The tricky bit of this is resolving cycles in extending rules and
ensuring that counter styles are registered in the required order for
extension (i.e. for any pair of extended/extending rules the extended
one should be registered first).
This serves as an intermediate step between `CSSCounterStyleRule` and a
fully built counter style which will be helpful for:
- Determining whether a rule defines a counter style
- Resolving extends cycles
- Determining registration order
Instead of passing through window's associated document's URL as
an extra argument to starting up a worker. This will allow for
improving the representation of 'outside settings' when setting
up a Worker.
This exposes an existing issue with interpolation where it is not clear
in what situations zero-valued dimensions should be excluded from the
interpolated value of a dimension-percentage mix (e.g. `calc(50% + 0px)`
vs `50%`) - but this is just a serialization issue as both
representations are resolved to the same used value
The height and depth attributes are parsed individually and then
combined into a `calc()` expression. Bare zero is valid as a standalone
CSS length but inside `calc()` it is typed as a number, so
`calc(0 + 0)` fails to parse as a length. We now check the parsed value
is valid to avoid a crash.
PlaybackManager's ref counting was only used to keep it alive in a few
callbacks. Instead, the callbacks can use weak references that can only
be used from the thread that the PlaybackManager was created on, to
ensure that the PlaybackManager can't be destroyed while being
accessed.
This ensures that:
- The PlaybackManager is destroyed immediately when it is reassigned
by HTMLMediaElement
- No callbacks are invoked after that point
This fixes the crash initially being addressed by #8081. The test from
that PR has been included as a regression test.
Instead of using a custom paintable to draw the controls for video and
audio elements, we build them out of plain old HTML elements within a
shadow root.
This required a few hacks in the previous commits in order to allow a
replaced element to host children within a shadow root, but it's
fairly self-contained.
A big benefit is that we can drive all the UI updates off of plain old
DOM events (except the play button overlay on videos, which uses the
video element representation), so we can test our media and input event
handling more thoroughly. :^)
The control bar visibility is now more similar to how other browsers
handle it. It will show upon hovering over the element, but if the
cursor is kept still for more than a second, it will hide again. While
dragging, the controls remain visible, and will then hide after the
mouse button is released.
The icons have been redesigned from scratch, and the mute icon now
visualizes the volume level along with indicating the mute state.
We add a new formatting context that simply runs layout for an
anonymous block formatting context within it. This allows replaced
elements to contain children, if the parent rewrites inline-flow to
inline-block.
This is part of the rendering spec, but we had neglected to do this
before. It causes one WPT check to fail, but other browsers get the
same result on that check, so I guess we can call that a win. :^)
These are the same code, so we may as well move them up the chain. This
becomes useful in a later commit, where it will be used to rewrite
inline-flow to inline-block for layout of shadow DOM.
Each NodeWithStyle is assigned a sequential layout index during the
pre-layout tree traversal. LayoutState stores UsedValues in a
PagedStore — a two-level page table indexed by layout_index that
gives O(1) lookup via two array accesses, with pages allocated
lazily on first write. UsedValues are stored directly in pages
(Optional<T>) rather than behind heap pointers, eliminating
per-entry malloc/free calls and improving cache locality.
This cuts ensure_used_values_for() from ~14% to ~7% in profiles
on https://www.nyan.cat/.
The CSS content property's alt text (after `/`) was incorrectly
accepting any content value. Per the CSS Content Module Level 3 spec,
alt text only accepts <string>, <counter>, and <attr()> values. This
change adds type validation in the alt text parsing branch to reject
URLs, quote keywords, images, and other non-alt-text value types.
This fixes 64 subtests in the content-invalid WPT test.
The chain is already in element→root order, which matches the linked
list's natural traversal via parent pointers. No need to collect into
a Vector first.
width_style_value_from_attribute() and
height_style_value_from_attribute() were showing up as hot functions
when profiling YouTube Music. They call parse_css_value() on every
invocation, but the underlying attributes rarely change. The call path
is SVGSVGBox::natural_size() → negotiate_natural_metrics() → these
functions, so they are invoked on every layout pass.
The CSS Overflow spec says scrollable overflow should include "the
scrollable overflow areas of all of the above boxes (including
zero-area boxes)", but we were skipping zero-area boxes entirely via
an early return. This meant elements like a position:relative container
that collapses to zero height (because its only child is absolutely
positioned) would never have their children's overflow counted.
Use the existing bitmap() method which caches the ImmutableBitmap,
instead of creating a fresh snapshot from the painting surface on
every paint call.
This was regressed by d9e04ec9e8 which replaced draw_painting_surface
with a per-call snapshot to remove the DrawPaintingSurface dependency,
but didn't use the existing bitmap cache.
The cursor blink timer fires every 500ms and only needs to toggle
the blink state and mark the paintable as needing display. If the
paintable doesn't exist yet, we can simply skip the blink -- the
cursor will appear after the next natural rendering update.
This avoids a potentially expensive synchronous layout every 500ms
for what is a purely cosmetic operation.
These properties only return the computed border width, which is a
style-level value that doesn't depend on layout geometry. Replace
the full update_layout() call with update_style_if_needed_for_element()
and resolve border widths directly from computed properties.
This avoids potentially expensive synchronous layout when only
CSS computed values are needed.
Very profitable on https://x.com/ where we avoid lots of layout work.
