While Origin is defined in the HTML spec - this leaves us with quite an
awkward relationship as the URL spec makes use of AO's from what is
defined in the HTML spec.
To simplify this factoring, relocate Origin into LibURL.
Implements https://github.com/whatwg/html/pull/10007 which basically
moves style, layout and painting from HTML processing task into HTML
task with "rendering" source.
The biggest difference is that now we no longer schedule HTML event loop
processing whenever we might need a repaint, but instead queue a global
rendering task 60 times per second that will check if any documents
need a style/layout/paint update.
That is a great simplification of our repaint scheduling model. Before
we had:
- Optional timer that schedules animation updates 60 hz
- Optional timer that schedules rAF updates
- PaintWhenReady state to schedule a paint if navigable doesn't have a
rendering opportunity on the last event loop iteration
Now all that is gone and replaced with a single timer that drives
repainting at 60 hz and we don't have to worry about excessive repaints.
In the future, hard-coded 60 hz refresh interval could be replaced with
CADisplayLink on macOS and similar API on linux to drive repainting in
synchronization with display's refresh rate.
update_layout() need to be invoked before checking if layout node is
present, because layout not being updated might be the reason why layout
node doesn't exist yet.
Previously, we set the "needs style update" flag to false at the
beginning of recomputing the style. This meant that if any code within
the cascade set this flag to true, then we would end style computation
thinking the element still needed its style updating. This could occur
when starting a transition, and would make TreeBuilder crash.
By ensuring that we always set the flag to false at the very end of
style computation, this is avoided, along with any similar issues - I
noticed a comment in `Animation::cancel()` which sounds like a
workaround was needed for a similar problem previously.
We now use the "report an exception" AO when a script has an execution
error. This has mostly replaced the older "report the exception" AO in
various specifications. Using this newer AO ensures that
`window.onerror` is invoked when a script has an execution error.
When an element is invalidated, it's possible for any subsequent sibling
or any of their descendants to also need invalidation. (Due to the CSS
sibling combinators, `+` and `~`)
For DOM node insertion/removal, we must also invalidate preceding
siblings, since they could be affected by :first-child, :last-child or
:nth-child() selectors.
This increases the amount of invalidation we do, but it's more correct.
In the future, we will implement optimizations that drastically reduce
the number of elements invalidated.
The expensive part of creating a segmenter is doing the locale and UCD
data lookups at creation time. Instead of doing this once per text node,
cache the segmenters on the document, and clone them as needed (cloning
is much, much cheaper).
On a profile loading Ladybird's GitHub repo, the following hot methods
changed as follows:
ChunkIterator ctor: 6.08% -> 0.21%
Segmenter factory: 5.86% -> 0%
Segmenter clone: N/A -> 0.09%
Instead of trying to locate the relevant StyleSheetList on style element
removal from the DOM, we now simply keep a pointer to the list instead.
This fixes an issue where using attachShadow() on an element that had
a declarative shadow DOM would cause any style elements present to use
the wrong StyleSheetList when removing themselves from the tree.
This patch implements `Range::getClientRects` and
`Range::getBoundingClientRect`. Since the rects returned by invoking
getClientRects can be accessed without adding them to the Selection,
`ViewportPaintable::recompute_selection_states` has been updated to
accept a Range as a parameter, rather than acquiring it through the
Document's Selection.
With this change, the following tests now pass:
- wpt[css/cssom-view/range-bounding-client-rect-with-nested-text.html]
- wpt[css/cssom-view/DOMRectList.html]
Note: The test
"css/cssom-view/range-bounding-client-rect-with-display-contents.html"
still fails due to an issue with Element::getClientRects, which will
be addressed in a future commit.
DOM nodes that didn't have a layout node before being removed from the
DOM are not going to change the shape of the layout tree after being
removed.
Observing this, we can avoid a full layout tree rebuild on some DOM node
removals.
This avoids a bunch of tree building work when loading https://x.com/
Computing the "contained text auto directionality" is now its own
algorithm, with an extra parameter, and is additionally called from
step 2.1.3.2 instead of calling "auto directionality".
Before this change, a formatting context was responsible for layout of
absolutely positioned boxes whose FC root box was their parent (either
directly or indirectly). This only worked correctly when the containing
block of the absolutely positioned child did not escape the FC root.
This is because the width and height of an absolutely positioned box are
resolved based on the size of its containing block, so we needed to
ensure that the containing block's layout was completed before laying
out an absolutely positioned box.
With this change, the layout of absolutely positioned boxes is delayed
until the FC responsible for the containing block's layout is complete.
This has affected the way we calculate the static position. It is no
longer possible to ask the FC for a box's static position, as this FC's
state might be gone by the time the layout for absolutely positioned
elements occurs. Instead, the "static position rectangle" (a concept
from the spec) is saved in the layout state, along with information on
how to align the box within this rectangle when its width and height are
resolved.
FormattingContext::run() does not allow reentrancy, so it's safe to
save and access layout mode from FC object. This avoids need to drill it
through methods of a formatting context and makes it clear that this
value could never be changed after FC construction.
Root formatting context box is passed into constructor and saved in FC,
so it's possible to access it from there instead of passing the same
box into run().
Previously, there was a bug in the specification that would cause an
assertion failure, due to the abort event being fired before all
dependent signals were aborted.
When setting an element attribute to the value it already had, we don't
need to update style or invalidate anything that depends on the DOM
version counter.
This was a source of much pointless busywork.
You can now build with STYLE_INVALIDATION_DEBUG and get a debug stream
of reasons why style invalidations are happening and where.
I've rewritten this code many times, so instead of throwing it away once
again, I figured we should at least have it behind a flag.
When accessed on the root/document element, the following properties are
derived from the viewport, not layout-dependent metrics:
- scrollLeft
- scrollTop
- scrollWidth
- scrollHeight
We now avoid synchronous layout in such cases. This was causing some
unnecessary layout work when loading https://vercel.com/
This API is a relic from the time when it was important for objects to
have easy access to the Window, and to know it was the global object.
We now have more spec-related concepts like relevant_global_object and
current_global_object to pull the Window out of thin air.
This will be used by the inspector, for showing style sheet contents.
Identifying a specific style sheet is a bit tricky. Depending on where
it came from, a style sheet may have a URL, it might be associated with
a DOM element, both, or neither. This varied information is wrapped in
a new StyleSheetIdentifier struct.
Calls to `Document::set_needs_display()` and
`Paintable::set_needs_display()` now invalidate the display list by
default. This behavior can be changed by passing
`InvalidateDisplayList::No` to the function where invalidating the
display list is not necessary.
Use offset from ScrollFrame which is an actual value a box is shifted by
while painting.
Also change `update_paint_and_hit_testing_properties_if_needed()` to
refresh scroll frames state, because `getBoundingClientRect()` now
depends on them.
Fixes wrong file tree sidebar location and excessive layout
invalidations caused by some miscalculation on JS-side when wrong
bounding client rect is provided on Github PR pages like
https://github.com/LadybirdBrowser/ladybird/pull/1232/files
Sticky positioning is implemented by modifying the algorithm for
assigning and refreshing scroll frames. Now, elements with
"position: sticky" are assigned their own scroll frame, and their
position is refreshed independently from regular scroll boxes.
Refreshing the scroll offsets for sticky boxes does not require display
list invalidation.
A separate hash map is used for the scroll frames of sticky boxes. This
is necessary because a single paintable box can have two scroll frames
if it 1) has "position: sticky" and 2) contains scrollable overflow.
