanks to async/await!
This is part 2 of a 3-part change. The first part added new mojom
interfaces, PathService and UpdateService, to the sky_services package.
This adds a new placeholder dart package updater in sky/packages. This is built
into a snapshot and compiled into the Sky engine binary using the same
mechanism as the Dart isolate.
I also added a SkyHeadless class, similar to SkyView, used for running Dart
code without a view.
We still use SkPicture as our rasterization backend, but now we're uploading
our layer tree to C++. A future patch will push the layer tree deeper into the
system and we'll eventually switch backends.
The primary goal of this change was to remove EventTarget from the
sky_engine C++ code. Since EventTarget is so core to the entire event
system that sky_engine was based on, this is a rather invasive change.
As such, it had some knock-on effects. I deleted some of the files
that were affected, and cauterised the remainder.
In many cases, a file would depend on another file that it didn't
include directly, but instead included indirectly via another file
that I deleted. When this happened, if the features that this broke
were obsolete, I sometimes just removed the features instead.
Specifically:
- removed EventTarget
- removed EventQueue, since without a target, what's a queue going to
do?
- same with EventDispatch*
- removed ExecutionContext, since it had an EventQueue and nothing
else it did was relevant to Sky anymore
- removed ActiveDOMObject, which was all about ExecutionContexts
- removed ContextLifecycleNotifier since it dependend on
ExecutionContext and ActiveDOMObject
- removed the other Lifecycle classes for consistency, and replaced
them with four booleans in the Document class
- removed some of the attributes that are no longer relevant from
IDLExtendedAttributes (ConstructorCallWith and
CallWith=ExecutionContext)
- removed the Document member on DOMDartState since we never set it to
anything but null.
- removed BuiltinSky::InstallWindow since it relied on the Document
member of DOMDartState
- removed EventHandler, EventListener, and mentions of those in
various binding scripts
- removed NewEventHandler, since we're not using that either
- removed the following interfaces from the Sky Dart API:
- EventTarget
- EventListener (since without a target, there's no way to listen)
- FocusEvent (since it's only member was an EventTarget)
- HashChangeEvent (mostly by accident, but it's defunct anyway)
- FontFace (it used ConstructorCallWith=ExecutionContext)
- changed the following interfaces of the Sky DART API:
- MediaQueryList is no longer an EventTarget
- Node is no longer an EventTarget
- Document no longer has defaultView (depended on
DOMDartState's document)
- DocumentFragment, Element, Range, and Text no longer have a
constructor (they all depended on DOMDartState's document, which
is now gone)
- Event lost its EventTarget members and path.
- Window lost its WindowTimers partial interface (it used
EventTarget and ExecutionContext a lot)
- removed numerous hacks in the bindings around features that are now
gone, like addEventListener
- removed a bunch of console logging code, since that relied on
ExecutionContext
- cauterised the wound in FontFace.cpp by removing constructors and
methods that called now-removed features
- same with MediaQuery and friends
- same with some editor features and focus-related features
- same with Document
- removed DOMTimer classes since they use ExecutionContexts
