present() now snapshots the PaintingSurface into an ImmutableBitmap
and publishes it to the ExternalContentSource, so the rendering thread
never touches the live GPU surface — eliminating the data race
described in the ExternalContentSource commit (problem 1).
Canvas elements are registered with Page and presented once per frame
from the event loop, rather than on every individual draw call in
CRC2D::did_draw(). A dirty flag on HTMLCanvasElement ensures the
snapshot is only taken when content has actually changed, and makes
the present() call in CanvasPaintable::paint() a no-op when the
surface has already been snapshotted for the current frame.
By making use of the WEB_PLATFORM_OBJECT macro we can remove
the boilerplate of needing to add this override for every
serializable platform object so that we can check whether they
are exposed or not.
This saves us from having our own color conversion code, which was
taking up a fair amount of time in VideoDataProvider. With this change,
we should be able to play high resolution videos without interruptions
on machines where the CPU can keep up with decoding.
In order to make this change, ImmutableBitmap is now able to be
constructed with YUV data instead of an RBG bitmap. It holds onto a
YUVData instance that stores the buffers of image data, since Skia
itself doesn't take ownership of them.
In order to support greater than 8 bits of color depth, we normalize
the 10- or 12-bit color values into a 16-bit range.
This factors the conversion logic to be independent from WebGL code,
allowing us to write unit tests for it that can run in CI (since WebGL
can't run in CI).
This makes the WebGL2 implementation file inherit from the WebGL1
implementation file. This is actually closer to what the IDL files
describe and allows us to not have to maintain two copies of the same
functions.
The reasoning behind this is that in the next commit some of the WebGL2
specific parameters will be moved here. This header is needed to give
us access to those defines. Note that when in WebGL1 nothing from ES3
will be used as it's locked behind WebGL2 checks (it wouldn't work
anyways as we request ES2 from ANGLE).
This is more like what the IDL files specify with two different mixins,
but the inheritance structure here is slightly different for easier
maintenance. This will also allow the WebGL2 Impl to inherit from the
WebGL1 Impl as WebGL versions don't share the functions defined in the
Overloads interfaces.
The spec actually mandates that clientWaitSync actually has a time
limit and this is a way to get it. For now just return infinity as this
is required of SpectorJS to work.
