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.
We don't have to invalidate style for the entire document when a style
sheet changes inside of a shadow root.
To make this possible, StyleSheetList now keeps track of which
Document-or-ShadowRoot it corresponds to, instead of just tracking the
containing Document.
This avoids a lot of style recomputation on pages with lots of shadow
DOM content (like GitHub).
Before this change, we would go through every known pseudo element and
compute style for it whenever recomputing the style of an element.
This led to disastrous performance on pages with selectors like
`::selection` or `::placeholder`, as they'd effectively match every
single element and thus we'd compute multiple additional styles for
every element in the DOM.
The fix is simple: only recompute `before` and `after` pseudo element
styles, since those are the only two pseudo elements that generate
*new* nodes -- other pseudo elements refer to (possibly) existing
nodes or concepts within the DOM (or internal shadow DOM).
This makes style updates take ~40ms on our GitHub repo instead of
~220ms. It's still slower than it should be, but a huge improvement.
`BrowsingContext::m_parent` has been removed from the spec,
and previously `m_parent` was always null.
`BrowsingContext::is_top_level` was already always returning
true before because of that, and the updated spec algorithm
causes assertions to fail.
This fixes the following example:
```html
<a href="about:blank" target="test">a
<iframe name="test">
```
clicking the link twice no longer causes it to open in a new tab.
...if only the scroll offset is updated.
Currently, on any document with a large amount of content, the process
of building a display list is often more expensive than its
rasterization. This is because the amount of work required to build a
display list is proportional to the size of the paintable tree, whereas
rasterization only occurs for the portion visible in the viewport.
This change is the first step toward improving this process by caching
the display list across repaints when neither style nor layout requires
invalidation. This means that repainting while scrolling becomes
significantly less expensive, as we only need to reapply the scroll
offsets to the existing display list.
The performance improvement is especially visible on pages like
https://ziglang.org/documentation/master/ or
https://www.w3.org/TR/css-grid-2/
For a long time, we've used two terms, inconsistently:
- "Identifier" is a spec term, but refers to a sequence of alphanumeric
characters, which may or may not be a keyword. (Keywords are a
subset of all identifiers.)
- "ValueID" is entirely non-spec, and is directly called a "keyword" in
the CSS specs.
So to avoid confusion as much as possible, let's align with the spec
terminology. I've attempted to change variable names as well, but
obviously we use Keywords in a lot of places in LibWeb and so I may
have missed some.
One exception is that I've not renamed "valid-identifiers" in
Properties.json... I'd like to combine that and the "valid-types" array
together eventually, so there's no benefit to doing an extra rename
now.
While introducing clip and scroll frame trees, I made a mistake by
assuming that the paintable tree includes boxes from nested navigables.
Therefore, this comment in the code was incorrect, and clip/scroll
frames were simply not assigned for iframes:
// NOTE: We only need to refresh the scroll state for traversables
// because they are responsible for tracking the state of all
// nested navigables.
As a result, anything with "overflow: scroll" is currently not
scrollable inside an iframe
This change fixes that by ensuring clip and scroll frames are assigned
and refreshed for each navigable. To achieve this, I had to modify the
display list building process to record a separate display list for each
navigable. This is necessary because scroll frame ids are local to a
navigable, making it impossible to call
`DisplayList::apply_scroll_offsets()` on a display list that contains
ids from multiple navigables.
If a DOM node is an element with pseudo-elements, but it has no child
DOM nodes and is not a shadow host, then the code that serializes its
pseudo-elements would get skipped, making them not show up in the
inspector.
I previously believed there was no way a detached document should have
layout information, but it turns out there is a way: getComputedStyle().
So we need to account for cases where we have a layout node, but no
navigable, since that is a state we can get into at this moment.
Fixes#354
For the SVG <use> element, we want to support loading HTML documents
that have a SVG element inside of it pointed to by the URL fragment.
In this situation we would need to fetch and parse the entire document
in SharedImageRequest (so that we can still cache the SVGs). Rename
SharedImageRequest to SharedResourceRequest to make the class a little
more generic for future usecases.
This also fixes a bug where task IDs were being deallocated from the
wrong IDAllocator. I don't know if it was actually possible to cause any
real trouble with that mistake, nor do I know how to write a test for
it, but this makes the bug go away.
To avoid expensive lookups, we now cache a weak pointer from document to
the last known node navigable. Before using the cache, we validate that
the document is still the navigable's active document.
We were saving to source declarations for *every* property, even though
we only ever looked it up for animation-name.
This patch gets rid of the per-property source pointer and we now keep
a single pointer to the animation-name source only.
This shrinks StyleProperties from 6512 bytes to 4368 bytes per instance.
Navigables are re-used for navigations within the same tab. Its current
ownership of the cursor position is a bit ad-hoc, so nothing in the spec
indicates when to reset the cursor, nor do we manually do so. So when a
cursor update happens on one page, that cursor is retained on the next
page.
Instead, let's have the document own the cursor. Each navigation results
in a new document, thus we don't need to worry about resetting cursors.
This also makes many of the callsites feel nicer. We were previously
often going from the node, to the document, to the navigable, to the
cursor. This patch removes the navigable hop.
We explicitly stopped visting the map of documents to console clients in
commit 44659f2f2a to avoid keeping the
document alive. However, if nothing else visits the console clients, we
may set the top-level console client to a client that has been garbage
collected.
So instead of storing this map, just store the console client on the
document itself. This will allow the document to visit its client.
Previously, pseudo-elements had their style computed while the layout
tree was being built. Instead, do so inside Element::recompute_style(),
using the same invalidation mechanism that the element itself uses.
This also has the effect of invalidating the layout much less often.
Pseudo-elements' style is only computed while building the layout tree.
This meant that previously, they would not have their style recomputed
in some cases. (Such as when :hover is applied to an ancestor.)
Now, when recomputing an element's style, we also return a full
invalidation if one or more pseudo-elements would exist either before or
after style recomputation.
This heuristic produces some false positives, but no false negatives.
Because pseudo-elements' style is computed during layout building, any
computation done here is then thrown away. So this approach minimises
the amount of wasted style computation. Plus it's simple, until we have
data on what approach would be faster.
This fixes the Acid2 nose becoming blue when the .nose div is hovered.
This removes some ambiguity about what the return value should be if
the index is out of range.
Previously, we would sometimes return a JS null, and other times a JS
undefined.
It will also let us fold together the checks for whether an index is a
supported property index, followed by getting the value just afterwards.
These control the state of CSS counters.
Parsing code for `reversed(counter-name)` is implemented, but disabled
for now until we are able to resolve values for those.
This represents each element's set of CSS counters.
https://drafts.csswg.org/css-lists-3/#css-counters-set
Counters are resolved while building the tree. Most elements will not
have any counters to keep track of, so as an optimization, we don't
create a CountersSet object until the element actually needs one.
In order to properly support counters on pseudo-elements, the
CountersSet needs to go somewhere else. However, my experiments with
placing it on the Layout::Node kept hitting a wall. For now, this is
fairly simple at least.
