Canvas rendering is a major remaining path where WebContent directly
owns GPU-facing drawing state. Back 2D and WebGL canvas contexts with
remote Compositor transports, so WebContent talks to canvas surfaces
through IPC while the Compositor owns the rasterization resources.
This is a large step toward GPU sandboxing because canvas GPU work now
lives behind the Compositor boundary. It also gives OffscreenCanvas the
process-independent canvas plumbing that HTMLCanvasElement now uses,
making worker-owned canvases possible without another WebContent-local
rendering path.
Move CanvasRenderingContext2D onto the same record-and-replay model that
the compositor-process path will use, but keep playback local for now.
Draw calls append CanvasCommandList entries and flush/readback paths
replay the commands into a local CanvasCommandPlayer-owned surface.
This avoids us having to define extra wrappers.
The exceptions to this are `mutable_path` and `my_realm` which are
defined in classes which don't inherit from `AbstractCanvasMixin` and
thus still require a wrapper.
Previously we were inconsistent by generating code for enum definitions
but not generating code for dictionaries. With future changes to the
IDL generator to expose helpers to convert to and from IDL values
this produced circular depdendencies. To solve this problem, also
generate the dictionary definitions in bindings headers.
Previously, the LibWeb bindings generator would output multiple per
interface files like Prototype/Constructor/Namespace/GlobalMixin
depending on the contents of that IDL file.
This complicates the build system as it means that it does not know
what files will be generated without knowledge of the contents of that
IDL file.
Instead, for each IDL file only generate a single Bindings/<IDLFile>.h
and Bindings/<IDLFile>.cpp.
This introduces two new top-level `ValueParsingContext`s,
`OnScreenCanvasContextFontValue` and `CanvasContextGenericValue`, while
these are handled the same for now, there is a distinction is whether or
not they allow tree counting functions (which will come in a later
commit)
Using a generic context argument will allow us to resolve colors in
places where we have all the required information but not in the form of
a layout node as was expected previously.
`CSSColorValue`s which have unresolved `calc` components should be able
to be resolved. Previously we would always resolve them but with
incorrect values.
This is useful as we will now be able to now whether we should serialize
colors in their normalized form or not.
Slight regression in that we now serialize (RGB, HSL and HWB) colors
with components that rely on compute-time information as an empty
string, but that will be fixed in the next commit.
This implements the basic interface, classes and functions for
OffscreenCanvas. Many are still stubbed out and have many FIXMEs in
them, but it is a basic skeleton.
