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.
DOM nodes now have two additional flags:
- Needs layout tree update
- Child needs layout tree update
These work similarly to the needs-style-update flags, but instead signal
the need to rebuild the corresponding part of the layout tree.
When a specific DOM node needs a layout tree update, we try to create
a new subtree starting at that node, and then replace the subtree in the
old layout tree with the newly created subtree.
This required some refactoring in TreeBuilder so that we can skip over
entire subtrees during a tree update.
Note that no partial updates happen yet (as of this commit) since we
always invalidate the full layout tree still. That will change in the
next commit.
Per https://w3c.github.io/aria/#document-handling_author-errors_roles,
determining whether to ignore certain specified landmark roles requires
first determining whether the element for which the role is specified
has an accessible name.
But if we then try to retrieve a role for such elements, we end up
calling right back into the accessible-name computation code — which
would cause the calls to loop infinitely.
So to avoid that — and to have handling for any other future cases the
spec may introduce of such recursive calls that will loop indefinitely —
this change introduces a parameter that callers can pass to cause
role-attribute lookup to be skipped during accessible-name computation.
When setting the textContent of an element with no children to null or
the empty string, nothing happens. Even so, we were still invalidating
style, layout and collections, causing pointless churn.
Skipping invalidation in this case also revealed that we were missing
invalidation when changing the selected state of HTMLOptionElement.
This was all caught by existing tests already in-tree. :^)
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.
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.
The DOM spec defines what it means for an element to be an "editing
host", and the Editing spec does the same for the "editable" concept.
Replace our `Node::is_editable()` implementation with these
spec-compliant algorithms.
An editing host is an element that has the properties to make its
contents effectively editable. Editable elements are descendants of an
editing host. Concepts like the inheritable contenteditable attribute
are propagated through the editable algorithm.
CDATASection inherits from Text, and so it was incorrect for them to
claim not to be Text nodes.
This fixes at least two WPT subtests. :^)
It also exposed a bug in the DOM Parsing and Serialization spec,
where we're not told how to serialize CDATASection nodes.
Spec bug: https://github.com/w3c/DOM-Parsing/issues/38
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
This change removes the append_without_space, append_with_space,
prepend_without_space, and prepend_with_space functions from DOM::Node.
All those methods were added with the initial “Implement Accessible Name
and Description Calculation” commit in da5c918 and were only used in the
code related to accessible-name computation. But subsequent changes to
that code have removed all the calls to those functions — so now they’re
all completely unused.
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.
Now that we have RTTI in userspace, we can do away with all this manual
hackery and use dynamic_cast.
We keep the is<T> and downcast<T> helpers since they still provide good
readability improvements. Note that unlike dynamic_cast<T>, downcast<T>
does not fail in a recoverable way, but will assert if the object being
casted is not a T.
Now that documents are attached to their frame *before* parsing, we can
create the content frame of <iframe> elements right away, instead of
waiting for the host frame attachment.
Fixes#4408.
This patch adds a second style dirty bit that tracks whether a DOM node
has one or more children with dirty style. This allows the style update
to skip over entire subtrees where all nodes are clean.
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.
Specification: https://dom.spec.whatwg.org/#concept-event-dispatch
This also introduces shadow roots due to it being a requirement of
the event dispatcher.
However, it does not introduce the full shadow DOM, that can be
left for future work.
This changes some event dispatches which require certain attributes
to be initialised to a value.
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!)
DOM::Node now points to its LayoutNode with a WeakPtr.
LayoutNode points to its DOM::Node and DOM::Document with RefPtrs.
Layout trees come and go in response to various events, so the DOM tree
already has to deal with that. The DOM should always live at least as
long as the layout tree, so this patch enforces that assumption by
making layout nodes keep their corresponding DOM objects alive.
This may not be optimal, but it removes a lot of ambiguous raw pointer
action which is not worth accomodating.
In addition to being reference-counted, all nodes that are part of a
document must also keep the document alive.
This is achieved by adding a second ref-count to the Document object
and incrementing/decrementing it whenever a node is created/destroyed
in that document.
This brings us much closer to a proper DOM lifetime model, although
the JS bindings still need more work.
For now, the new DOM::EventDispatcher is very simple, it just iterates
over the set of listeners on an EventTarget and invokes the callbacks
as it goes.
This simplifies EventTarget subclasses since they no longer have to
implement the callback mechanism themselves.
This requires moving remove_all_children() from ParentNode to
Node, which makes ParentNode.cpp empty, so remove it.
It also co-opts the existing Node::text_content() method and
tweaks it slightly to fit the semantics of Node.textContent.
This is mostly to get the grunt work of the way. This is split up into
multiple commits to hopefully make it more manageable to review.
Note that these are not full implementations, and the bindings mostly
get the low hanging fruit.
Also implements some attributes that I kept out because they had
dashes in them. Therefore, this closes#2905.
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.
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 is a very barebones implementation of appendChild() that doesn't
take any of the idiosyncratic DOM behaviors into account yet.
Also teach the wrapper generator how to turn an Interpreter argument
into a Node&.
The more generic virtual variant is renamed to node_name() and now only
Element has tag_name(). This removes a huge amount of String ctor/dtor
churn in selector matching.
