We previously had PropertyOwningCSSStyleDeclaration and
ResolvedCSSStyleDeclaration, representing the current style properties
and resolved style respectively. Both of these were the
CSSStyleDeclaration type in the CSSOM. (We also had
ElementInlineCSSStyleDeclaration but I removed that in a previous
commit.)
In the meantime, the spec has changed so that these should now be a new
CSSStyleProperties type in the CSSOM. Also, we need to subclass
CSSStyleDeclaration for things like CSSFontFaceRule's list of
descriptors, which means it wouldn't hold style properties.
So, this commit does the fairly messy work of combining these two types
into a new CSSStyleProperties class. A lot of what previously was done
as separate methods in the two classes, now follows the spec steps of
"if the readonly flag is set, do X" instead, which is hopefully easier
to follow too.
There is still some functionality in CSSStyleDeclaration that belongs in
CSSStyleProperties, but I'll do that next. To avoid a huge diff for
"CSSStyleDeclaration-all-supported-properties-and-default-values.txt"
both here and in the following commit, we don't apply the (currently
empty) CSSStyleProperties prototype yet.
Previously, parse_css_style_attribute() would parse the string, extract
the properties, add them to a newly-created
ElementInlineCSSStyleDeclarations, and then user code would take the
properties back out of it again and throw it away. Instead, just return
the list of properties, and the caller can create an EICSD if it needs
one.
Element styles should be invalidated when they depend on CSS variables
defined in one of their ancesors or when one of their ancestors change
their class, due to the possibility of adding new CSS variables in
scope.
If an element is affected only by selectors using the direct sibling
combinator `+`, we can calculate the maximum invalidation distance and
use it to limit style invalidation. For example, the selector
`.a + .b + .c` has a maximum invalidation distance of 2, meaning we can
skip invalidating any element affected by this selector if it's more
than two siblings away from the element that triggered the style
invalidation.
This change results in visible performance improvement when hovering
PR list on GitHub.
A font-size with rem units need to resolve against the default font
metrics for the root element, otherwise every time we compute style,
the reference value for rem units grows.
This fixes an issue where text on some web pages would grow every time
there was a relayout. This was very noticeable on https://proton.me/Fixes#339
We already have logic to play or cancel animations in an element's
subtree when the display property changes to or from none. However,
this was not sufficient to cover the case when an element starts/stops
being nested in display none after insertion.
The DOMParsing spec is in the process of being merged into the HTML one,
gradually. The linked spec change moves XMLSerializer, but many of the
algorithms are still in the DOMParsing spec so I've left the links to
those alone.
I've done my best to update the GN build but since I'm not actually
using it, I might have done that wrong.
Corresponds to 2edb8cc7ee
...in inherited style update. Instead of comparing old absolutized value
with new non-absolutized value, we should wait until
`absolutize_values()` and then compare old and new values, when both are
absolutized.
Improves performance on pages with GitHub action logs where previously
we had to invalidate layout after hover style recalculation, because
there was `margin-left: 1rem`.
Instead of checking all elements in a document for containment in
`:has()` invalidation set, we could narrow this down to ancestors and
ancestor siblings, like we already do for subject `:has()` invalidation.
This change brings great improvement on GitHub that has selectors with
non-subject `:has()` and sibling combinators (e.g., `.a:has(.b) ~ .c`)
which prior to this change meant style invalidation for whole document.
This allows us to inspect its properties. To avoid wasted work, we only
compute and cache the properties if the originating element was, or is,
displaying as a list item.
Moves pseudo class matching helpers into Element methods, so they don't
have to be duplicated between SelectorEngine and function that checks if
element is included in invalidation set.
With this change, siblings of an inserted node are no longer invalidated
unless the insertion could potentially affect their style. By
"potentially affected," we mean elements that are evaluated against the
following selectors during matching:
- Sibling combinators (+ or ~)
- Pseudo-classes :first-child and :last-child
- Pseudo-classes :nth-child, :nth-last-child, :nth-of-type, and
:nth-last-of-type
This is not really a context, but more of a set of parameters for
creating a Parser. So, treat it as such: Rename it to ParsingParams,
and store its values and methods directly in the Parser instead of
keeping the ParsingContext around.
This has a nice side-effect of not including DOM/Document.h everywhere
that needs a Parser.
While keyword_to_foo() does return Optional<Foo>, in practice the
invalid keywords get rejected at parse-time, so we don't have to worry
about them here. This simplifies the user code quite a bit.
Currently, this metadata is only provided on the insertion steps,
though I believe it would be useful to extend to the other cases
as well. This metadata can aid in making optimizations for these
steps by providing extra context into the type of change which
was made on the child.
Prior to this change, we invalidated all elements in the document if it
used any selectors with :has(). This change aims to improve that by
applying a combination of techniques:
- Collect metadata for each element if it was matched against a selector
with :has() in the subject position. This is needed to invalidate all
elements that could be affected by selectors like `div:has(.a:empty)`
because they are not covered by the invalidation sets.
- Use invalidation sets to invalidate elements that are affected by
selectors with :has() in a non-subject position.
Selectors like `.a:has(.b) + .c` still cause whole-document invalidation
because invalidation sets cover only descendants, not siblings. As a
result, there is no performance improvement on github.com due to this
limitation. However, youtube.com and discord.com benefit from this
change.
...by replacing existing method to check if an element is affected by
invalidation property. It turned out there is no need to check if an
element is affected only by some specific property, so it's more
convenient to have a method that accepts the whole set.
We have an optimization that allows us to invalidate only the style of
the element itself and mark descendants for inherited properties update
when the "style" attribute changes (unless there are any CSS rules that
use the "style" attribute, then we also invalidate all descendants that
might be affected by those rules). This optimization was not taking into
account that when the inline style has custom properties, we also need
to invalidate all descendants whose style might be affected by them.
This change fixes this bug by saving a flag in Element that indicates
whether its style depends on any custom properties and then invalidating
all descendants with this flag set when the "style" attribute changes.
Unlike font relative lengths invalidation, for elements that depend on
custom properties, we need to actually recompute the style, instead of
individual properties, because values without expanded custom properties
are gone after cascading, and it has to be done again.
The test added for this change is a version of an existing test we had
restructured such that it doesn't trigger aggressive style invalidation
caused by DOM structured changes until the last moment when test results
are printed.
Instead, change the APIs from "has :foo" to "may have :foo" and return
true if we don't have a valid rule cache at the moment.
This allows us to defer the rebuilding of the rule cache until a later
time, for the cost of a wider invalidation at the moment.
Do note that if our rule cache is invalid, the whole document has
invalid style anyway! So this is actually always less work. :^)
Knocks ~1 second of loading time off of https://wpt.fyi/
The existing `::unite_horizontally()` and `::unite_vertically()` tests
did not properly test the edge cases where left/top in the Rect were
updated, so they get re-arranged a bit.
Use invalidation sets for presentational hint attribute invalidation
instead of falling back to full descendants and siblings invalidation.
The only difference for presentational hint attributes is that we always
have to invalidate the style of element itself.
Implements idea described in
https://docs.google.com/document/d/1vEW86DaeVs4uQzNFI5R-_xS9TcS1Cs_EUsHRSgCHGu8
Invalidation sets are used to reduce the number of elements marked for
style recalculation by collecting metadata from style rules about the
dependencies between properties that could affect an element’s style.
Currently, this optimization is only applied to style invalidation
triggered by class list mutations on an element.
These common cases now cause us to invalidate the layout tree starting
at the relevant parent node instead of invalidating the entire tree.
- DOM node insertion
- DOM node removal
- innerHTML setter
- textContent setter
This makes a lot of dynamic content much faster. For example, demos
on shadertoy.com go from ~18 fps to ~28 fps on my machine.
This makes it more convenient to use the 'relvant agent' concept,
instead of the awkward dynamic casts we needed to do for every call
site.
mutation_observers is also changed to hold a GC::Root instead of raw
GC::Ptr. Somehow this was not causing problems before, but trips up CI
after these changes.
Instead of recalculating styles for all nodes in the common ancestor of
the new and old hovered nodes' subtrees, this change introduces the
following approach:
- While calculating ComputedProperties, a flag is saved if any rule
applied to an element is affected by the hover state during the
execution of SelectorEngine::matches().
- When the hovered element changes, styles are marked for recalculation
only if the flag saved in ComputedProperties indicates that the
element could be affected by the hover state.
The "strictly split" infra algorithm feels like an inefficient way of
doing basically what our existing split() does, except working with
code points instead of bytes. It didn't seem worth it to implement now.
1. Stop using GC::Root in member variables, since that usually creates
a realm leak.
2. Stop putting OrderedHashMap<FlyString, GC::Ptr> on the stack while
setting these up, since that won't protect the objects from GC.
If there are no :defined pseudo-class selectors anywhere in the
document, we don't have to invalidate style at all when an element's
custom element state changes.
Many times, attribute mutation doesn't necessitate a full style
invalidation on the element. However, the conditions are pretty
elaborate, so this first version has a lot of false positives.
We only need to invalidate style when any of these things apply:
1. The change may affect the match state of a selector somewhere.
2. The change may affect presentational hints applied to the element.
For (1) in this first version, we have a fixed list of attribute names
that may affect selectors. We also collect all names referenced by
attribute selectors anywhere in the document.
For (2), we add a new Element::is_presentational_hint() virtual that
tells us whether a given attribute name is a presentational hint.
This drastically reduces style work on many websites. As an example,
https://cnn.com/ is once again browseable.
When the `style` attribute changes, we only need to update style on the
element itself (unless there are [style] attribute selectors somewhere).
Descendants of the element don't need a full style update, a simple
inheritance propagation is enough.
We can now mark an element as needing an "inherited style update" rather
than a full "style update". This effectively means that the next style
update will visit the element and pull all of its inherited properties
from the relevant ancestor element.
This is now used for descendants of elements with animated style.
Before this change, StyleComputer would essentially take a DOM element,
find all the CSS rules that apply to it, and resolve the computed value
for each CSS property for that element.
This worked great, but it meant we had to do all the work of selector
matching and cascading every time.
To enable new optimizations, this change introduces a break in the
middle of this process where we've produced a "CascadedProperties".
This object contains the result of the cascade, before we've begun
turning cascaded values into computed values.
The cascaded properties are now stored with each element, which will
later allow us to do partial updates without re-running the full
StyleComputer machine. This will be particularly valuable for
re-implementing CSS inheritance, which is extremely heavy today.
Note that CSS animations and CSS transitions operate entirely on the
computed values, even though the cascade order would have you believe
they happen earlier. I'm not confident we have the right architecture
for this, but that's a separate issue.
There are some special values for CSS::Selector::PseudoElement::Type
which are after `KnownPseudoElementCount` and therefore not present in
various arrays of pseudo elements, this leads to some errors, if a type
after `KnownPseudoElementCount` is used without checking first. This
adds explicit checks to all usages
This change implements full support for the “A. Hidden Not Referenced”
step at https://w3c.github.io/accname/#step2A in the “Accessible Name
and Description Computation” spec — including handling all hidden nodes
that must be ignored, as well as handling hidden nodes that, for the
purposes of accessible-name computation, must not be ignored (due to
having aria-labelledby/aria-describedby references from other nodes).
Otherwise, without this change, not all cases of hidden nodes get
ignored as expected, while cases of nodes that are hidden but that have
aria-labelledby/aria-describedby references from other nodes get
unexpectedly ignored.
Previously any existing ElementInlineCSSStyleDeclaration would get
overwritten by e.setAttribute("style", ...), while it should be updated
instead.
This fixes 2 WPT subtests.
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
We currently have 2 virtual methods to inform DOM::Element subclasses
when an attribute has changed, one of which is spec-compliant. This
patch removes the non-compliant variant.
Now that the heap has no knowledge about a JavaScript realm and is
purely for managing the memory of the heap, it does not make sense
to name this function to say that it is a non-realm variant.
The main motivation behind this is to remove JS specifics of the Realm
from the implementation of the Heap.
As a side effect of this change, this is a bit nicer to read than the
previous approach, and in my opinion, also makes it a little more clear
that this method is specific to a JavaScript Realm.
Instead of doing a forced layout synchronously whenever an element's
style is changed, use a zero-timer to do the forced relayout on next
event loop iteration.
This effectively coalesces a lot of layouts and makes many pages such
as GitHub spend way less time doing redundant layout work.
The StyleResolver can find the specified CSS values for the parent
element via the DOM. Forcing everyone to locate specified values for
their parent was completely unnecessary.
Layout nodes now only carry CSS computer values with them. The main
idea here is to give them only what they need to perform layout, and
leave the rest back in the DOM.
Otherwise fetching stuff via LayoutNode::style() will have stale values
since we were only updating the specified_style() here.
LayoutNode::specified_style() should eventually go away since there's
no need to carry those uncooked values around with the layout tree.
This patch adds a simple, naive & inefficient class for document-wide
style invalidation, e.g. after element attribute updates. During
construction it collects a HashMap of a document's elements and their
matching rules, during destruction it does the same and then compares
the results; dirtying all elements that have a different number or order
of matching rules afterwards.
Much room for improvement, but it solves the problem of stale element
styling after attribute updates for now :^)
Fixes#4404.
After you mark a node as needing new style, there's no situation in
which we don't want a style update to happen, so just take care of
scheduling it automatically.
Instead of invoking the CSS parser every time we compute the style for
an element that has a "style" attribute, we now cache the result of
parsing the inline style whenever the "style" attribute is set.
This is a nice boost to relayout performance since we no longer hit the
CSS parser at all.
Bring the names of various boxes closer to spec language. This should
hopefully make things easier to understand and hack on. :^)
Some notable changes:
- LayoutNode -> Layout::Node
- LayoutBox -> Layout::Box
- LayoutBlock -> Layout::BlockBox
- LayoutReplaced -> Layout::ReplacedBox
- LayoutDocument -> Layout::InitialContainingBlockBox
- LayoutText -> Layout::TextNode
- LayoutInline -> Layout::InlineNode
Note that this is not strictly a "box tree" as we also hang inline/text
nodes in the same tree, and they don't generate boxes. (Instead, they
contribute line box fragments to their containing block!)
Reading the property has a few warts (see FIXMEs in the included
tests), but with this the timestamps on http://45.33.8.238/
get localized :^)
Since the Date() constructor currently ignores all arguments,
they don't get localized correctly but are all set to the current
time, but hey, it's still progress from a certain point of view.
You can now cycle through focusable elements (currently only hyperlinks
are focusable) with the Tab key.
The focus outline is rendered in a new FocusOutline paint phase.
HTMLElement is the only interface that includes ElementContentEditable
in the HTML specification. This makes sense, as Element is also a base
class for elements in other specifications such as SVG,
which definitely shouldn't be editable.
Also adds a test for the attribute based on what Andreas did in the
video that added it.
LibWeb keeps growing and the Web namespace is filling up fast.
Let's put DOM stuff into Web::DOM, just like we already started doing
with SVG stuff in Web::SVG.
To prepare for fully qualified tag names, let's call this local_name.
Note that we still keep an Element::tag_name() around since that's what
the JS bindings end up calling into for the Element.tagName property.
This patch implements most of the HTML fragment parsing algorithm and
ports Element::set_inner_html() to it. This was the last remaining user
of the old HTML parser. :^)
To make this possible, I also had to give each LayoutNode a Document&
so it can resolve document-specific colors correctly. There's probably
ways to avoid having this extra member by resolving colors later, but
this works for now.
This makes stuff inside <noscript> correctly not show up since we run
with scripting enabled.
In the future, we can add a way to disable scripting, but for now,
Document::is_scripting_enabled() just returns true.
This seems to have a higher chance of generating somewhat recognizable
content compared to inline layout. This problem will gradually go away
as we implement more display values.
Instead of string splitting every time you call Element::has_class(),
we now split the "class" attribute value when it changes, and cache
the individual classes as FlyStrings in Element::m_classes.
This makes has_class() significantly faster and moves the pain point
of selector matching somewhere else.
This display type is implemented using a LayoutBlock that is_inline().
Basically it behaves like a block internally, and its children are laid
out in the normal block layout fashion. Externally however, it behaves
like an atomic inline-level box.
Layout of inline-block boxes happens in three stages:
1. The outer dimensions of the block are computed during the recursive
normal layout pass. We skip positioning, but lay out children.
2. Later on, during line layout in the *containing block*, the inline
block now contributes a linebox fragment. When linebox fragments are
positioned, we learn the final position of the inline block. That's
when we set the inline block's position.
3. We re-layout the inline block's children once again. This is done to
make sure they end up in the right position. The layout tree doesn't
use relative offsets, so after we position the inline block in (2),
its children will not have its positions updated. Relayout moves
all children of inline blocks to the right place.
This is a rather naive approach but it does get the basic behavior into
place so we can iterate on it. :^)
Getting the innerHTML property will recurse through the subtree inside
the element and serialize it into a string as it goes.
Setting it will parse the set value as an HTML fragment. It will then
remove all current children of the element and replace them with all
the children inside the parsed fragment.
Setting element.innerHTML will currently force a complete rebuild of
the document's layout tree.
This is pretty neat! :^)
