Previously animation ownership was a messy split between
`AnimatedBitmapDecodedImageData` and the consumers (i.e.
`ImageStyleValueResource`, `HTMLImageElement`, and `SVGImageElement`)
with `AnimatedBitmapDecodedImageData` owning the frames and a current
frame index, and the consumers owning the rest of the state (e.g. loop
count, timers to drive the animation forward, their own current index).
This had a couple of main issues:
- While `AnimatedDecodedImageData` partially synchronized animations by
dropping unexpected advancement notifications, this didn't apply to
other animation state which meant, for instance, that a later started
consumer could drive the animation of an earlier one past the max
loop count (albeit without invalidating the earlier consumer).
- Multiple consumers didn't share frame timings, meaning animations
could be up to a full frame out of sync visually.
- Animations were paused depending on whether there were any consumers,
this is different to the behavior in other browsers (where they
continue regardless of whether there are any consumers).
- It was an overgeneralization of how animations need to work - only
`AnimatedBitmapDecodedImageData` works with an indexed frame model,
with animated SVGs (although not yet implemented) relying on their
internal event loop to be driven forward.
Given the above the new approach implemented in this commit is:
- The API for `DecodedImageData` is animation system agnostic, only
exposing `default_frame`, `current_frame`, and `restart_animation`
methods not reliant on providing a specific frame index.
- `AnimatedBitmapDecodedImageData` owns its own timer, loop count,
etc. The animation starts when the first consumer registers and ends
when the document is hidden or becomes inactive (or completes in the
case of finite animations).
- Consumers are invalidated by `AnimatedBitmapDecodedImageData` when
required.
Tests have been added for:
- Animations being paused when the document becomes inactive and
restarted when it becomes active again.
- Frame timings being synchronized across consumers.
- Restarts triggered by `HTMLImageElement` applying to all consumers.
- Processing ending once a non-infinite animation plays to completion.
The tests to ensure animations are cancelled when consumers are removed
(e.g. `animated-background-image-timer-stops-when-hidden.html`) have
been updated to assert the inverse since animation state is now per
resource not per consumer.
In a future commit, ownership of animation will be transferred from
these clients to `AnimatedDecodedImageData` and we will need a way to
invalidate them for new frames.
This also revealed some `ImageProvider`s which don't yet support
animated images (e.g. `<input type="file">`, `<object>`, etc) but that
is left as a FIXME for now.
`ImageStyleValueResource` now holds a reference to a
`HTML::SharedResourceRequest` for it's entire lifetime.
We also `VERIFY` that we have created a resource (by registering a
client) before calling `ImageStyleValue::image_data` rather than
silently failing.
Previously image animations driven by `ImageStyleValueResource`
invalidated clients using `on_animate`, this was only implemented by the
`background` presentational attribute of `HTMLBodyElement`.
It now uses `notify_clients_did_update` which is implemented by all
clients.
Move the SharedResourceRequest, animation timer, and current frame
state out of ImageStyleValue and into a Document-owned table keyed
by resolved image URL. ImageStyleValue now keeps only URL metadata
and its client list, so image style values no longer need to trace
GC edges themselves.
Thread the Document through AbstractImageStyleValue APIs that need
decoded image data. CSS image fetches snapshot the stylesheet base URL,
referrer behavior, and origin-clean state instead of retaining the
stylesheet.
Remember each client's registered resolved URL when unregistering. This
keeps a later document base change from leaving an animated image
resource alive.
Add text coverage for inline relative image base URLs, stylesheet
referrers, imported stylesheet origin-clean behavior, inline @import
initiator type, and unregistering an animated background image after a
base element change.
ImageStyleValue stored GC-managed request, stylesheet, and animation
timer references as strong GC::Ptr fields even though image style values
are refcounted objects. When such a style value outlives the GC object
that normally visits it, those fields can keep stale pointers after GC
collects the referents. On Steam this allowed a stale image resource
request to be read as unrelated image data, making carousel SVG arrows
render at the wrong size.
Store these back references as GC::Weak instead. Reachable style values
still use live requests, stylesheets, and timers normally, but detached
values observe null after the GC collects the referent and can reload or
skip the now-dead association instead of dereferencing reused GC memory.
Keep a local timer handle while installing the timeout callback so setup
does not rely on the weak member.
With the image style values no longer hiding strong GC edges, remove the
obsolete IGNORE_GC annotation from CSSStyleSheet's pending image list.
Keep animated ImageStyleValue frame advancement owned by the
style value. The current frame and loop state live there, so a
separate document scheduler would duplicate ownership of that state.
Start the ImageStyleValue timer only while it has layout clients.
Stop it when the last client unregisters, or when a finite animation
completes. Expose a document-scoped active timer count through
internals for focused regression tests.
Clear image observers when layout nodes detach. Use current-node
cleanup for per-DOM-node clearing, and explicit subtree cleanup for
tree replacement, full tree teardown, and synthetic pseudo-elements.
This keeps large document clearing linear.
Unregister generated-content image providers during layout detach
instead of waiting for GC to finalize the provider.
Cover hidden animated background images, generated content images,
layout node replacement, full layout tree teardown, and document
scoping for the internals counter.
DecodedImageFrame only wraps a ref-counted Bitmap and color-space
metadata. The frame object itself does not provide shared mutable
state or lifetime ownership beyond those members, so ref-counting it
adds an unnecessary layer of indirection.
DecodedImageFrame now owns decoded bitmap pixels directly, so the
separate ImmutableBitmap wrapper no longer carries useful semantics.
Remove the class and pass decoded image frames or bitmaps at the
boundaries where pixels are actually required.
The Skia image cache now keys off DecodedImageFrame, matching the
display-list commands that paint decoded images. Video frames stay
owned by LibMedia, with the explicit YUV-to-bitmap conversion living
at HTMLVideoElement's decoded-frame entry point for canvas and WebGL
callers.
Decoded image data should not continue to traffic in ImmutableBitmap now
that the bitmap wrapper is being retired. Introduce DecodedImageFrame as
the paintable decoded-image unit and store a Bitmap plus ColorSpace in
it directly.
Thread the new frame type through decoded image data, display-list
image commands, filters, canvas drawImage, patterns, WebGL texture
upload, and CSS/SVG image consumers. ImmutableBitmap remains only at
the legacy boundaries that still need it, such as HTML video snapshots
and callers that explicitly ask for a bitmap snapshot.
This keeps color-space ownership with the decoded frame while making
the expensive or legacy ImmutableBitmap path explicit at the few call
sites that still need it.
Previously, some StyleValues created a large number of intermediate
strings during serialization. Passing a StringBUilder into the
serialization function allows us to avoid a large number of these
unnecessary allocations.
Since we now have access to the `AbstractElement` through the
`ComputationContext` we can just set the flag that this element relies
on tree counting functions directly, no need to pass this struct around.
This struct will in the future hold information other than a length
resolution context (e.g. context for tree counting functions) and a
single struct is easier to work with than multiple parameters.
This reverts 0e3487b9ab.
Back when I made that change, I thought we could make our StyleValue
classes match the typed-om definitions directly. However, they have
different requirements. Typed-om types need to be mutable and GCed,
whereas StyleValues are immutable and ideally wouldn't require a JS VM.
While I was already making such a cataclysmic change, I've moved it into
the StyleValues directory, because it *not* being there has bothered me
for a long time. 😅
PaintContext dates back to a time when display lists didn't exist and it
truly represented "paint context". Renaming it to better align with its
current role.
This patch expands our generated content support beyond single strings
to lists of strings and/or images.
Pseudo-elements like ::before and ::after can now use content:url(...)
to insert anonymous image boxes into the layout tree.
This is heavily used in Google Docs for UI elements.
For getComputedStyle(), we must return an absolute URL for image style
values. We currently return the raw parsed URL.
This fixes loading the marker icons on https://usermap.serenityos.org.
We now don't absolutize the URL during parsing, keeping it as a CSS::URL
object which we then pass to the "fetch an external image for a
stylesheet" algorithm. Our version of this algorithm is a bit ad-hoc,
in order to make use of SharedResourceRequest. To try and reduce
duplication, I've pulled all of fetch_a_style_resource() into a static
function, apart from the "actually do the fetch" step.
To prepare for introducing a CSS::URL type, we need to qualify any use
of LibURL as `::URL::foo` instead of `URL::foo` so the compiler doesn't
get confused.
Many of these uses will be replaced, but I don't want to mix this in
with what will likely already be a large change.
Having this hidden away in ImageStyleValue meant that
CSSStyleProperties (and anyone else who holds style values) had to know
exactly which types need visiting. This is a footgun waiting to happen,
so make this a virtual method on CSSStyleValue instead.
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
